Sonobuoys & Outdoor Intrusion Detectors

Brooke Clarke 2011 - 2021

    Types of Sonobuoys
    CNU-239/E Shipping Tube 
    Radio Channels
        Black Box Beacon Transmitter
    DIrectional Frequency Analysis & Recording type acoustic sensor (DIFAR)
    Reserve Batteries 
        Reserve Battery Patents     
        Light, Emergency Sea Rescue Marker
Table of Sonobuoys
    Glass Slides
    Dittmore & Freimuth
    SSXBT Model ST-1
    Bathythermograph Patents
Niskin Bottle
SUS: Signal Underwater Sound
Sonobuoy Aircraft Systems
Outdoor Intrusion Detectors based on Sonobuoy Technology
    Link between Vietnam Intrusion Detectors and Navy
    Mines for Noise
    1st Generation
USQ-42 Receiver
R-1617A/USQ-46 Receiver
ID-1721 Indicator WANTED TO BUY
PP-6446A/USQ-46 Power Supply    
    Dr. Breed & Hughes
    Launching Sonobuoy
Magnetic Anomaly Detector (MAD)
    C820 Control Panel
    17H-4 Gamma Slinger
    MAD patents
SONAR Countermeasures
Hazeltine Hydrophone and Retainer Assembly A22267-1
Roswell Connection
Unknown Sonobuoy - What is it?
Unknown Sonobuoy No. 2 (Greece)
Underwater Communications
    BQC-1 Underwater Telephone
    Communication Buoy
Submarine Missile Hanger
Submerged Signal Ejector
P-3C Systems


During the Vietnam era the "electronic battlefield" (book: Military Communications: A Test for Technology) was developed and it included various outdoor intrusion alarms (my name for these devices).  Some, like the PSR-1 Seismic Intrusion Detector, used wire between the sensors and the main unit and others used a radio transmitter in the sensor and the main unit was a radio receiver.

The frequency spectrum has allocations for different users (see Frequency Allocations).  One band is used by aircraft for communication and navigation (108 to 136 MHz).  A number of Vietnam era outdoor intrusion sensors used this band.

Another band is used for sonobuoy operations by the Navy (162.25 to 173.50 MHz with  31 channels with 375 kHz spacing). This page is about these outdoor intrusion sensors.

Department of Defense Training Film MF11-5514
Bugging the Battlefield pt1-2 1969 Defense Department Electronic Eavesdropping Vietnam War
Bugging the Battlefield pt2-2 1969 Defense Department Electronic Eavesdropping Vietnam War
Electronic Eavesdropping, Vietnam War: "Bugging the Battlefield" 1969 Defense Department (30:28) - combined part 1 & 2

Submarines & the Noises they Make

The early work on SOund Navigation And Ranging (Wiki: SONAR), which was named after RAdio Navigation And Ranging (Wiki: RADAR), was done utilizing audio frequencies were an operator would listen on headphones (for those systems that used stereo) or a loudspeaker.  The first sonobuoys also used audio with a human operator listening to the sound.  This is called passive SONAR (code name Jezebel).  There are no pings and whoever is doing the listening is not giving away their presence or position.  When it works it's the preferred method and is by far the most common.  In the 1950s the SOund SUrveillance System (Wiki: SOSUS, my page) which makes use of LOw Frequency Analysis and Recording (LOFAR) rather than the use of human audible sound was put into service.  This worked on snorkeling diesel electric subs (Wiki) and on nuclear powered subs like the Soviet Hotel (Wiki), Echo (Wiki) & November (Wiki) class subs (HEN).

Active SONAR comes in two flavors, the most commonly known is the active ping like in any movie involving submarines.  A ping is sent out and the time measured until it returns.  The early pings were audible to humans, later ultrasonic pings were used and later still the frequency of the ping changed it into a chirp.  If the propagation speed is known the distance to the target can be calculated and with the later types the radial speed of the target can be determined.  The less well known active SONAR method (code name Julie) involves setting off an explosion of a couple of pounds of TNT using either the Mk-15 (Mod-12) or Mk-61 Signal Underwater Sound (SUS).  The explosion generates a spike in the underwater pressure which is similar to a ping at all possible frequencies, it's the most useful type of ping, but can only be used occasionally because it requires a small bomb for each pulse.

Modern  diesel electric subs are very quiet when running on battery power underwater and going slow.  The explosive type active SONAR is good at detecting these subs.


The word sonobuoy is a  portmanteau of sonar and buoy according to Wiki.  The first U.S. sonobuoy was the CRT-1 used in W.W.II.  Like the Mk 24 "Fido" Mine (Wiki) it could only hear cavitating propellers.

Submarines Diving

In most movies about submarines there is the diving practice where the captain says "Dive . . . Dive . . .  Dive" and you hear a Klaxon horn (Wiki) sound.  A big thing is made of timing how long it takes to dive to some depth.  This comes about because aircraft specify how they turn by how long it takes to fly a full circle. For medium size airplanes this might be two minutes.  Note the rate of turning is specified by the time for a circle, not bank angle or the diameter of the circle.  So if an aircraft flies over a submarine and makes a tight circle to come back to attack it a second time the submarine has maybe 2 minutes to dive to safety.

This emergency dive process will go faster if the submarine is full speed ahead since there are some similarities between aircraft and submarines in the sense of how they respond to the elevator.  At full speed ahead the propeller(s) will cavitate (Wiki) which makes a lot more noise than normal running.  This extra noise was needed in order for the CRT-1 Sonobuoy and the Mk 24 "Fido" Mine (homing Torpedo) to work.

Types of Sonobuoys

ADAR: Advanced Deplorable Acoustic Receiver
ADLFP: Advanced  Deplorable Low Frequency Projector
ALFEA: Active Low Frequency Electro-Acoustic
BARRA: means Listening in an indigenous Australian language - The Barra Sonobuoy System, Barra Sonobuoy Design, horizontal array
BT: Bathythermograph
CAMBS: Command Activated Multi-Beam Sonobuoy
CASS: Command Activated Sonobuoy System
CFS: Command Function Select (set function with 2-way radio when buoy is in water)
CO: Calibrated Omni type acoustic sensor (5 - 20 kHz)
CSO: Constant Shallow Omni type acoustic sensor (30 - 5000 Hz)
DICASS Directional Command Activated Sonobuoy System
DIFAR: DIrectional Frequency Analysis & Recording type acoustic sensor (5 - 2400 Hz)
EER: Extended Echo Ranging - uses small explosion as sound source see patent 2402391
EFS: Electronic Function Selector (RF Chan, Life, Depth, Sensor type, AGC)
HIDAR: High Dynamic Range DIFAR
LOFAR: LOw Frequency Analysis & Recording - low cost, the waterfall display good for classifying a contact
RDRH: Rotating Directional Receiving Hydrophone
REFS: optical Remote Electronic Function Select (either while in launch tube (easy) or in water (requires laser))
RO: Range Only
The word sono-buoy is based on sound and a floating object.  See the CRT-1 web page for some history on acoustic sonic buoys.

Sonobuoys (Wiki) have been around since about May 1941 when P. M. S. Blackett, head of the British Admiralty committee for antisubmarine measures, proposed the idea.  In June 1942, the AN/CRT-1 became the first operational sonobuoy which was launched from a ship in a convoy, and on July 25, 1942, the first successful launch of a sonobuoy from an aircraft was made from a U.S. Army B-18 bomber (Wiki). (from: Not Ready for Retirement: The Sonobuoy Approaches Age 65 by Holler, Roger, Horbach, Arthur, McEachern, James).

  They are nomenclatured SSQ-nn.  They are a part of anti-submarine warfare (Wiki).

"All sonobuoys currently in inventory are normally launched from standard A-size tubes via pneumatic, free fall, or a Cartridge Actuated Device (CAD).  Shipboard personnel may also launch them by hand or Over the Side (OTS). All are powered by either salt water activated magnesium or silver chloride, lithium chemistry, or thermal batteries and are designed to scuttle at some point after usable or selected life expires."  from Approved Navy Training System Plan, for the Consolidated Sonobuoys.  N88-NTSP-A-50-8910B/A SEPTEMBER 1998

There's a problem with airborne sonobuoy receivers being used with MAD.   MAD works best when the plane is flying at about 500 feet.  This is also true for the periscope detecting RADAR.  BUT . . . .
The sonobuoy receiver will have relativity short rang when the plane is at 500 feet.  Much higher would allow better sonobuoy coverage.  Not sure what's an optimum altitude for dropping sonobuoys.   The new Navy P-8 (Wiki) no longer uses MAD and flies much higher, both for more sonobuoy area coverage and for better fuel consumption than it gets when flying low.  The P-8 has the AN/APY-10 RADAR (Wiki) but as far as I can tell it doe not work as well at high altitudes because the ocean surface scatter gets poorer at higher altitudes.  The poorest result is looking straight down on the water.

CNU-239/E Shipping Tube 

This may be the standard shipping container for A size sonobuoys.  It's 45" long and an octagon 6-3/4" across the flats.  One end unscrews and when shipping the cap is tapped to the main body.  The weight depends on what model in inside.
CNU-239/E Sonobuoy
                  A Size Shipping Tube

Transport Canada SU 0850 makes provision for shipping experimental sonobuoys in this container.
But there are limitations:

(a) all the dangerous goods are contained within the aluminum body of the experimental sonobuoy described by drawings no. 200896, 200898, 200702, 200671, 200836 and 200837 deposited by Ultra Electronics Maritime Systems, a division of Ultra Electronics Canada Defense Inc. on Transport Canada's Transport Dangerous Goods Directorate file A 4069-0850;

(b) the sonobuoy contains a single UN0454 Igniter having a net explosive quantity equal to or less than 0.15 g;

(c) the sonobuoy contains a maximum of 2 cylinders of UN1013, Carbon dioxide, each having a capacity equal to or less than 0.120 L;

(d) the sonobuoy contains a quantity equal to or less than 40 "C" size lithium batteries that meet the requirement of paragraph (1) of Special Provision 34 of Schedule 2 of the Transportation of Dangerous Goods Regulations;

(e) the sonobuoy is packaged in the military performance specification plastic shipping container type CNU-239/E specified in the drawing 012-159-0009-00 deposited by Ultra Electronics Maritime Systems, a division of Ultra Electronics Canada Defence Inc. on Transport Canada's Transport Dangerous Goods Directorate file A 4069-0850;

A Size

Modern sonobuoys have an outside diameter of 4-7/8" (fit 4-15/16" launch tube commonly called 5 inch) and are 1 yard long (36").  The max weight is 39 pounds. 
This is a convenient size for one man to handle on a P-3 aircraft (Wiki).  The larger sizes are not easy to handle.  There are smaller sizes based on getting some integer number of them inside the A size outline.  3 each is called "F" and 2 each is called "G".  The other sizes are pretty much not used in volume.


A hydrophone (Wiki) is the common sensor for sonobuoys and is typically deployed at 20 meters (65 feet: shallow) or 120 meters ( 328 feet: deep).  A sonobuoy might have 50 depth settings that can be set prior to ejecting it from an aircraft.  This is important because of what's called the thermocline (Wiki) which is where the temperature of the water changes rapidly.  This changes the speed of sound (Wiki).  This causes the sound to change direction just as light will be bent by a change in refractive index (Wiki).  And just like light there's conditions where the bending acts like a mirror and all the sound (or light) is reflected off the layer instead of just changing angles.  So if the hydrophone is on the wrong side of the thermocline it may not hear a sub that's on the other side.

Service Life

The service life can also be programmed prior to launch for 1, 3 or 8 hours.  After that time the sonobuoy will sink to the bottom.

Radio Transmitter

A VHF vertical whip antenna is used.  One feature of this type of antenna is that there's a null directly above the buoy so when an aircraft directly overflys the buoy there's a characteristic signal drop out.  This allows confirming the buoy location.  The 1 Watt transmitter is FM modulated and covers an audio bandwidth of 10 Hz to 20 kHz (about the same as a Hi-Fi system or entertainment FM radio).  Note that there is no provision to hear the 37 k Hz ping made by Cockpit Voice Recorders or Flight Data Recorders.  The FAA and Navy need to coordinate this.

Sonobuoy Receivers & Radio Channels

See the VHF part of the Frequency Assignment table for some common ways the spectrum is used.  For example, FM broadcast band is 88 to 108 MHz, 108 to 136 MHz is reserved for aircraft communications and navigation.  136 to 174 is called the High VHF band (the common "Scanner" band), the old analog TV channel 7 was 174 to 180 MHz.

In the book US Naval Weapons, Norman Friedman, 1983 (Ref 19) it's mentioned that during W.W.II the CRT-1 operated in the frequency range of 67 to 72 MHz and that post war sonobuoys operated in the 162.25 to 173.5 MHz range. 

Generation Zero

The CRT-1 Sonobuoys started out working in the VHF low band.  First with six channels between 62.9 and 66.9 then another six channels were added in the 67.6 to 71.7 MHz range.  That's a total of twelve channels.  This was during W.W. II.

Note:  The eBay listing for a sonobuoy receiver "R-156/ARR-16B Sonobuoy Receiver 62-72 MCs." is in error by leaving off the "1" in front of the frequency.
R-156/ARR-16B covers 162 - 172 MHz.  It turns out the eBay listing was correct.  Note that the new VHF high band is pretty much 100 MHz higher than the prior VHF low band.

1st Generation

It appears that the first generation sonobuoys only had 16 channels spaced 0.75 kHz apart between 162.25 and 173.50.  This was probably done using a single crystal in tube type electronics circuit.

2nd Generation

At some point (When?)  the channel spacing was cut in half.  At that time to maintain channel number comparability with the old system, the new channels were added in between the old channels as shown in the table. (chan 1) 162.25 to 173.50 with spacing of 0.375 MHz.
The R-1170 ARR-52A sonobuoy receiver has 31 crystal controlled channels.
This is the time frame of NAVAIR 28-SSQ-500-1 (1976).
41, 41A, 41B, 38, 50, 53, 57, 62
12, 14, 16
3, 5, 7
47A, 47B
1 to 12

3rd Generation

At some point (1980?) the total number of channels was increased to 100 (or 99?) by adding channels starting at 136.000 MHz (chan 32) and going to 161.125 (chan 99) with the same 0.375 MHz channel spacing.  Is there a channel 00?
So the band plan in frequency order is,  the new lower frequency channels from 136.000 to 161.125, skipping 161.500 and 161.875 (Why?), then the 2nd generation channels from 162.250 to 173.500 MHz.

USQ-46 (USQ, below)

The USQ-46 receiver has 3000 channels with a 6.25 kHz channel spacing.   
If the received frequency is below 162.000 MHz then the Freq_MHz = 145.525 + <chan#> * 0.00625,
if the frequency is equal or greater than 162.000 then Freq_MHz = 162.000 + <chan#> * 0.00625.
So there's a strong sonobuoy flavor to how the USQ-46 does channel assignment.
If you know about this, tell me.

Black Box

This is a beacon transmitter that just transmits a narrow pulse in the sonobuoy RF frequency range.  But, the signal requires a receiver with about a 150 kHz channel bandwidth.
Since the only information it sends is it's center frequency, probably one of a small list of possible frequencies and one of two possible duty cycles the process gain is extremely high. 

During the Vietnam era there were airplanes circling over areas where ground based sensors were placed to relay the VHF sensor signals to a ground station (Wiki).  This page was made because of the similarity of ground based intrusion sensors and sonobuoys.  They both work the same way and both have the same reception requirements.

My guess is that today there is a satellite system doing the same thing.  This system would receive in the 136 to 173 MHz range and use digital IF processing, similar to what's done in the HP 4395A combined spectrum network and impedance analyzer.  If that was the case then it would be straight forward to have the ability for this receiver to receive not only sonobuoy signals but also the waveform used by the Black Box.

This makes sense in that the system would have world wide coverage without the need to have planes circling 24/7 like in Igloo White.

The WiNRADiO MS-8118/WSB Sonobuoy Telemetry Multichannel Receiving System (WiNRADiO) covers 136.000-173.500 MHz (custom frequency ranges available) with an IF bandwidth of 30 kHz @ -6 dB.
They also have a WiNRADiO AX-61S Sonobuoy Telemetry Antenna that covers 135 to 175 MHz.
The G315i receiver can be ordered with an optional hardware wide band demodulator that's the same as in the sonobuoy receiver: WR-G315i Receiver Options or for the WR-G315e Receiver Options .
Note the black box beacon transmitter may be associated with the SEAL Delivery Vehicle (Wiki: SDV).
That would be perfect for receiving the Black Box signal (thanks to Chip Veres) for letting me know about the MS-8118.  But this raises a new question, what else generates such a wideband signal?

The transmission frequencies of some black box units are: 164.5375 & 164.5875 MHz.  Note neither of these is on channel 4 (164.50 MHz) and they differ by 50 kHz, not likely an accident.

Distributed Sensor Networks, Second Edition: Image and Sensor Signal Processing (Chapman & Hall/CRC Computer and Information Science Series)
Iyengar, S. Sitharama- book on order 14 Nov 2015 has info on Igloo White and may have some insights into the satellite system?

Sonobuoy Frequency Table

Chan Freq Chan
6 166.00 11
162.625 22
166.375 27
166.75 12
163.375 23
167.125 28
167.50 13
164.125 24
167.875 29
168.25 14
164.875 25
168.625 30
169.0 15
165.625 26
169.375 31


Channel 15 (172.75 MHz)  is used as an emergency search and rescue frequency.

Command Function Select (CFS)

The aircraft can transmit to the sonobuoy to change the commands while it's floating in the water which is much better than the old way of making the command decisions prior to launch.
The UHF frequencies used for this are: 282.900, 291.300, 291.400, 291.500 MHz

Directional Frequency Analysis & Recording type acoustic sensor (DIFAR)

These buoys use directional hydrophones (Wiki) covering 5 or 10 Hz to 2400 Hz combined with a magnetic bearing sensor and transmit this information.
They can be used to passively listen, to listen for reflected pings or the shock wave from a small explosion.
Whale researchers use them (Tools > DIFAR Sonobuoys).

Because the lower frequency limit is below Hi-Fi audio, consumer grade tape recorders could not be used so instrumentation type recorders were used.

With the advent of Digital Audio Tape (DAT) recorders the DIFAR signal could be recorded on a DAT tape.
The following is a frequency spectrum of the DIFAR signal with a voice channel added for use with a DAT tape recorder.
            Spectrum of the DIFAR signal with a voice channel added for
            use with a DAT tape recorder
Analog circuitry, like using the LM1496 Balanced Modulator-Demodulator can be used to manipulate these signals.
Note seismic sensors (geophones) respond to frequencies below 10 Hz so there's an overlap with DIFAR and other hydrophone frequencies.

DIFAR Patents

3116471 Radio sonobuoy system, Jesse J Coop, Dec 31, 1963, 367/3, 367/5, 367/113, 367/101, 367/126, 367/115, 318/638 -  In the present invention a multi-beam directional hydrophone is utilized in a radio sonobuoy system whereby an immediate quadrant location and an accurate distance measurement of a reflecting object from the multi-beam directional sonobuoy can be obtained from a single pressure pulse generated in the water area of interest.  - DIFAR

3987404 Underwater Direction Finding System is the patent that defines how a directional (the DI in DIFAR) sonobuoy can be made.

3987404 Underwater Direction Finding System, Sanders, (filed: Nov 3 1967) Issued: Oct 19, 1976, 367/3; 367/125; 367/126 -
"An underwater direction finding system includes a pair of directional hydrophones and a compass in a novel arrangement which associates the signals from all three elements with a single subcarrier.  Subsequent demodulation of the subcarrier signals in an airplane or ship then provides directional information directly referrenced to the earth's magnetic coordinates."
US2754493 Indicator for Sound Direction Finder
Feb 4, 1955 1956
US2837730 Deflection Method for CRT
Aug 4, 1952 Jun 3, 1958
US2867788 Object Locating Systems (sub hunting)
Feb 27, 1943 Jan 6, 1959
US3022462 Frequency Modulation Detector System
(see below)
Jan 19, 1953 Feb 20, 1962
US3148351 Directional Hydrophone System
(see below)
Jun 12, 1961 Sep 8, 1964
US3160850 Underwater Locating Apparatus
(Glomar Explorer?)
Dec 27, 1960 Dec 8, 1964
US3176262 Directional Sonar Systems
(dipping SONAR)
Apr 6, 1960 Mar 30, 1965
Referenced by:

US4872146 May 23, 1988 Oct 3, 1989 Canadian Patents & Development Limited Method and apparatus for simulating phase coherent signal reflections in media containing randomly distributed targets
US4879694 Mar 4, 1988 Nov 7, 1989 Rockwell International Corporation Difar demultiplexer circuit
US5253223 Apr 27, 1992 Oct 12, 1993 Den Norske Stats Oljeselskap A.S. Seismic device
US5265066 Apr 27, 1992 Nov 23, 1993 Den norske stats oljeselskap a.s Seismic cable
US5442590 Apr 27, 1992 Aug 15, 1995 Den norske stats oljeselskap a.s Seismic cable device
US6108270 Jul 6, 1999 Aug 22, 2000
Torpedo seeker head having directional detection independent of frequency
US6622647 Jun 26, 2001 Sep 23, 2003
Active noise cancellation for a torpedo seeker head
US8059485 Jun 4, 2008 Nov 15, 2011 NEC Corporation Communication system, information collecting method and base station apparatus

3461421 Advanced Direction Finding Sonobuoy System, (Collins Radio), Aug 12, 1969, 367/124; 367/3; 367/6; 367/125; 367/126; 367/128
2898589 Hemispherical Acoustic Phase Compensator, F.R. Abbott, Aug 4, 1959,
3022462 Frequency Modulation Detector System, Philco, Feb 20, 1962, - sonobuoy to aircraft
sonobuoy includes mag bearing and hydrophone.

3148351 Directional Hydrophone System, Bartlett Labs, Sep 8, 1964, 367/125; 367/3; 367/124
3239799 Sonar Directional Beam Focusing System, GE, Mar 8, 1966,
Referenced by:

ignee Title
US4078222 Nov 20, 1969 Mar 7, 1978 The United States of America as represented by the Secretary of the Navy Direction determining apparatus
US4371957 Dec 12, 1969 Feb 1, 1983 Her Majesty the Queen in right of Canada, as represented by the Minister of National Defence Antisubmarine warfare system
US4604733 Jan 3, 1984 Aug 5, 1986 Westinghouse Electric Corp. Apparatus for determining range and bearing
US4653033 Oct 4, 1984 Mar 24, 1987 Thomson-CSF Goniotelemetry system
US4691305 Sep 5, 1985 Sep 1, 1987 The United States of America as represented by the Secretary of the Air force Automatic attenuator for sonobuoys
US4872146 May 23, 1988 Oct 3, 1989 Canadian Patents & Development Limited Method and apparatus for simulating phase coherent signal reflections in media containing randomly distributed targets
US4914734 Jul 21, 1989 Apr 3, 1990 The United States of America as represented by the Secretary of the Air Force Intensity area correlation addition to terrain radiometric area correlation
US5859915 Apr 30, 1997 Jan 12, 1999 American Technology Corporation Lighted enhanced bullhorn
US5885129 Mar 25, 1997 Mar 23, 1999 American Technology Corporation Directable sound and light toy
US7088830 Mar 18, 2002 Aug 8, 2006 American Technology Corporation Parametric ring emitter
US7109789 Jan 21, 2003 Sep 19, 2006 American Technology Corporation Modulator—amplifier
US7224219 Sep 18, 2006 May 29, 2007 American Technology Corporation Modulator-amplifier
US7564981 Oct 21, 2004 Jul 21, 2009 American Technology Corporation Method of adjusting linear parameters of a parametric ultrasonic signal to reduce non-linearities in decoupled audio output waves and system including same

Directional sonobuoy, Russell I. Mason, John R. Dale, Secretary Of The Navy, FIled: Dec 19, 1974, Pub: Sep 12, 1978, 367/171, 441/1, 441/28 - 

Earth's Field Magnetic Detectors

Also see my Flux Gate patents web page.

2252059 Method and a device for determining the magnitudes of magnetic fields, Gustav Barth, Priority Dec 24, 1936, Pub Aug 12, 1941 - rod fluxgate
2560132 Unbalanced magnetometer, Schmitt Otto H, Jul 10, 1951, 324/255, 340/870.33 - second harmonic
2488341 Detection system, Thaddeus Slonczewski, Bell Telephone Labor Inc, Nov 15, 1949, 324/246, 340/870.33, 324/254, 324/253 - moving parts
2485931 Magnetic field strength indicator - no moving parts
2468968 Magnetic field strength indicator
2027393 Cathode ray device
2047609 Magnetic field direction and intensity finder
2053154 Direct-current indicator
2438964 Magnetic field detector - second harmonic magnetometer

Magnetic buoy

2397137 Magnetic controlling device, Glennon James B, Maltby Wilson R, Sellman Albert H, filed Jun 25, 1941, pub Mar 26, 1946, 340/850, 324/259, 340/551, 102/417

2644243 Control compass, George E Breeze, Russell I Mason, Us Navy, Filed: Nov 20, 1944, Pub: Jul 7, 1953, 361/280, 33/363.00Q -  for use in sonobuoy, eliminates vertical component of Earth's mag field for more accurate mag bearing (for: DIFAR)    

Magnebuoy, Ramond C Waddel, Filing date Mar 31, 1960, Publication dateAug 25, 1970 (maybe withheld secret), 340/852

Reserve Batteries

Reserve batteries have the electrolyte and anode separated.  This allows them to be stored for more than a decade and still retain their full capacity when activated.  Example applications are hearing
aid batteries, artillery shells and sonobuoys, weather balloons, torpedoes.  Also see Proximity Fuze Reserve Battery glass bulbs (Christmas tree lights)

Salt water activated magnesium

Because of the green particles that can be seen on the black plastic I suspect the chemistry is one of the following in the SSQ-53B:

Reserve Battery Patents

A reserve battery is one where the electrolyte is stored seperated from the electrodes.  They can sit for decades and when activated (heat, water, gas, mechanical force) are then a battery.
Wiki: Water-activated battery

2474716 Salt-water battery, John T Beechlyn, Submarine Signal Co, Filed: Sep 18, 1944 (5 year delay), Pub: Jun 28, 1949, 429/82, 429/94, 429/119 - light buoy.  Iron and Magnesium
2590584 Sea Water Battery, Bel Tel Labs, Mar 25 1952, 429/119; 429/152; 429/231.6 - silver chloride on silver & magnesium electrodes in salt water.
2669596 Reserve Battery Enclosure, Navy, Feb 16 1954, 429/8; 116/1; 429/119 -
2699461 Defered Action Battery, Burgess, Jan 11 1955, 429/119; 429/152; 429/162 -
2715652 Electric Battery for Airborne Equipment, Eagle-Picher Co, Aub 16 1955, 429/118; 429/152; 429/162 : -40 to 160 def F operation
3178316 Reserve Battery, Servel Inc, Apr 13, 1965, 429/119; 429/130; 429/210 -
3767933 Power Supply having a Plurality of Power Sources that are Sequentially Placed on the Load One at a Time, Oct 23 1973 307/48; 307/66 -
3966497 Seawater Battery, ESB Inc, Jun 29 1976, 429/119 -
4601961 Bilaminar Seawater Battery, Navy, Jul 22, 1986, 429/119; 429/127 -
5395707 Environmentally safe water-activated battery, ACR Elec, Mar 7 1995, 429/119; 429/128; 429/130 -

Salt water activated silver chloride

2564495 Deferred action primary battery, John B Mullen, Burgess Battery Co, Filed: Feb 27, 1947, Pub: Aug 14, 1951, 429/119, 429/152 - plain water activation, for radio B+  
2637756 Deferred action battery, Joseph J Coleman, Milton E Wilke, Burgess Battery Co, May 5, 1953, 429/119 -    
2655551 Magnesium-cuprous chloride reserve battery, Sec of Army, Filed: Jul 31, 1950, Pub: Oct 13, 1953, 429/119, 429/152 -
2699461 Deferred action battery, Milton E Wilke, Burgess Battery Co, Jan 11, 1955, 429/119, 429/152, 429/162 - water activated 

The following water activated batteries are probably all for uses relating to weather balloons or Radiosonde use.
BA-259 Water Activated Battery, NSN: 6135-00-635-6370, Eagle-Picher Ind. Colorado Springs: A: 1.5 & 6  Volts, B: 115 Volts

BA-292.AM Water Activated Battery, NSN: 6223-00-032-2387, Wisco Div, ESB Inc, Raleigh NC - for flashlight bulb on balloon
BA-380/AMQ-9, NSN: 6135-753-2276, Ray-O-Vac division, Mfg Co. Wonewoc, Wisconsin - for AMQ-9

Light, Emergency Sea Rescue Marker

A water activated battery powers a GE 131 flashlight lamp (1.3 Volts, 1.3 Watts, i.e. draws 1 Amp)

Stk. No. 6230-299-5653
Type J-2, with Water Activated Battery.
Spec. MIL-L-7396A(ASG) Application: Life Rafts
One Each    Item No. 4
Contract No. AF 30(635)-23525
Fulton Mfg. Corp. Mfg/Contr., Wauseon, Ohio
A-1 A8-  8/61 Reinspection Date.......... 8/64
Plastic Housing
Light Sea Rescue Marker
Type J-2   MIL-L-7368A(ASC)
Part No. N-45A
Fulton Mfg. Corp.
Caution: Do Not Remove Plug for


Fig 1  Box
                    Emergency Sea Rescue Marker Stk. No. 6230-299-5653
                    Type J-2, with Water Activated Battery. Spec.
                    MIL-L-7396A(ASG) Applicationi: Life Rafts One Each
                    Item No. 4 Contract No. AF 30(635)-23525 Fulton Mfg.
                    Corp. Mfg/Contr., Wauseon, Ohio A-1 A8- 8/61
                    Reinspection Date.......... 8/64
Fig 2 The Aluminum tube is to protect the plastic
light housing from being broken and is supposed
to be in place when deployed.
                    Emergency Sea Rescue Marker Stk. No. 6230-299-5653
                    Type J-2, with Water Activated Battery. Spec.
                    MIL-L-7396A(ASG) Applicationi: Life Rafts One Each
                    Item No. 4 Contract No. AF 30(635)-23525 Fulton Mfg.
                    Corp. Mfg/Contr., Wauseon, Ohio A-1 A8- 8/61
                    Reinspection Date.......... 8/64

Fig 3 There are loose crystals in the left end.
There is a small opening that shows up as a light
circle about where the rubber plug is located.
                    Sea Rescue Marker Type J-2 MIL-L-7368A(ASC)
                    Specification Part No. N-45A Fulton Mfg. Corp. U.S.
                    Caution: Do Not Remove Plug for Inspection.

Related Marker Lights:

A-7 AAF Flashlight Floating Identification (on One Man Life Raft web page)

Table of Sonobuoys

Naval Consolidated Sonobuoys @FAS -

5 vacuum tubes single channel FM transmitter between 67 & 72 Mhz.
See Roswell Connection below where this was used with "disk microphones" on Project Mogul
CANADIAN LANCASTER - AN/CRT-1 SONOBUOY SYSTEM - drawing of aircraft equipment & buoy
Naval History - RADAR - MAD and CRT-1
CRT-1A: 67.7 to 71.7 MHz
CRT-1B: 62.9 to 66.9 MHz
Jun 1942

Mechanical rotation of hydrophone (Ref 6)
Feb 1943

6 channels

separate web page (Differences to -1 and -1A? Let me know)

Ref 6
upgraded CRT-4
15 kHz to 17 kHz rotating directional
not UK SSQ-20

Ref 6

15 Feb 1955
1950 start of: Sound Surveillance System (SOSUS)


Julie explosive

Ref 6
Julie RO B-size, Tx 26 kHz to 38 kHz CW,

Ref 6
Julie  e 100 to 3000 Hz
19 Nov 1964
Jezebel-LOFAR 1960
19 Nov 1964
The BT sonobuoy is an expendable thermal gradient measurement sonobuoy that operates on one of three or one of 99 Radio Frequency (RF) channels. It consists of a thermistor (Wiki) temperature probe that descends through the bottom of the sonobuoy canister producing a continuous reading of temperature versus depth. The thermistor temperature probe will descend to 1000, 2000, or 2625 feet, depending upon the sonobuoy selected.

2017 Oct 11 - Navy places order for 166,500 anti-submarine warfare (ASW) sonobuoys - many types including -36, -53, -62, -101, 110, -125, Mk-84

2019 Dec 20 - 600 AN/SSQ-36/53/62 Sonobuoys to Denmark
Fig 36-01 Tubes
                          CNU-239/E Shipping, Launching & Housing
                          TubesShip: 7" x 45"

Launch: 5-3/8" x 39-1/4"

Housing: 4-3/4" x 35-7/8"
Fig 36-02 Launch Tube Cap - twist and lift.
                          Launch Tube Cap
Fig 36-03 Housing (what drops through air and lands in ocean
                          Housing (with plexiglass cap in place)

30day omni-directional LOFAR
(replaced SSQ-28)
10 to 6,000 Hz
31 chan
1 June 1961

Ref 6
single hydrophone, Rx: 10-6000 Hz (-41B Rx: either 10 to 10,000 or 10 to 20,000 Hz)
replaced both SSQ-23 & SSQ-28

late 1960s
Ref 6
(replaced SSQ-15 Julie explosive system) Tx (once every 10 seconds): 13 kHz to19 kHz
active ping omni directional range only
replaced by SSQ-50

replacedd by SSQ-41B

26 Feb 1981

Ref 6
CASS Command Activated Sonobuoy System, A-size, Pings only on UHF radio command. Tx: 6.5 to 9.5 kHz.
replace the SSQ-47
in 31 Second Generation Channel frequency plan.

Ref 6
31 RF Channels
10 Hz - 2.4 kHz
90 feet fixed depth


SSQ-53A 90 or 1000' depth
1 or 8 hours

fitted with microprocessor controlled EFS capabilities,
with three depth selections [100, 400 or 1000 feet],
three operating time selections of 1, 3 or 8 hours,
99 vhf channels.


Before inserting the launch tube into the aircraft chute the sonobuoy is programmed for operational life, channel number and depth by using the SET button.  If done incorrectly pulling the TEST plug for a few seconds will allow reprogramming.  Power for this comes from a couple of coin cell batteries.  The correct programming can be confirmed by pressing and holding the VERIFY button for a couple of seconds.

When forced from the aircraft chute by means of compressed air the lid is blown off the launch tube deploying the parachute on the metal sonobuoy housing.  The plastic launch tube stays in the chute.

When the metal sonobuoy (Fig 53-8)  impacts the water is starts to sink and water activates the reserve battery.  As soon as the battery has power (probably within a few seconds) the squib retaining the large spring allows an arm to puncture a compressed gas bottle inflating the buoy/antenna (Fig 53-17).  At the same time, depending on the programmed depth one or both rods (Fig 53-21) are driven down to set the amount of cable that will unspool controlling depth of the sensor.  A very short time later the three main components of the sonobuoy are separated as the metal outer housing is blown clear and sinks.

With power the radio transmitter begins to send it's signal.

The duration may be determined by a simple electric timer that shuts off the transmitter after the programmed time, or . . .  there may be some provision to do more?

Although very old I believe this unit would still work.

Fig 53-1
SSQ-53B Sonobuoy in Launch Container next
                          to shipping tube
Launch Tube 5-3/8" diz x 39-5/8" long
dated 5/87 - it's 12/11 now so this is just under 25 years old.
The shipping container probably was left on the ground.
If you know the deployment sequence let me know what it is.
Fig 53-2
Top: Channel (01 to 99), Duration (1, 3 or 8 hrs), Depth (90, 400 or 1000) Ft., Verify
                          Sonobuoy Settings Channel, Duration Launch
What was a transparent membrane has aged and is falling apart.  When intact would
provide a moisture barrier so the decissant  could keep the inside dry.
Fig 53-3
Sonobuoy Launch Container LAU/126A
NOO 83-86-C-0007
.OT 036
                          Launch Container LAU/126A
Fig 53-4
LAU/126A Launch Container Cap
Sonobuoy Launch Container LAU/126A Cap
Fig 53-5
Cap Off by removing 4 black plastic clips
SSQ-53B Sonobuoy Launch Container
                          LAU/126A Cap removed
It's not clear how the sonobuoy was programmed and in what order loaded into the aircraft launch chute.
Fig 53-6
Inside the Launch Tube, marked:
Caution: - Disengage before launch
Caution: Spring Loaded

                          Sonobuoy Launch Container LAU/126A after Cap
Fig 53-7
SSQ-53B Ready to launch (string holding spring snare)
The metal SSQ-53B housing is 4-3/4" O.D.
The label just to the right of the depth scale says:
WARNING Remove Plug Prior to Test
EFS Battery may be damaged if pins 1
and 2  are shorted or voltage is
applied across pins 1 and 2.

Voltage applied to pin 3 may cause high velocity ejection of top plate.
Reinstall plug before use.
SSQ-53B Sonobuoy Ready to Launch (string
                          holding spring snare)
Fig 53-8 With parachute deployed
                          with parachute out of body
The gray plastic cap was preyed off instead of submerging in water and dissolving the two metal links?

Fig 53-9
There are three functional parts.  The right is the antenna-buoy cover and receiver/transmitter,
the center is cable spools and the bottom (left) is the sensor.
                          three major assemblies
Fig 53-10
Three Major Components:
Left: Radio, Antenna, Battery
Center: cable
Right: Sensor

                          Major Components: 10 Radio, Antenna, Battery,
                          2) cable, 3) Sensor
Fig 53-11
Sensor, marked:
Sparton Corporation
Clock Number: 0358     Date 06/03/87
{bar code]
SIN: -67.1 db    COS: -68.4 db      OMNI: -72.1 db
the latter three parameters are related to the DIFAR aspect of the sensor.
The black cylinder hanging out the bottom is probably the omni hydrophone.
                          Sonobuoy Sensor label
Note:  There's a single green/white wire (cable) going to/coming from the sensor. I expect it's a small coax cable, but it remains to be seen.
Fig 53-12  Radio Buoy
SQQ-53B Sonobuoy Radio buoy top
Fig 53-13
With cap pulled off and buoy opened, but not inflated.
There appears to be small wire antenna with a resistor at the top.
                          w/buoy pulled out by not inflated
Fig 53-14  Test Socket & Memory Battery
Test Socket cap held by O-Ring, need big pliers to pull/twist it out.
There was a jumper plug  in the socket, more later.
SSQ-53B Test Socket & Memory Battery
Memory Battery and PCBs
There's a big spring that can puncture what's probably a good size CO2 cylinder in order to inflate the buoy/antenna.  There's what looks like a fusible link holding the spring in tension that could trigger the gas.

Also at the bottom of the PCB chamber there are a couple of lever arms that have a resistor wrapped around their ends.  If the resistor was exploded (over powered) then it would release these arms to do something (maybe control the depth through the cable spools?

The two coin cells are in the white plastic holder.  They provide about 6 Volts and are still good.

On the left board there are three red wires (Battery +), a bare stub where I wiggled off the battery + wire, and a yellow wire (to socket pin 3).  The bare wire at the top (just under the coin cells) that's soldered to a lug on the central metal plate is ground (same as the cast metal frame where the battery- wire connects.).
Fig 53-16
SSQ-53B Memory Battery & RF PCBs


Fig 53-17 Main Battery held to cylinder with double sided foam tape.
1 lb 11 oz. 4-1/4" hi x 3-1/8" w x 2-9/16" d (11 x 8 x 6 cm)
There is a hole on two sides just under the top cover to allow water to enter.
SSQ-53B Main Battery (dead)
This is a water activated reserve battery. 1986 Mfg date.
Fig 53-18
SSQ-53B Reserve water activated battery
                        Water Hole
In the other photos you can see green deposits on the inside of the radio/buoy black plastic.  I think that's because this reserve battery contains Copper in a form that allows it to escape.  This may be a limiting factor for the shelf life.  The Copper deposits are probably the result of the failure of the moisture proof membrane that covers the programming push button switches.   Once the moisture in the air gets to the reserve battery it's going to become a carrier for the copper and also will lower the battery capacity.

Idea:  Rather than depend on the moisture proof membrane (and Desiccant (Wiki)) to keep the reserve battery fresh, it should be in a compartment that's sealed until the metal housing is separated from the launch tube..

The two coin cells are still good condition after almost 25 years since this was manufactured.  

4262069 Lead chloride battery plate, John L. Devitt, Douglas E. Johnson, Robert S. Willard, Sparton Corporation, Apr 14, 1981 -
3468710 Sea water battery, Jerome Goodman, Philip I Krasnow, Nuclear Research Associates, Sep 23, 1969 -
2692215 Alkaline dry cell, Ruben Samuel, Oct 19, 1954 -
3005864 Sea water battery, Duncan T Sharpe, Bell Telephone Lab, Filed: Mar 29 (16 year delay), 1945, Pub: Oct 24, 1961 - maybe the Mk 18 torpedo (Wiki)
Fig 53-19  High Pressure Gas bottle to inflate buoy/antenna
SSQ-53B Sonobuoy buoy/antenna high
                          pressure gas inflation components
There are three PCBs:
Blue: modulator & RF exciter
Green:  I/O panel
Tan: RF Power Amp
Fig 53-20 Test Socket Message
SSQ-53B Test Socket Message
Socket Pin
to Gnd
to Bat+



1M 1M

Note 1: pin 3 is connected to one side of the squib that can cut the lanyard holding
the arm that will puncture the high pressure gas for deploying the buoy/antenna.

Pins 7 & 4 are connected to the ground bulckhead (0.0 Ohms).
Pin 3 is connected to the red battery wire (0.0 Ohms)

The jumper plug connects:
1 to 7
3 to 4

With the jumper plutg removed:
Red test lead to red battery wire (black lead to ground) = 1M00 Ohms
Black tet lead to red battery wire (red lead to ground) = 401k Ohms

Pin 1 is connected to the negative (black wire) leading from the two stacked coin cells).
The jumper plug connects pin 1 to pin 7.  Pin 7 is connected to the micro controller.  So these two pins relate to zeroing the programming.

If you have information on how the test socket is used please let me know.
Fig 53-32 Test Socket Schematic
See Fig 55-29 & Fig 53-31 for photo of Fuse 1 (LE  1A)
SSQ-53B Test Scoket Schematic diagram
A few of possible reasons for placing a fuse directly across the reserve battery.  One or more of them might be the reason. For Now I'll just remove the fuse.
1) Shorting the main power supply protects the squibs are from being
    fired by static or electromagnetic fields (like high power transmitters on board ships).
2) The reserve battery may like activate better when heavily loaded.  Note:  The
     BA-4386 Magnesium battery needs to see a heavy load in order to fully activate.
3) When the fuse blows the battery is delivering at least 1 amp and that surge current
     would next go to blowing the squibs.  This might be more reliable than ramping up
     the squib voltage.

Pins 5 & 6 each connect to one of the pins on the micro controller.  The Test plug (cable) probably has a jumper between pins 1 & 7 to connect the EFS (coin cell) battery thus powering the micro controller, and when it's powered up the test socket pins 5 & 6 can be used.  But for what?  Data In/Out, firmware programming, verification check sum, something to do with the hard wired option jumper to the upper right of the LCD housing? let me know.
 Fig 53-21 Buttons (now working) maybe because of cyclying the plug.
SSQ-53B EFS labels
Pressing and holding Verify for a couple of seconds will show the function settings.
To change the settings the plug must be removed for a few seconds.
Pressing SET starts the channel number counting 0 to 9 to 0.
Pressing SET fixes the tens digit and the units start counting pressing set fixes the channel number and the life bars start cycling.  Pressing SET sets the life and then the depth bars start cycling, pressing SET fixes the depth.  Now pressing Verify for a few seconds will display the function settings.

They were set for: 1 hr, chan 63 & 1000'
Now set for 3 hrs, chan 54 and 400'.
Fig 53-22 EFS LCD (plug shown installed)
SSQ-53B EFS LCD Verify
Fig 53-23 Depth Selection
The two levers are either in the position shown or they are pushed toward the center
to select how much cable is deployed.  The selection is made by the two blue plastic
actuators using a push (or pull) of the rod with the spring.  Note this rod is smooth and would not support a rotary motion.  Also the two levers in the bottom of the radio compartment work in an up or down fashion, not in a rotary fashion.  See Fig 53-9 and
a close up from it Fig 53-22 below..
SSQ-53B Depth Selection
Fig 53-24 Close up photo of depth selection blue plastic parts.
SSQ-53B depth selection blue plastic
Fig 53-25 Cutting Squib Wires
Three red wires have been cut deactivating the three squibs so DC power can be applied.
SSQ-53B Cutting Squib Wires to allow
                          power up
Test Socket Resistance readings after cutting the wires:
to Gnd
to Bat +


1.9 3-4
>1M 3-4

1M0 1M6
1.9 1-7
Gnd to Batt+ (w/0 Plug) = 1M0
Gnd to Batt+ (w Plug) =  0.7
There is still a dead short across the battery terminals!

pin3 is yellow wire to Battery + terminal (and red wires)
pin 4 is the metal frame (battery -) the black battery wire with the internal tooth lug.
This is confusing.
The hi pres gas squib is 36.2 Ohms.
One of the depth squibs is 18.5 Ohms (red to violet) not to ground.
The other depth squib is 18.3 Ohms (red to blue( not to ground.
These may be 1/8 Watt 18 Ohm resistors. Rated power would be at 1.5 Volts, 10X power at 4.7V, 100X power at 15 Volts, so if the battery is about 15 volts the resistors would fail mechanically.

Note the plug must be installed for the progrmming to work, so operation without the plug is not an option.   The plug has a jumper between pins 3 and 4 that is part of the path shorting the battery + and - terminals.

The coax feeding the antenna reads 42.7 Ohms.(resistor is Yel-Org-Blk-Red
Fig 53-26 Green Cable
10K0 Ohms either polarity.
This joint is located on the black plastic bottom plate of the Transmitter section.
White to White, Green to Green.
See: Fig 53-10 and Fig 53-12.
SSQ-53 Long Green 2-Conductor Cable
How to take apart the transmitter?  It may be possible to push everything out the bottom, but that would break the two push button switches.  Probably the best way is to saw from top to bottom at two places 180 degrees apart.
Fig 53-27
The switch buttons are mechanical working through a rubber boot and can be pulled
out of the plastic housing.
                          Removing Programming Switches
After letting the top sit overnight after applying some Kroil to the joint between the plastic housing and the metal plate with 0_ring seal the assembly pressed out the
bottom easily.  It was necessary to unsolder the antenna cable and the green wire to isolate the top section.
Fig 53-28 RF Amplifier
Tan PCB from top section
The antenna was connected at the top of this board where the notch is.
Gnd to the left and center to the right of the notch.
This is probably the Tx power amplifier and antenna matching/filtering board.
SSQ-53B Top Section Tan PCB
Fig 53-29  Command and Control Board
Green PCB from top section.
This is the digital board.
I doubt the micro controller is doing anything with the sensor data, so it's
probably running at a very slow clock frequency to conserve power.
So there's no need for a crystal for it.
SSQ-53B Top Section Green PCB
There are three 2N6724 2 Watt NPN Darlington transistors just to the left of the push buttons used for firing the three squibs.  The collectors go to the squibs and all three emitters are connected to the bulkhead ground plate.
Top: RF Amp board depth squib
Center: Synth board depth squib
Bottom: CO2

Maybe the transistor that blows the antenna squib is on the RF amp board?

Above the upper right corner of the black plastic LCD housing thre is a row of 6 holes and a jumper is installed in the right most of these.  
What option is this selecting?  Let me know.
Fig 53-30  Synthesizer and Modulator Board
Blue PCB from top section.
This board interfaces with the sensor package.
The crystal at the lower left is marked:
10.2985 MHz.  This is a non standard value, see my Crystals web page.
Maybe related to the DIFAR spectrum.
This board seems to be mostly analog in nature.
SSQ-53B Top Section Blue PCB
On the bulkhead plate at the bottom there are the two depth programming levers.
As shown the squibs (resistors) are intact and the lever is held in the down position.
The two rods are spring loaded and trying to lift up.  When the squibs are broken
the depth programming rods are forced up by their spring.

At the bottom right the green/white sensor cable can bee seen coming through a hole
and connectionto two pads.

All three squibs measure 500K Ohms to Bat+ and open to Ground.  So they are not causing the dead battery short.

The data codes on the ICs are 1984, 1985 & 1987.
6 Jan 2012 - New Idea about the direct battery short.
The short may be part of a Safe And Arm system that would prevent the buoy
from becoming active prior to an actual launch.  This may be a common system
used not only on sonobuoys but also things like countermeasures equipment like
flares and chaff dispensers.

If that's the case then something about the pneumatic launch would disable the short.
Fig 53-31  Fuse on digital PCB
This appears to be the cause of the dead short across the reserve battery terminals.
                          1 Amp Fuse Across (shorting) Reserve Battery
Power Up (with sensor disconnected, antenna attached)
For about 15 seconds the current is in the 30 ma range then jumps up to150 to 200 ma when the transmitter turns on.
After battery power the Verify button does not work.
The battery voltage appears on the green/white cable.
On reconnecting the green cable between the floating buoy and the sensor.
The resistance between the two wires and ground is: left: 1M and right 10k.
The resistance between the two wires and Batt+  is: left: 0.2  and right  1M
The resistnace between either wire and the sensor metal is an open circuit.
So as of 12 Jan 2012 it's still not clear how to be sure the polarity is correct to reconnect the sensor.
Thanks to Ugo in Italy there are two conductors in the cable, one supplies power to the sensor package (which has input filter caps) and the other is the audio signal to be modulated onto the transmitter.  Seawater forms a ground return between the floating transmitter and the sensor.  This is confirmed by the book The Ears of Air ASW. pg 241.


SSQ-53D Dwarf "G" size version of the B

SSQ-53D DIFAR only sensor, 90, 400 or 1000 feet, no CFS
5 Hz - 2.4 kHz
1/2, 1, 2, 4 or 8 hours
sea state 6



SSQ-53E Digital version
Additional hydrophone @ 45' for CSO
100, 200, 400 or 1000 feet
91.44 cm long

made by combining the
305 cm long
SSQ-53E & SSQ-57
NSN 5845-01-475-9870
adds CO hydrophone with directional units (replaces SSQ-57)
CFS Rx - single channel UHF
Tx - 96 selectable frequencies (136 - 173.5 MHz), 1W
90, 200, 400, 1000 Ft.

Ref 6
-57 Rx: 10 to 10,000 Hz, -57A Rx: 10 to 20,000 Hz.
See separate web page

late 1970s
Ref 6
DICASS Directional Command Activated Sonobuoy System
FM sweeps (FM-CW allows determining range (Wiki)
99 channel Third generation frequency plan.

99 channels

Command Function Select
Electronic Function Select
96 chan 136.000 - 173.500 MHz
CW Out: 6.5, 7.5, 8.5 or 9.5 kHz

Sonobuoy Tech Systems
Ref 6

Ref 6
VLAD (Vertical Line Array DIFAR) 1981

SSQ-77B " more hydrophones, 2 depths, 2 beams

" adds RF command function selection


early 1990s
Ref 6
ADAR Advanced Deployable Acoustic Receiver FY97

MIL-S-29593, 30 July 1997

30 July 1997

advanced EER ADLFP sound source
used with: ADAR sonobuoys like SSQ-53F, SSQ-77C and SSQ-101










SUS: Signal Underwater Sound

This is typically dropped from a friendly sub hunter aircraft in order to send one of a small number of predetermined messages to a submerged sub.  It uses audio tones around 3 kHz.
Like the CRT-1 Sonobuoy, ST-1 Bathythermograph and the T346/SRT SOS buoy is 3" in diameter so could be used from the Submerged Signal Ejector on a sub.

YouTube: Submarine Communications: "Signal, Underwater Sound (SUS) Mark 84" US Navy Training Film -
Mk-84 Mod 0
Got this on eBay with a fake nose cone that's been removed.  It's just the tail shell, but has markings:
DOD Code: SA-06
FSN: 1360-052-1480
Date Pkgd: (blank)
Contr. No.
Mfrg. 94117
Ser. No. (blank)
Wt. 6.5 Lbs. Nom.


There are 4 tapped holes for attaching the transducer/electronics package.  Adjacent to these holes are 4 holes 3/8" dia (total area: 0.44 sq in) that are the inlets for the water activated battery that's inside this tail section.  The center hole at the back is 7/8" ID (total area: 0.61 sq in, i.e. much larger than the inlet hold area. Why?).
Fig 1
SUS Signal
                    Underwater Sound Mk-84 Mod 0
Fig 2
SUS Signal
                    Underwater Sound Mk-84 Mod 0
Fig 3
SUS Signal
                    Underwater Sound Mk-84 Mod 0

(MK-84 MOD 1 SUS uses 3.3 and 3.5 kHz audio to generate 5 codes as messages to a sub.)
          Air to sub communications.
3.3 kHz
3.5 kHz






If there are standard meanings for these let me know what they are.
VLAD: Vertical Line Array Detector - long range ( 7 km (4+ miles)


2520814 Impulse emitting device, Bruce H Rule, App: 1945-02-03, Pub: 1950-08-29, - fires a series of blasting caps allowing the underwater position of a torpedo to be tracked.
2568712 Underwater signaling device, Charles F Bowersett, Kenneth L Baker, Carl A Axelson, App: 1947-12-18, Pub: 1951-09-25, 181/142 102/392 181/125 102/382 116/200 - "This invention relates to a signaling device and more particularly to an underwater explosive signaling device adapted to be dropped from an aircraft or launched from a life raft into a body of water, in which means controlled by hydro static pressure is adapted to explode the Signaling device when the device sinks to a predetermined depth. Within the body of Water."  A SOFAR Bomb.
2601245 Underwater signaling device, Charles F Bowersett, 1952-06-24, -
2989024 Submarine signal device, Sebastian J Tralongo, Vitro Corp of America, 1959-03-19 - colored dye pack
3056104 Underwater signaling and apparatus therefor, Kanski Leon M De, Theodore E Dinsmoor, Norman W Guinard, Pio F Martinuzzi, AMF, 1962-09-25, - sonar good to a few miles, this device 1500 miles.
3148618 Underwater signaling apparatus, Joseph D Richard, 1962-03-20 - used to determine optimum depth for SONAR by working with sonobuoys
3724374 Underwater sound source, Navy, 1962-04-27 - used with active sonobuoy, not as signal to friendly sub
4047148 Piston type underwater sound generator, Julius Hagemann, Navy, App: 1956-02-29 SECRET Pub: 1977-09-06, 367/143; 181/119; 116/27-

Also see the Vaisala  RD93 GPS Dropsonde which is another 3" diameter device launched from the same tube on an aircraft like the P-3.

Sonobuoy Aircraft Systems


R-2/ARR-3 see the CRT-1 Sonobuoy page.
CIA-46186 (RBF-1)

ARR-52 sonobuoy Aircraft Receiver

The ARR-52 was a 16 channel receiver and the ARR-52A is a 32 channel receiver.  (See: RxControl: ARR52A)


The internal modules have markings like:

Module 1
p/o R1170/ARR-52A 16 Tuning caps for crystal oscillators
Module 2
R-962 A/ARR-52

Module3 R-962 A/ARR-52
Module4 R-962 A/ARR-52
Module5 R-962 A/ARR-52
This suggests the ARR-52 (no letter) was made up of modules which were all marked R-962 A/ARR-52.
The R-962/ARR-52 has NSN: 5845-00-835-6218 and is 11.687x7.437x2.187", runs on 18 VDC, 16 channels (?) between 162.0 - 174.0, F9
The R-1170/ARR-52A has NSN 5845-00-999-6284 (4 March 1966)
Fig 1 Front Test Points: AGC, Disc & AFC.
Fig 2 Back antenna and system connectors.
Fig 3 Inside Top View
Fig 4 Inside Bottom View
Fig 5 Module 1 has 16 crystals on each side (32 total)
Fig 6 Module 2 Function???? (blank back side)
Fig 7 Module 3 Guess 5 MHz second IF (blank back side)
Fig 8 Module 4 Guess 26 MHz first IF
Fig 9 Module 4 Guess 26 MHz first IF
Fig 10 Module 5 Guess power supply & audio amp
DE-9P-C7  on DB-15 connector
Fig 11 Module 5 Guess power supply & audio amp
Fig 12 Chassis with 26 Mhz filter between Module 1 and Module 4.
5 MHz filter between Module 4 (cap to Module 1) and Module 3.
Fig 13 Module

CQ magazine October 1974, Conversion to 2 meters?
Some info from Radio Nerds:

ARR-52,A	R-962/1170 Sonobuoy Receiver  162.5-173.5 MC  AM-FM-Video 
 AM-2375,76/	ARR-52 RF Amps.
 ARM-53		ARR-52 Test Set
 AT-933/	ARR-52 Antenna (2 used)
 C-3109,10*/	R-962/ Control Boxes, 4 & 2 Signal Channels, 16 RF Channels
 C-4505,06*/	R-1170/ Control Boxes, 4 & 2 Signal Channels, 31 RF Channels NSN: 5845-00-999-6285
  C-4506  NSN: 5845-00-999-6286
MT-2258/ ARR-52 4-Receiver Rack MT-2259/ ARR-52 Shockmount for MT-2258/ PP-2479/ ARR-52 PS 115 VAC & 28 VDC in, -6, +18, +135 VDC out RD-53/ARH ARR-52 Bathythermograph Recorder U/W AM-1569/ARR-26 & IP-347/ SB-1084,85/ Signal Level Meters, 4 & 2 Channels

ARR-52 Patents

Channel select rotary solenoid - about 1-18" diameter.
2496880 Magnetically operated device, George H Leland, 1950-02-07, - first application was for air dropped bomb fuzes - "Ledex" is the brand name, Channel select rotary solenoid
2501950 Commutating switch mechanism, George H Leland, 1950-03-28, - Channel select rotary solenoid
2790153 Polarized electrical plug and socket connector having a plurality of contacts, Samuel L Arson, Cannon Electric Co, 1957-04-23- the original DB connector series? the prior patents used a rectangular array of contacts and something other than the contacts to prevent installing 180 degrees from the correct orientation, such as male and female threads on the screws.

General Sonobuoy Receiver Patents

3778728 Phaselocked-fm detector apparatus, R Nupp, EDMAC ASS, 1973-12-11, -
3845402 Sonobuoy receiver system, floating coupler, R Nupp, EDMAC ASS, 1974-10-29, -


Other Sonobuoy Aircraft Systems

An Aircraft Control Panel for ASA-20 Julie explosive echo ranging device & AQA-1 Sonobuoy Indicator/Tracker,
YouTube: Sonobuoy Indicator Group AN/AQA-1 Operation ~ 1961 US Navy; Lockheed P-2 Neptune (17:34) - works with SSQ-15 Range-only (RO) Echo-ranging, SSQ-20 Directional Listening (DL) or SSQ-2B Non-directional Listening (eXplosive echo Ranging: XR) sonobuoys.

Aircraft Sonobuoy Control
                  Panel ASA-20 Control
Drift - Compute - Reset

PDI (Pulse Doppler Indicator): BDHI (Bearing Distance Heading Indicator): Marker 1 to 6, GTP: Marker 1 to 6  Insert

ASA-20 or AQA-1                                                        ASA-20 or AQA-1
                                                  A-B: 1 to 6
                   A: Off to 6                   Data Release                B: Off to 6

ASA-31 Julie Control Panel
                  Julie Sonobuoy Control Panel
Julie Control

ASA-20 Sonobuoy Recorder "Jezebel".

The AQA-5 is a 4 channel paper chart recorder.
Youtube video: AN/AQA-5 Acoustic Charts Recorder 1:16 - monitors 4 sonobuoys in parallel
P-3 Orion Aircraft - Walk Around -

BDHI: Bearing Distance Heading Indicator
PDI: Pulse Doppler Illuminator
3582871 Ellipictal Computer System, Morris Snyder (Navy), Jun 1, 1971, 367/3; 367/107; 701/300; 708/801 - determines sub position using sonobuoys
AN/ARR-502 Multichannel Sonobuoy Receiver (data sheet, data sheet)

AQA-7(V)1/2 Directional Acoustic-Frequency Analysis and Recording System (DIFAR)

ASQ-114 digital computer has a memory loaded with a large number of sound profiles of submarines and radar- and radio signals for comparing ESM measurements

Forward Looking Infra Red (FLIR) replaced the Low Light Level TeleVision system (LLLTV)

ASR-3 Sonobuoy Reference System (SRS) - used multiple antennas to determine bearing to sonobuoy
Digital magnetic Tape System (DMTS) -

Integrated Acoustic Communication System (IACS) - sub coms

Litton LTN-72 navigation system used with the INS and Doppler navigation systems

ALR-66 (Wiki) ESM systems (Wiki) using the Adaptive Controlled Phased Array System (ACPA) (ESM is closely related to RWR)
Deinterleaver Technology for Future ESM systems, Dec 1992 NSWC - each pulse received from a single emitter can be agile in frequency, pulse width, pulse amplitude, pulse repetition interval, but not direction.  So using the Pulse Descriptor Word from the ESM sensor a future deinterleaver can sort out each emitter and differentiate between friendly and hostile emitters.  ESM systems mentioned:
IBM Associative Comparator
Anaren ESM Processor
ALQ-32 Inner Processor

Instantaneous Frequency Measurement (IFM) receivers are part of the ESM sensor.  But this type of receiver can have problems with two signals at the same time or with a CW signal anywhere in it's frequency range. The proposed configuration is to use narrow band receivers (many channels) and for each channel two paths, one for angle of arrival and the other for characterization of the received signal.

Bathythermograph (Wiki: BT)

In addition to being called a BT the term MBT (Mechanical BathyThermograph) is also used.
This is a device that measures the water temperature as a function of depth.  For example the SSQ-36 might first be dropped and the temperature profile recorded.  Then the ideal depth for the hydrophone determined and programmed into the sonobuoy.  Then the sonobuoys would be dropped.

The speed of sound in water depends on temperature so it slows down as the depth moves from the warm surface to deeper depths, but at some point the pressure caused by depth will cause it to speed up again.  The Thermocline (Wiki) can be detected using a Bathythermograph and that is the principle reason it's used related to submarines.

Bathythermograph (ocean measurements) References
1. Data Analysis Methods in Physical Oceanography, 2001
2. Scripps Institution of Oceanography: Probing the Oceans, 1936 to 1976, (1978 pub date)
3. Bathythermograph Data Analyzer, 5 June 1954 - AD043424 - takes up a 10' x 20' room.
4. An Ocean in Common: American Naval Officers, Scientists, and the Ocean Environment (see Ref 4 below)
5. Prediction of Sound Ranges from Bathythermograph Observations
,  (free online) 1944 confidential, 1967 declassified - how to prepare a message to another sub hunting ship about sonar conditions.  i.e. how subs can hide just below the thermocline and the maximum range that sonar can detect them.
On depth and temperature biases in bathythermograph data: Development of a new correction scheme based on analysis of a global ocean database, May 2010 (free online) - Niskin Bottles used for checking BTs since their depth is well known and if processed quickly the temperature of the water is also well known.
6. U.S. Naval Oceanographic Office Pub No. 607, Instruction Manual for Obtaining Oceanographic Data 1975 - Chapt. C "Measuring Water Temperature and Depth with a Bathythermograph" is all about this BT.
One of the things mentioned is the Nicopress swaged sleeve (Wiki) used to form a loop on stainless steel cable.  Home Depot calls these Everbilt Cable Ferrules
7. Lockheed-Martin Oceanographic Instruments - XBT/XSV datasheet.pdf, SSXBT/SSXSV datasheet.pdf,
8. Expendable Bathythermograph, Evaluation, DTIC_ADA045064.pdf - 78 pages, Dec 1964.  The unit from Francis Associates looks very much like the XBT-T4. Courtland B Converse worked for Francis Associates at one time and worked for a number of companies that have patents related to BTs.  Fig 2 shows 3-conductor cable.
Fig 13 Setup on Ship
Niskin Bottle as reference.
Expendable Bathythermograph, Evaluation FIg 13
The F.A. BT sink rate is a constant to a first order approximation.
This allows making a roll chart plot where the long axis is time (= depth).
They mention that the changing mass, because of un-spooling the cable,
will slow the sink rate as it goes down (is a second order effect).

The probe and it's shipping container have provision for 3 electrical terminals,
even if only 2 of them seem to be used on the XBT-T4.
USNS James M. Gilliss (T-AGOR-4) (Wiki)
A Biblography of Reports, Articles, and Data References Resulting from
Scientific Operations abord the Navy Pool (T-AGOR) Ships: 1963 Through 1969.

Glass Slides

The early slides were rubbed with Skunk Oil which was blackened using a flame.  Later slides were coated with  a thin film of metal.  This was probably done using the same technique of metal deposition (Wiki) later used in the semiconductor industry.  This may also be the method used for making reticles (Wiki) for Gun Sights like the Mk 20 Mod 4.  These later prepared slides may have had a graph marked on them to make reading much easier.

Fig 4
BATHYTHERMOGRAPH Dittmore & Freimuth

A standard 1" x 3" Microscope Slide (Wiki) is shown installed.
It is too long.
The correct size might be 1" x 1.7"

Prepared Slide image from Ripley's
                    Dittmore & Freimuth

Marked: Bathythermograph Shallow
From left to right calibrated 30 to 90 deg F.
From Top to bottom depth 0 to 180 (feet, meters)

There will be a plot of temperature v. depth as the Bathythermograph is
lowered to depth and another plot as it is pulled back up.

Dittmore & Freimuth BT

There may be another version that looks identical but has a depth range of 0 - 300 (450?) Feet instead of the 0 - 900 Feet range of this example.

Found this on eBay and recognized it from the patent drawings. 

This company lost a hydrophone contract with the Navy because of poor delivery and other issues, see:  B-153795, JUL. 17, 1964
This seems to be a company that bids on government contracts for a variety of products rather than a company that has a product line of standard products.
They do hold a number of patents.
Another Dittmore-Freimuth Bathythermograph is marked:  FSN 655-739-4360.  This unit has a much shorter tail section.
The glass slides may be NSN: 6655-00-676-7987.  Another eBay auction shows a wooden box to hold slides marked: Smoked Cards for Submarine Bathythermograph Type CTB 40131.

Fig 1 Loading sleeve closed.
BATHYTHERMOGRAPH Dittmore & Freimuth
What appears as a coil of Copper wire at the tail is actually a hollow tube filled with Xylene which acts like the liquid in a clinical thermometer, i.e. expanding when warmed and contracting when cooled.  That liquid drives a Bourdon Tube (Wiki) which in turn moves an arm with a stylus in a left or right motion.

Fig 2 Loading sleeve open (moved to front/left).
BATHYTHERMOGRAPH Dittmore & Freimuth

The microscope slide is connected to the pressure sensor consisting of a spring and bellows mechanism in the front which pushes and pulls the microscope slide front to rear.

Note there is a hole on the opposite side of the
Bathythermograph to allow a wooden dowel to be used to push out the scribed glass slide.
                    Bathythermograph, William M Ewing, Allyn C Vine, Us
                    Navy, Filed: May 27, 1944, Pub: Jul 11, 1950
2515034 Bathythermograph, William M Ewing (Wiki) Allyn C Vine (Wiki), Us Navy, Filed: May 27, 1944, Pub: Jul 11, 1950, 374/136, 73/300 - rapid response to temp & pressure (recording inside unit) that allows ship to be moving at 20 knots, rather than be stationary.

The nose is a weight to get fast decent.
The front contains the pressure sensor including an evacuated bellows that moves the glass slide front to back.
The middle contains the smoked glass slide used to record the data.
The rear contains the temperature sensor consisting of 40 to 60 feet to copper tube filled with Xylene (Wiki) with a melting point of -47.4 C (-53.3F). It moves the stylus side to side.
Fig 3
BATHYTHERMOGRAPH Dittmore & Freimuth
Markings visible after outer weight is removed.

0 - 900 Ft.
Ser. No. 15923
Mfr. 97188


Makes surface launched Expendable eXpendable BathyThermographs as well as models for use on submarines SSXBT.


This unit is a derivative of the Francis Associates BT mentioned in BT Reference 8.  It has the same shape.  It is paired with a launch tube (the other BT's tested in the reference used other methods).  The temperature precision of the Francis Associates BT was the best of those tested but it had an offset.

NSN: 6655-00-932-1353

These contain a Thermistor which has a non-linear negative temperature coefficient.  patent 3341757 & RE27103 are designed to address the problem of converting to a linear temperature output and compensating for the resistance of the very long fine Copper wire's resistance at different ocean temperatures.

Bathythermograph Reference 6 Covers the XBT in chapter C starting with paragraph C10 on page C-9.  This is for the first generation where there is a roll chart plot of temperature v. time.

Another problem is the rate of decent in the ocean.  This will not be constant because of the un-spooling of the Copper wire from the probe causes its weight to decrease with depth.  So assuming a constant decent rate will introduce an error.

While the label says "Patent No. 3,221,556" that first patent is for a single wire system that uses the sea as the return electrical path.  More likely is that patent 3339407 applies that provides for two wires.

This model is part of a common set of eXpendable BathyThermographs which also includes
Max Depth (m)




Deep Blue 760

The T-6, T-7 and Deep Blue (DB) models.
These do not contain a pressure sensor so depth is determined by the time since release and a known rate of decent.

patent number on the label: 3221556
Fig 1 In launch tube as received.  The rotational location
of the clip is important since it sets the location of the three electrical terminals behind the label.
Fig 2 Bottom cap pulled off and pin pulled.
Fig 3 Hole in nose allows water to flow inside
to get rapid response on temperature sensor.
Fig 4 Using Flashlight to see wire spool down launch tube.
Fig 5  Note space to the right of tail in launch tube for wire spool.
You can see wire spool in hole just behind metal nose with a
flashlight and your eye, not easy to photograph.
Fig 6 Three Terminals (note Index mark)
16.65 k Ohms at room temp.
The cream colored material is some type of wax. Probing near the outside edge finds a metal plate but if probe is too near the
center there's no contact, so the location of the tips black lines
is about a good place to probe.

Now in the refrigerator overnight to see the difference.
Fig 7  Thermistor (Wiki) recessed in nose hole. 
Small thermistor size means fast response time.
There is no electrical connection between either thermistor lead and the metallic nose.
Fig 8
Lockheed Martin Sippican, Inc.
[bar code]
SN 397657 DOM Made in Mexico, 06 / 26/ 06
NSN 6655-00-932-1353
Patent No. 3,221,556
Expendable Bathythermograph

XBT-T4 Resistance

In order to make some resistance measurements I first checked my refrigerator and freezer and found they were slightly warmer than the desired 40F (4C) and 0F (-14C) readings. 
Temperatures measured using Fluke 87V DMM with 80T-150U & Type-K thermocouple.
After some adjusting of the controls and waiting a day for the temperature to stabilize I'm now getting:

0F (-18C)
51.30 k
43F (6C)
22.87 k
68F (20C)
17.49 k

SSXBT Model ST-1 Bathythermograph

Submersible Ship (Submarine) launched XBT, i.e. SSXBT made by Sippican Ocean Systems.
When launched from an upward facing 3" signal ejector the complete unit floats upward.  The float separates from the lifting body and continues to ascend. When the float reaches the surface the probe and wire spool are released.

This is one of a number of devices that can be launched from the 3" launcher (signal ejector).
Fig 2 Label
                  Expendable Bathythermograph (SSXBT)
Fig 1 3" dia x 36" long
                    Expendable Bathythermograph (SSXBT)

Some Guidelines for the Submarine-Launched Expendable Bathythermograph (SSXBT) System (DTIC Oct 1981, 50 pages) The AN/BSQ-23 (older) and AN/BQH-7 (newer) have higher incidence of failure than the Bathythermographs used aboard surface ships.  This document is to help in recognizing when they have failed.  Typically used to measure ocean temperature v. depth in 100 foot intervals down to 2,500 feet.  This can be used a part of the launch solution for the Mk 48 torpedo.  It seems the sub needs to be at the surface to launch the ST-1.  Because of the hydrodynamics of the ST-1, it's rate of decent is known, it's possible to know the depth by the time since it was on the surface.  It should take 2 minutes 58 seconds to go from the surface to 2,500 feet.  If the sub enters a new ocean front (see map on pdf pg 18) the BQH-1 graph will show a change.  That can be compared to the SSXBT data to confirm correct operation of the SSXBT.  The appendix has 21 example plots each showing a different problem.

The AN/BSQ-23
4518915 Test device for expendable bathythermograph, Philip G. Danforth, Thomas G. Bucko, Kenneth R. Galliher, Joseph T. Lucia, Richard L. Miller, Timothy B. Straw,
Secretary Of The Navy, May 21, 1985, 324/750.01, 324/762.01, 374/E15.001, 374/134 - " provide a simulator for testing and calibrating a wide variety of XBT systems used on board surface ships and submarines...."

The BQH-1 Depth-Sound Speed can be used as a check on the SSXBT.  This plots the speed of sound (time delay for a fixed distance) v. depth (water pressure). Either temperature or sound speed units can be used, it's best to use temperature units to allow matching to the SSXBT data.
AD-758 085, Engineering Evaluation of Depth-Sound Speed Measuring Set AN/BQH-1 Manufactured by Dyna-Empire Corp. Garden City, New York.  Contract NOBSR-75772, Navy Underwater Sound Laboratory, New London, Connecticut, 10 March 1961.

Bathythermograph Patents

The early Spilhaus Bathythermographs were based on a stylus marking a microscope slide blackened soot.  This basic design went through many improvements.  It was deployed on a line and recovered to get the glass slide.  Note while each of these has a serial number and a custom made calibration chart for that serial number in order to convert the data on the glass slide to  depth and temperature.  That data was used to determine the Assured Range (AR) of a sonar system.  Note the sound is bent downward when the water gets colder with depth and when a submarine on the surface is beyond the AR distance it is invisible to the sonar.

The Submarine Bathythermograph (SBT) is built into the sub and records depth and temperature on paper cards.  The sound man will know from charts that contain BT data, as well as other data related to sonar, what to expect in the current operational area.  But to get a more accurate picture a deep dive with a fresh BT card in the machine or dropping a BT sonobuoy (SSQ-36 , ST-1 from the surface will give an accurate picture of the current conditions.  A lot more info on BT in An Ocean in Common (Ref 4).

Courtland B Converse worked for a number of companies that have patents related to Bathythermographs.

2331810 Bathythermograph, Spilhaus Athelstan F, Submarine Signal Co, Oct 12, 1943, 374/136; 374/143; 73/300 - separate temp and pressure mechanisms
2402143 Parachute pack, Arenstein Gilbert H, Sec of War, Filed: Jun 7, 1944, Pub: Jun 18, 1946, 244/138.00R, 455/99, 343/709, 244/151.00B, 343/889, 441/11, 367/4, 116/26, 455/96 - for sonobuoys with antenna through center of parachute.
2297725 Bathythermograph, Spilhaus Athelstan F, Submarine Signal Co, Filed: Aug 10, 1938, Pub: Oct 6, 1942, 374/136, 374/E01.3, 73/729.1 - marks smoked glass slide with pressure & Temp, Bourdon tube - prior to W.W.II, pull up to get plot

2515034 Bathythermograph, William M Ewing, Allyn C Vine, Us Navy, Filed: May 27, 1944, Pub: Jul 11, 1950, 374/136, 73/300 - rapid response to temp & pressure (recording inside unit) Bourdon tube During W.W.II - design separates pressure sensing from temperature sensing so they can be made and tested separately.

2629083 Expendable radiosonic buoy, Barkson Joseph A, Mason Russell I, Mcnary James C, Filed: Sep 21, 1944, Pub: Feb 17, 1953, 367/3, 343/709, 455/99, 441/33, 441/23, 343/705, 343/901 -
Method of ascertaining unknown data, Earl W Springer, Filed: Jan 2, 1946, Pub: Jul 20, 1954, 374/100, 356/393, 73/584, 367/99 -  the importance of depth v. Temp data for sonar. - uses optical comparison of a BT glass slide plot with a catalog of plots to get a rapid interpretation of the meaning in terms of SONAR.
2703009 Bathythermograph, Ewing William M, Vine Allyn C, Filed: Nov 28, 1945, Pub: Mar 1, 1955, 73/178.00R, 346/120, 73/712, 73/742, 374/E01.3, 73/299 - for use on subs 
2741126 Thermistor temperature profile recorder, Ernest R Anderson, Arthur T Burke, Navy, 1956-04-10 - drum of wire at surface - cable to thermistor
3098993 Sonobuoy-bathythermograph system, Coop Jesse J, Jul 23, 1963, 367/134, 374/E01.3, 340/870.17, 340/870.6, 367/185, 367/3, 374/E01.4, 73/170.34 - sound output that can be heard by sonobuoy.
3119090 Sea depth determination air survey means
3135943 Underwater thermometric apparatus, Welex Electronics, - sets off a small explosion at a specified amount of change in temperature.
3137264 Underwater towed vehicle, Ii Edward C Brainard, Courtland B Converse,
Endeco Inc, Braincon Corp, 1961-11-15, 114/244; 367/106; 114/243 -

3221556 Bathythermograph system, Campbell Walter Graham, Jr William Van Alan Clark, Courtland B Converse, (SIPPICAN OCEAN SYSTEMS Inc), 1965-12-07 - probe has diode in parallel with resistor, single wire w/sea return - marked on T4, XBT NSN: 6655-00-932-1353 - Main Sippican BT system 

                    Bathythermograph system, Campbell Walter Graham, Jr
                    William Van Alan Clark, Courtland B Converse,

                    Bathythermograph system, Campbell Walter Graham, Jr
                    William Van Alan Clark, Courtland B Converse,

                    Bathythermograph system, Campbell Walter Graham, Jr
                    William Van Alan Clark, Courtland B Converse,

                    Bathythermograph system, Campbell Walter Graham, Jr
                    William Van Alan Clark, Courtland B Converse,

                    Bathythermograph system, Campbell Walter Graham, Jr
                    William Van Alan Clark, Courtland B Converse,

                    Bathythermograph system, Campbell Walter Graham, Jr
                    William Van Alan Clark, Courtland B Converse,

                    Bathythermograph system, Campbell Walter Graham, Jr
                    William Van Alan Clark, Courtland B Converse,

CA1037290 Apparatus for measuring the properties of water, Walter G. Campbell, William V. Clark (Jr.), Courtland B. Converse, Buzzards Corp, App: 1963-02-06,

3209208 Mounting assembly for modular electronic units, Samuel A Francis, Arthur W Sinkinson, Courtland B Converse, Sippican Corp, 1961-08-14
Bathythermograph, Spark Wallace R, Douglas Aircraft Co Inc, Sep 20, 1966, 374/136, 340/852, 73/170.34, 374/E01.3, 73/292, 367/134, 374/142 - RF transmitter & matching receiver

3327968 Aircraft towed underwater skip probe, Courtland B Converse, Francis Associates, 1966-04-01, 244/3; 114/244; 174/69; 324/330; 367/106; 114/253; 244/1TD; 73/170.33; 331/36C - aircraft towed sonar probe

3339407 Oceanography probe, Walter G Campbell, W Van Alan Clark, Courtland B Converse, Sippican Ocean Systems, 1965-04-22, - bomb shaped drop probe with 2 wires

                    Oceanography probe, Walter G Campbell, W Van Alan
                    Clark, Courtland B Converse, Sippican Ocean Systems,
Through hole (5a) and blocked hole (5) versions.
                    Oceanography probe, Walter G Campbell, W Van Alan
                    Clark, Courtland B Converse, Sippican Ocean Systems,

                    Oceanography probe, Walter G Campbell, W Van Alan
                    Clark, Courtland B Converse, Sippican Ocean Systems,

                    Oceanography probe, Walter G Campbell, W Van Alan
                    Clark, Courtland B Converse, Sippican Ocean Systems,

3341757 Bridge circuit for determining the inverse of resistance, Dexter E Cate, Sippican Ocean Systems, 1966-07-11, -
RE27103 Bridge circuit for determining the inverse of resistance, Dexter E Cate, Buzzards Corp,
3349613 Aquatic probe, Samuel A Francis, Buzzards Corp, 1967-10-31 - works with submarine by adding float to nose of standard probe.
3388372 Determination of ocean sound velocity profiles, Witz Gerhard H De, General Precision, 1967-05-22
3389604 Temperature sensing device, George B Williams, Sippican Ocean Systems, 1965-11-05, - special thermistor to work in sea water and at depth.
3394583 Doppler shift systems and components therefor, James G Dongherty, Donald S Moseley,
Vitro Corp of America, 1965-02-16, - Ocean sounding probe
3408867 Temperature measuring sea water probe, insulated wire suitable therefor and method of making same, Charles G Henricks, Mieux William C Le, Sippican Ocean Systems, 1966-10-10, - " fine wire and particularly to wire coated with multiple alternate layers of epoxy and nylon enamel."
3401560 Oceanographic measuring and recording device, Samuel A Francis, Sippican Ocean Systems, 1965-04-07, - describes the 1-wire BT probe system.  Processed output on 80 column IBM punched card (Wiki).
3417619 Single wire measuring device for bathythermograph system, Samuel A FrancisBuzzards Corp (SIPPICAN OCEAN SYSTEMS Inc), 1968-12-24 -
System for measuring sound velocity in water as a function of depth, Cawley John H, Schiff Daniel, Us Navy, Apr 29, 1969, 367/131, 367/134, 73/597, 367/89 -  a sound projector, triggered by a surface ship sends a ping to the ships sonar which measures the time delay.  Knowing the depth and horizontal distance to the probe allows a direct readout of the sound velocity. 
Note in 1969 the ability to measure short time intervals was much poorer than today, so the length of the base line can be shortened from maybe 100 feet to something more reasonable like a yard so that the device could be permanently mounted on a ship or sub.
3469444 Launching apparatus, William H Ayer, Sippican Ocean Systems, 1967-07-17, - one wire spool stays in launcher and the other wire spool is part of the probe.
3479580 Apparatus including a conductivity probe for determining the salinity of water, Hoyt Clarke Hottel Jr, Sippican Ocean Systems, 1965-04-22, - makes use of their standard bomb shaped probe with a central hollow tube, alternating polarity current generators are connected to the single wire.
3483749 Bathythermograph system, Samuel A Francis, Sippican Ocean Systems, 1968-07-22, improves on 3221556 by using a current source and using both polarities in order to cancel out the resistance of the wire and sea water paths so more accurate.
3496525 Expendable transmission loss hydrophone system, Samuel A Francis, Sippican Ocean Systems (Buzzards Corp), 1968-05-29, - 3 wire system.
3504278 Bathythermograph testing apparatus, John A Lyons, Sippican Ocean Systems, 1968-03-12, - just tests wire by using two spools underwater to wind wire to simulate extending all of the wire.
3524347 Expendable bathythermograph for submarines and device for launching, Ralph P Crist, Navy, 1970-08-18

3535924 Bathythermograph system, Richard Bixby, Sippican Ocean Systems, 1969-09-11, - wire spool in probe and wire spool in launch container.  But instead of the hollow central tube it uses symmetrical grooves on it's nose to direct water to measuring devices in the tail.  Improvement on 3221556.  Smaller, lighter, sealed.
3552205 Apparatus for measuring properties of a fluid body from an airborne vehicle,
Samuel A Francis, Sippican Ocean Systems, 1968-07-24, - helicopter requires a 3-wire cable instead of the normal 1-wire probe.
3553639 Expendable sonar source, Daniel Schiff, Hoyt Clarke Hottel Jr,
Sippican Ocean Systems, 1968-08-09, - water hammer (Wiki) converted onto hi power sound
3588794 Underwater data acquisition device, Samuel A Francis, Sippican Ocean Systems, 1969-04-04, - sonar system
3605492 Preassembled model SXBT flotation device, George D Stohrer, John H Cawley, Richard P BerthiaumeDaniel Schiff, Navy, 1971-09-2
3561268 Expendable bathythermograph, Frank Massa, Dynamics Corp, App: 1969-01-14, - contains both pressure and temperature sensors, uses sound to send back data, not cable.
3349613 Aquatic probe (See above)
3038143 Telemetering depth meter, Dow Willard, Navy, App:1956-01-17, - Tubes, uses sound to send temp data. 13 citations.
3069573 Connector assembly for annular piezoelectric transducers, Eugene Van Liew, Navy, App: June 26, 1961, -
3135943 Underwater thermometric apparatus (See below)
3273393 Bathythermograph (see below)
4025847 Measurement system including bridge circuit, Ralph G. Washburn, Sippican Corp, 1975-08-27, -
Expendable bathythermograph for use under ice, Ralph P. Crist, Secretary Of The Navy, Aug 5, 1980, 73/170.29, 374/E01.018, 374/E01.004, 73/300, 73/170.34, 374/136 - a housing for the (SSQ-36?) that floats up and when it hits the surface or the bottom of the ice releases the (SSQ-36?).
4359285 Temperature measurement system, Ralph G. Washburn, Sippican Corp, 1982-11-16 - uses #38 9very fine) wire to get down to 10,000 feet - transistor oscillator circuit draws much less current than thermistor
4673363 Marine measurement device, Alan T. Hudson, David P. Gagnon II, David W. Johns, William J. Langenhein, Jr., Sippican Ocean Systems, 1983-06-15, -Sonobuoy with simple hydrophone,  maybe much larger than standard launch tube.
4854728 Seawater probe, George Baron, William H. Vreeland, Neil L. Brown,
Sippican Ocean Systems, 1987-05-18, - a glass sealed 2k @ 25C Thermistor is included with the probe with data measured when built.  An HP desktop computer (80 series?) is used to correct the as made readings when the probe is actually used.  Very similar to how Radiosonde cal works.
5046359 Underwater launched carrier, John L. Layport, Sippican Corp, Filed: 1975-01-24, Pub: 1991-09-10 - launched from sub, floats to surface, then descends

Niskin Bottle (Wiki) aka: Nansen Bottle

Used to get a sample of water from a known depth.

YouTube: General Oceanics: Setup of a Niskin Bottle, 4:06, -Parts of a Niskin Bottle, 1:44 -

2155442 Means for sampling a liquid, Douglas L Parkhurst, 1938-09-24, 73/863.01; 73/864.63 -
2314372 Sea sampler, Athelstan F Spilhaus, Submarine Signal Co, 1941-04-18, 73/863.01; 73/864.63; 73/863.31 -
3242740 Water sampler system, Shale J Niskin, 1963-05-31, 73/863.31; 374/102; 374/157; 73/864.67; 374/136; 73/864.62 -
3339417 Water sampling apparatus, Joseph D Richard, 1964-11-19, 73/863.31; 73/864.63; 73/170.29 -
3489012 Water sampler device, Shale J Niskin, 1967-07-17, 73/863.31; 24/115R; 74/2; 73/864.63 -
3537316 Underway water sampler, Richard L Stewart, Kenneth M Olson Jr, Leonard Walsh, US Navy, 73/170.33; 374/E13.012; 73/864.63; 374/157; 374/136 -
3625066 Water sampling apparatus, Michael L Greene, US Navy, 1970-03-30, 73/864.63 -

GB189900564 Sounding Apparatus for Purposes of Navigation, Zera Luther Tanner, John Bell Blish, 1899-02-11, -

Outdoor Intrusion Detectors based on Sonobuoy Technology

Link between Vietnam Intrusion Detectors and Navy

6 Sep 2019 Discovered the next 3 patents while looking for information on the RR-97/AL chaff brick.  The inventors of Navy Sonobuoy containers also invented seismic and acoustic intrusion detectors.  This is the link that was obvious 7 years ago in 2012, but now is confirmed.

3891865 Intrusion detector, Salvatore R Picard, Robert F Starry, US Navy, 327/37; 340/539.1; 340/522; 340/566; 340/539.14 - "A low-current detection device responsive to both audio and seismic input signals received over predetermined periods of time at preselected amplitude levels."
Publication number  Priority date  Publication date  Assignee  Title
US3139539A *1962-03-30  1964-06-30  Gen Electric  Control circuit producing output signal so long as input pulses occur within certain time interval
US3517316A *1966-03-22  1970-06-23  Res Instr & Controls Inc  Surveillance equipment and system
US3552520A *1968-02-27  1971-01-05  Us Navy  Detecting and transmitting system with interval timing means
US3569923A *1967-10-30  1971-03-09  Us Navy  Adaptive acoustic detector apparatus
US3585581A *1969-07-22  1971-06-15  Honeywell Inc  Seismic sensor apparatus
US3613061A *1968-08-29  1971-10-12  Bryant D Lund  Pressure-responsive, timed, electronic control apparatus and method
US3691549A *1970-12-02  1972-09-12  Sylvania Electric Prod  Signal processor
US3714622A *1969-12-12  1973-01-30  Us Navy  Adaptive agc system
Cited by
Publication number  Priority date  Publication date  Assignee  Title
US4604738A *1982-02-22  1986-08-05  Honeywell Inc.  Method and apparatus for classification of a moving terrestrial vehicle as light or heavy, compensates for different distances from vehicle to sensor by comparing the energy in the acoustic and seismic signals.
Publication number  Priority date  Publication date  Assignee  Title
US3585581A *1969-07-22  1971-06-15  Honeywell Inc  Seismic sensor apparatus
US3824532A *1971-09-27  1974-07-16  Us Air Force  Seismic signal intrusion detection classification system
US3891865A *1973-11-14  1975-06-24  Us Navy  Intrusion detector
US3903512A *1974-03-07  1975-09-02  GTE Sylvania Inc  Signal processor
US3984804A *1971-11-29  1976-10-05  Navy  Acoustic and seismic troop movement detector
US3995223A *1970-02-19  1976-11-30  Navy  Seismic-acoustic detection device
US4081785A *1974-02-13  1978-03-28  Air Force  Dual class amphibious target discriminator
US4090180A *1976-03-16  1978-05-16  Elliott Brothers (London) Limited  Vibration-responsive intruder alarm system
US4158832A *1961-06-19  1979-06-19  Army  Seismic apparatus for discrimination between track-type vehicles and wheel-type vehicles
US4271491A *1978-11-20 1981-06-02  Simpson Ronald R  Intruder alarm system
US4337528A *1972-12-13  1982-06-29  Air Force  Moving vehicle seismic target detector
Cited by
Publication number  Priority date  Publication date  Assignee  Title
US4953144A *1989-09-11  1990-08-28  Shell Oil Company  Third-party detection around pipelines
US5007032A *1990-06-08  1991-04-09  Honeywell Inc.  Acoustic alert sensor
EP0535570A1 *1991-10-01  1993-04-07  Rockwell International Corporation  Transient detection processing, especially underwater acoustic signal recognition
US5229765A *1991-05-08  1993-07-20  Halliburton Logging Services, Inc.  SP noise cancellation technique
US5737433A *1996-01-16  1998-04-07  Gardner; William A.  Sound environment control apparatus
US6385130B1 *2000-09-11  2002-05-07  Navy  Dual channel switch with frequency band limiting
EP1222445A1 *1999-10-06  2002-07-17  George W. Herndon  Seismic weigh-in-motion system
DE4212072C2 *1992-04-10  2002-09-26  Stn Atlas Elektronik Gmbh  A method of detecting and classifying sound sources, in particular of vehicles
WO2005034062A1 *2003-10-02  2005-04-14  Robert Bosch Gmbh  Method for the evaluation and temporal stabilization of classification results
US20070062289A1 *2005-09-07  2007-03-22  Luna Innovations Incorporated  Method and apparatus for acoustically weighing moving loads
EP1835308A12006-03-16  2007-09-19  SmartTrig AB  Detection unit and a method of using the same
WO2009019706A2 *2007-08-09  2009-02-12  Elta Systems Ltd  Method and apparatus for detecting pedestrians
US20100157729A1 *2008-12-19  2010-06-24  Bae Systems Information And Electronic Systems Integration Inc.  Seismic Method For Vehicle Detection And Vehicle Weight Classification
US20110199861A1 *2007-03-12  2011-08-18  Elta Systems Ltd.  Method and system for detecting motorized objects
US8331195B1 *2008-10-20  2012-12-11  Army  Computer implemented sensor data analysis
US20150168545A1 *2013-12-13  2015-06-18  Agency For Defense Development  Distance estimation device and method using the difference of wave speed between waves
US8331195B1 *2008-10-20  2012-12-11  Army  Computer implemented sensor data analysis - Igloo White (Wiki)
3995223 Seismic-acoustic detection device, George A. Gimber, Edward J. Cotilla, Salvatore R. Picard, Robert F. Starry, US Navy, Priority: 1970-02-19, Pub: 1976-11-3, 327/25; 367/93; 181/122 - "an acoustic sensor, a seismic sensor and an acoustic signal transmitter." Inventors are with Navy and have sonobuoy related patents.
Publication number  Priority date  Publication date  Assignee  Title
US3543172A *1968-09-19  1970-11-24  Anderson Jacobson Inc  Digital frequency discriminator
US3641443A *1969-12-11  1972-02-08  Westinghouse Electric Corp  Frequency compensated pulse time discriminator
US3705417A *1971-12-16   1972-12-05  Tel Tone Corp  Pulse ratio detector
Cited by
Publication number  Priority date  Publication date  Assignee  Title
US4107616A *1976-01-22  1978-08-15  M. L. Engineering (Plymouth) Limited  Signal monitoring circuit
US4230992A *1979-05-04 1980-10-28  Minnesota Mining And Manufacturing Company  Remote control system for traffic signal control system
FR2521307A1 *1982-02-11  1983-08-12  Krupp Gmbh  Passive method for acquiring data relating to a target that is a mobile preferably acoustic source
DE3306155A1 *1982-02-22  1983-09-01  Honeywell Inc  Device for weight-dependent classification of vehicles
FR2592200A1 *1985-12-24  1987-06-26  Maisonnette Miche  lElectronic device for detecting any untimely triggering of an alarm
US4811308A *1986-10-29  1989-03-07  Michel Howard E  Seismo-acoustic detection, identification, and tracking of stealth aircraft
US5007032A *1990-06-08  1991-04-09  Honeywell Inc.  Acoustic alert sensor
WO1991006874A1 *1989-11-02  1991-05-16  Rheinmetall Gmbh  Process for determining the direction and range of noise-generating targets
US5054006A *1970-02-19  1991-10-01  The United States Of America As Represented By The Secretary Of The Navy  Seismic-acoustic detection device
WO1997019368A1 *1995-11-17  1997-05-29  Stn Atlas Elektronik Gmbh  Method and device for detecting pedestrians
ES2170603A1 *1998-06-19  2002-08-01  Tzn Forschung & Entwicklung  Surface mine defense
US8331195B1 *2008-10-20  2012-12-11  Army  Computer implemented sensor data analysis
5054006 Seismic-acoustic detection device, George A. Gimber, Edward J. Cotilla, Salvatore R. Picard, Robert F. Starry, US Navy, App: 1970-02-19 (21 Year Delay) Pub: 1991-10-01, 367/136 -
Publication number  Priority date  Publication date  Assignee  Title
US2646559A *1949-06-09  1953-07-21  Nutzler Paul Gustav Adolf  Approach detection by high frequency radiation
US3094929A *1960-07-29  1963-06-25  Singer Inc H R B  Detonating system
US3125953A *1964-03-24  Amplifier
US3147467A *1961-09-07  1964-09-01  American District Telegraph Co  Vibration detection vault alarm system
US3375376A *1964-02-20  1968-03-26  Navy Usa  Anti-intruder device using vibration responsive member between light and photocell
US3474405A *1968-05-17  1969-10-21  Us Navy  Method and apparatus for detecting the presence of enemy personnel in subterranean chambers
US3543261A *1968-06-14  1970-11-24  Us Air Force  Upper threshold circuit
US3569923A *1967-10-30  1971-03-09  Us Navy  Adaptive acoustic detector apparatus
US3995223A *1970-02-19  1976-11-30  Navy  Seismic-acoustic detection device

Cited by
Publication number  Priority date  Publication date  Assignee  Title
US5373486A *1993-02-03  1994-12-13DOE Seismic event classification system
EP1835308A1 2006-03-16  2007-09-19  SmartTrig AB  Detection unit and a method of using the same
US8331195B1 *2008-10-20  2012-12-11  Army  Computer implemented sensor data analysis - Igloo White (Wiki)
US9851461B1 *2012-04-04  2017-12-26  Navy  Modular processing system for geo-acoustic sensing - Igloo White (Wiki)


Since the sonobuoy has a cylindrical ( 4-4/7" O.D.) shape it makes sense to have the electronics in the form of cylindrical modules that can be stacked end to end. These modules are about 2-3/4" O.D. and have a circular connector around the outer edge.  For use as an outdoor intrusion detector the hydrophone is replaced with a geophone (Wiki), or other sensor like used to listen for the RF generated from spark ignition engines. 

1st Generation

I think this outdoor intrusion sensor was made by modifying a sonobuoy.  The Automatic Radio Frequency Buoy (ARFBUOY) may be this unit or something very similar.
See Popular Mechanics March 1976 "War watch in the Sinai" references the "electronic battlefield" aka the "McNamara Line" (Wiki).   Mentions sensors:
See the web page:
and/or search on keywords: John T. Correll, Igloo White (Wiki), the McNamara Line (Wiki),
AF Magazine Nov 2004 -
Igloo White the quotes below are from this article.
The barrier would consist of a 20,000 air dropped listening devices combined with 240,000,000 Gravel mine and 300,000,000 Button mines and 19,200 Sadeye cluster bombs at a cost of around one billion dollars a year, not including 1.6 billion dollars for research and development, and the construction of a 600 million dollar command center in Thailand.

Spikebuoy - seismic sensor

"The Spikebuoy (66 inches long, 40 pounds) planted itself in the ground like a lawn dart.  Only the antenna, which looked like the stalks of weeds, was left showing above ground."
3995223 Seismic-acoustic detection device, George A. Gimber, Edward J. Cotilla, Salvatore R. Picard, Robert F. Starry, Secretary Of The Navy, Nov 30, 1976 (7 year delay), 327/25, 181/122, 367/93 -
5054006 Seismic-acoustic detection device, George A. Gimber, Edward J. Cotilla, Salvatore R. Picard, Robert F. Starry, Secretary Of The Navy, Oct 1, 1991 (21 year delay), 367/136 - 


(Air-Delivered Seismic Intrusion Detector) sensed earth motion to detect people and vehicles.  It resembled the Spikebuoy, except it was smaller and lighter (31 inches long, 25 pounds). It was the most widely used sensor in the program.

Acoubuoy - microphone

"The Acoubuoy (36 inches long, 26 pounds) floated down by camouflaged parachute and caught in the trees, where it hung to listen."

Arfbuoy - repeater

Photos courtesy of Dennis Starks

ARFBUOY Acoubuoy

This is an 18 pound steel cylinder 4-3/4"x22".
It's designed to be air dropped  with a drag chute and get hung up in the trees.  There is a central tape whip and four ground plane tape whips each 17" long.
which is a quarter wave at about 190 MHz.
outdoor intrustion
                  sensor was made by modifying a sonobuoy
outdoor intrustion
                  sensor was made by modifying a sonobuoy outdoor intrustion
                  sensor was made by modifying a sonobuoy
outdoor intrustion
                  sensor was made by modifying a sonobuoy outdoor intrustion
                  sensor was made by modifying a sonobuoy outdoor intrustion
                  sensor was made by modifying a sonobuoy
Automatic Radio Frequency Buoy (ARFBUOY)
The central gold colored thing is the microphone.  Note all the holes in the front to let sound in and protect the microphone from tree limbs.

Automatic Radio
                  Frequency Buoy (ARFBUOY)

Automatic Radio
                  Frequency Buoy (ARFBUOY)

Automatic Radio
                  Frequency Buoy (ARFBUOY)
Automatic Radio
                  Frequency Buoy (ARFBUOY) Battery

This is a battery type I don't recognize.  If you know about it please let me know what it is.
Sound Observer (Locator) Remote Microphone.
It's identical to the mike in the Acoubuoy.
Remote Sound
                  Obseerver (loation) Microphone
This is the same mike that's in the photo at left with
the question mark.  The 5 socket connector is marked:
7004 Deutsh
The contacts are numbered 1, 2, 3, 4 (but no 5).

There's a knurled and slotted screw head on the back that can be unscrewed about 1 turn, maybe to normalizing the pressure inside to match atmospheric.
See RT-1185 for a similar application.
Maybe one of the applications was to locate enemy small arms or big guns?

3704764 Air deliverable seismic system, Harold B Henderson, Texas Instruments Inc, Filed: 1969-12-23, Pub: 1972-12-05 - a motor rotates a cylinder until a pendulum is plumb, then feet extend and the antenna is raised.  Note TI and Vietnam time frame.  What is this? Let me know.  Has the feel of  "Metalhead" the dog robot in Black Mirror (YouTube).
Does not call other patents but is cited by:
5434828 Stabilizer for geophone, Roger M. Logan, Ion Geophysical Corp, 1995-07-18 - adds bumps so it will not roll around when on the bottom under water.
6531965 Modular open system architecture for unattended ground sensors, Stephen G. Kaiser, Mark D. Hischke, Shannon Mary Nelson, Stuart J. Collar, Dana Lynn Bourbonnais, Northrop Grumman Systems Corp, 2003-03-11 - the sensor modules look like those on the GSQ-154 & GSQ0160. "unattended ground sensor" (Wiki) mentioned many times.
History of the U.S. Army Research Laboratory - page with mention of UGS.
6823262 Method for conducting seismic surveys utilizing an aircraft deployed seismic source, Phillip Andrew Bahorich, Michael Stephen Bahorich, Apache Corp, 2004-11-23 - plane drops iron bomb w/o explosives, just it's weight hitting the ground makes the signal.
6831699 Deployable monitoring device having self-righting housing and associated method, Yu-Wen Chang, William Grainger, Michael Johnson, William Traeger, Pablo De Los Rios, William Osterholm, Chang Ind Inc, 2004-12-14  - egg shaped device with TV camera.
20060010998 Autonomous reconnaissance sonde, and method for deployment thereof, Roke Manor Research Ltd, 2008-05-20 - based on TV camera in Clay pigeon (Wiki).
WO2016139503 - sounds like a seismic sensor glues itself to the ground

Mines for Noise

The Turd, Gravel Mines (Wiki), and the BLU-43 Dragontooth (Wiki) were used as part of Operation Igloo White (Wiki).
More about land mines at Blasting Machines/M21 Training Land Mine -

USQ-42 Receiver

R-1617A/USQ-46 Receiver




When powered there is no indication on the front panel that the receiver is working.  Pressing the test buttons to the right of the display will light up each row of digits if the DIM control is clockwise.  If a handset is connected and the SQUELCH is turned down you can hear hissing in the speaker.


An eBay ad showed the GSQ-171 beside the USQ-46 receiver.  It has what appear to be Vietnamese markings.
What is this: Contact me


TS-2963 Test Set (Transmitter)

PP-6446A/USQ-46 Power Supply (Receiver, Test Set)

                  Power Supply
                  Power Supply

CS-12313/U for
                  PP-6446/USQ-46 or PP-6446/TS-2963

The following two units use "modular cylindrical building blocks).





1154272 Marine Mine, Emil Senger, Raimund Sauter, Sep 21, 1915, 102/408 -  a plug dissolves after a predetermined time scuttling the mine
1308003 Apparatus for detecting and indicating the presence of submarine boats, G.E. Elia (Italy), June 24, 1919, - raises a flag when sub entangles net
1426337 Signaling apparatus for detecting submarines, Sperry Elmer A, Filed: Jul 9, 1917, Pub: Aug 15, 1922, 455/97, 441/11, 343/709, 174/138.00R, 294/111, 313/553, 114/240.00R, 313/243, 102/402, 174/77.00R, 455/99, 174/153.00R, 343/896, 200/83.00R - when net is entangled by a sub the buoy sends a radio signal
2629083 Expendable radiosonic buoy, Barkson Joseph A, Mason Russell I, Mcnary James C, Filing: Sep 21, 1944, Pub: Feb 17, 1953, 367/3, 343/709, 455/99, 441/33, 441/23, 343/705, 343/901 -
Production of submarine signals and the location of submarine objects, Chilowsky Constantin, Langevin Paul, May 19, 1917 (W.W.I) Oct 23, 1923
                367/87, 367/174, 89/41.8, 89/41.7, 310/337 - uses the term "ultra-sonorous" 50 kHz to 200 kHz
Signaling apparatus for detecting submarines, Sperry Elmer A,  Jul 9, 1917, Aug 15, 1922, - triggered by net 455/97, 441/11, 343/709, 174/138.00R, 294/111, 313/553, 114/240.00R, 313/243, 102/402, 174/77.00R, 455/99, 174/153.00R, 343/896, 200/83.00R
2311079 Transducer, Jr Josephus O Parr, 1943-02-16, - seismometer
Method and apparatus for the detection of submarines by airplanes, Constantin Chilowsky, Apr 25, 1941, Oct 24, 1944, -
                 367/120, 102/419, 244/137.1, 367/130, 102/427, 434/6
                1829474 Method and device for establishing communication between aircraft in full flight and the ground, Chilowsky Constantin
2397844 Signaling apparatus, Wallace W DeWhurst (RCA) Apr 2, 1946, 367/3, 138/89, 114/198, 455/99, D10/107, 441/11, 73/322.5 - sonobuoy

2402391 Submarine detection, De Witt R Goddard, Rca Corp, Filed: Aug 30, 1943, Pub: Jun 18, 1946, 367/115, 124/51.1, 89/1.51, 367/112, 221/279 -

Submarine signaling apparatus, Robert E Peterson, Jan 23, 1943 (W.W.II) May 20, 1947, 114/23, 367/150, 114/21.1, 116/27, 181/402, 114/21.3 - uses the term "superaudible frequencies"  
2422337 Submarine Detecting Buoy, C. Chilowsky, Jun 17 1947, 367/4; 441/11; 441/25; 441/26; 441/28; 455/99 -
1249486 Sunken Ship Locating Device, Dec 11, 1917, 441/25; 242/156; 441/26 -
1195317 Observation-buoy and Fire Control for Floating Mines, Aug 22 1916,
1426337 Signaling Apparatus for Detecting Submarines, Aug 15 1922,
455/97; 102/402; 114/240.00R; 174/77.00R; 174/138.00R; 174/153.00R; 200/83.00R; 294/111; 313/243; 313/553; 343/709; 343/896; 441/11; 455/99 -
- sub hits net closing circuit keying a transmitter that uses a code wheel to identify it's serial number.
1427560 Means for Detecting Submarines, Aug 29, 1922, - another net type
1430162 Apparatus for Detecting and Indicating the Presence of Submaring Boats, Sep 26, 1922
1466284 Detecting System, (Western Electric) Aug 28, 1923, 367/122; 340/384.1 - multiple zone vibration detection
1610779 Signalling Apparatus, (GE) Dec 14 1926, -
1749444 Signal System, - police
2320610 Apparatus for Detecting and Indicating the Presence of Submarine Boats - net type

2438926 Magnetostrictive supersonic transducer, Mott Edward E, Bell Telephone Labs Inc, Apr 6, 1948, 367/168, 381/190, 335/215, 310/26
2417830 Compressional wave signaling device
Radio listening buoy, Hansell Clarence W, Rca Corp, Dec 2, 1944, Sep 7, 1948, 367/3, 343/709, 441/13, 455/99, 343/702
2465696 Method and Means for Surveying Geological Formations, LeCoy C Paslay, Mar 29 1949, 367/23; 114/245; 346/33.00C; 367/16; 367/20; 367/155 -
1378960 Method and Apparatus for Detecting Under Water Vibrations, J.W. Horton (WE), May 24 1921, 367/130 - submarine specific
1584613 Wave Detector, D.F. Comstock et al, May 11 1929, 367/130; 361/280; 361/283.1; 361/285; 367/129; 367/154 - sub detection directional array of sensors
2212988 Apparatus for Transmitting and Recording Shot Moments, D.K. Kirt (Gulf Oil R&D), Aug 27 1940, 367/77; 367/55 - seismograph prospecting
2241428 Apparatus for Underwater Seismic Surveying, D. Silverman (Standard Oil), May 1941,
2283200 Method and Apparatus for Subsurface Mining, J.W. Flode, 1942  - seismograph prospecting
2324378 submarine Prospecting, J.W. Flude, 1943 - seismograph prospecting
2440903 Underwater Transducer, F. Massa (Brush Dev Co), May 4 1948, 367/160; 381/163; 381/190 - piezoelectric or magnetostrictive transducers in towable rubber hose.

2511689 Submarine signaling apparatus, John T Beechlyn, Raytheon, 1950-06-13, - various designs of
magnetostriction using multiple elements

2521136 Hydrophone, A. Thuras, (USA) Sep 5, 1950, 310/26, 381/190, 367/168, 381/163

                        Automatically operated radio buoy, Freas Raymond
                        L, Apr 22, 1952
2593432 Automatically operated radio buoy, Freas Raymond L, Apr 22, 1952, 455/96, 455/99, 244/149, 455/91, 343/705, 455/98, 441/11, 455/97, 343/709, 367/4, 343/902

Falls straight down from aircraft over water.  Rights itself, an explosive extends the telescoping antenna, sends distress signal, after timer scuttles.

2629083 Expendable radiosonic buoy, Barkson Joseph A, Mason Russell I, Mcnary James C, Filed: Sep 21, 1944, Pub: Feb 17, 1953, 367/3, 343/709, 455/99, 441/33, 441/23, 343/705, 343/901 -

2641751 Hydrophone Casing, (Navy),  367/173, Jun 1953 -
806730 Device for locating and recovering sunken articles, Dec 5, 1905
1252877 Means for indicating the position of self-propelled vessels, Jan 8, 1918 - buoy released from practice torpedo at end of its run
1292755 Submarine detector or telltale, Jan 28, 1919 - net with alarm
1427560 Means for detecting submarine boats, Sperry Elmer A, Aug 29, 1922 - net with alarm
2261513 Mechanical boat lifter and indicator, Nov 4, 1941 -
2361177 Method and apparatus for the detection of submarines by airplanes, Oct 24, 1944 - fly in circle with long cable attached to hydrophone
2396960 Means for locating lost aircraft Mar 19, 1946 - 
2644243 Control Compass, (Navy), 361/280; 33/363.00Q, Jul 1953 -
1639000 Wave modulation, Western Electric Co, Aug 16, 1927 -
2036833 Tuning condenser arrangement
2116103 Compass for automatic pilots, May 3, 1938 -
2277027 Telemetric system, West Instr Co Inc, Mar 24, 1942 - servo compass repeater
2319212 Photoelectric control device, May 18, 1943 - used to read compass rose
2346839  Baking utensil?
2363500 Gyro magnetic compass system, Sperry Gyroscope Co Inc, Nov 28, 1944 - 
2749436 Sonobuoy, R.H. Rines et al, Jun 5 1956, 455/99; 342/6; 367/3; 455/91; 455/107; 455/116; 455/129 -
2063944 Means for Locating Crashed Airplanes, Jan 22, 1957, 116/210; 244/1.00R; 244/137.1 - based on sonobuoy technology
2063945 Diaphragm and Method
2063946 Sound Communication System
2063947 Compensator
2539594 System and Method of Communication
2361177 Method and Apparatus for the Detection of Submarines by Airplanes, C. Cilowsky, Oct 24 1944, - flying in circle lowers cable with hydrophone
2397844 Signaling Apparatus, W.W. Dewhurst (RCA), Apr 2, 1946, 367/3; 73/322.5; 114/198; 138/89; 441/11; 455/99; D10/107 - sub Tx buoy
2448713 Radio Listening Buoy, (RCA), Sep 7, 1948,  367/3; 343/702; 343/709; 441/13; 455/99 - very early sonobuoy
2448787 Apparatus for Detecting and Locating Enemy Vesels, (Ferrel Ind), Sep 7, 1948, - above surface microphone
2758203 Sonobuoy, Harris Wilbur T, Harris Transducer Corp, Aug 7, 1956, 455/99, 342/5, 367/4 - shock absorber in cable to reduce noise & hydrophone electronics in descending pod, not in floating part
2760180 Long range explosive sonobuoy, George Sipkin, Filed: Oct 6, 1949, Pub: Aug 21, 1956, 367/2, 102/390, 367/133, 367/127 - EER type Underwater Sound Source
2817909 Training Device for Operators of Underwater Detection Appratus, B.M. Taylor, et al, Dec 31 1957, 434/9; 434/10
1731127 Signal Control System (railroad), Oct 8 1929
1859423 Sound Recording - multiple needles for echos
2039405 Remote Metering System (AT&T) -
2066156 signaling Means, Apr 25 1929, - relative motion
2206156 Conveyer?
2206036 Distance Measuring Apparatus and System, J. Herson,  Jly 2 1940, - optical aircraft altitude blind landing
2329612 Apparatus for Training Aircraft Pilots, G.E. Hill et al, Sep 14 1943, - includes real time position output
2332523 Ground Track Tracer and Landing Recorder, E. Norden et al, Oct 26 1943, - servo controled pen recorders
2358793 Navigation Instruction Device, C.J. Crane, Sep 26 1944, - scaled movement of student over floor
2373560 Sound Recording Method and Apparatus, J.M. Hanert (Hammond Inst Co), Apr 10 1945 - adding vibrato
2375004 Training Apparatus, May 1 1945 - sound and recoil of a real gun
2444477 Automatic Miniature Radio Range (A-N), 1948 - used with pen recorder
2452038 Photoelectric Radio Compass Trainer Control, 1948 - based on scale map
2459150 Interception Trainer 1949 - call "Link" patents: 1825462, 2099857
2828475 Remote Control or Measurement Indicating Means, (Sec of Navy),  Mar 19 1958 - Sonobuoy that adds direction to sound in addition to just omni directional listening
1571006 Signaling system, Western Electric Co, Priority: Sep 8, 1920 (16 year delay) Pub: Jan 26, 1926 - motor based secret signaling
1592940 Secret signaling, Western Electric Co, Priority: Sep 9, 1920 (16 year delay) Pub: Jul 20, 1926 - motor based secret signaling
1718497 Telemetric system, Gen Electric, Jun 25, 1929 - servo remote indicating
1732741 Duplex radio transmission system, Westinghouse Electric & Mfg Co, Oct 22, 1929 - combined audio & coded signals from a single source
1913512 Meteorological indicator, Jun 13, 1933 - radio transmitter hung below tethered - early radiosonde
1928969 Well survey instrument, Union Oil Co, Oct 3, 1933 - probe in pipe sends attitude info to surface
2089987 Means for operating a repeating device, Pioneer Instr Co Inc, Aug 17, 1937 -
2103847 Signaling, RCA - HF radio multiplex, Dec 28, 1937
2151747 Receiving system, Westinghouse, Mar 28, 1939 - simultaneously receives AM and FM signals
2177493 Fire detecting apparatus, works by photocell seeing movement of light
2316317 Frequency-responsive network, Hazeltine, Apr 13, 1943 - FM receiver for narrow band modulation ( 1 kHz)
2334704 Automatic pilot, Nov 23, 1943, uses magnetic sensors to control frequency generator (very similar to how DIFAR encodes direction)
2357975 Frequency modulation system, Rca, Sep 12, 1944 - receiver suitable for both AM and FM reception
2361177 Method and apparatus for the detection of submarines by airplanes, Constantin Chilowsky, Oct 24, 1944 - see MAD patents
2448787 Apparatus for detecting and locating enemy vessels, Ferrel Ind, Sep 7, 1948 - rotating hydrophone and radio transmitter (DIFAR)
1610779 Signaling apparatus, Gen Electric, Dec 14, 1926 - an underwater device that sends a signal when it receives a signal.  aimed at ship positioning, but could also be used for sub detection?  A number of patents reference this on.
2838741 Underwater sound detection system, Warren P Mason, Bell Labs, 1958-06-10, - SOSUS (Wiki) idea started in 1949) this is the correct time frame.
for use on a continental shelf where there's constant depth where the low frequency cutoff  is given by f = v/4H.
If H = 1640 feet (500 meters) (Wiki: Blake Plateau) and v = 1500 meters/second; then
f = 1500/(4*500) = .75 per second or about 1 Hz.
This is very similar if not identical to waveguide propagation modes (Wiki).
Uses a shore station.
2432083 Hydrophone Jr Robert Black, Frank F Romanow, Oscar A Shann, Bell Labs, App: 1942-12-08, W.W.II, Pub: 1947-12-09, -
3022448 Modular sub-assembly, Feb 1962

3093808 Air-dropped miniature sonobuoy, Gimber George A, Scarcelli Albert F, Tatnall George J, Secretary of the Navy , Jun 11, 1963, 367/4, 441/33, 441/25, 343/709, 455/99 - Prior art sonobuoys were 3' long, 5" diameter and weighed 16 to 20 pounds limiting aircraft time on station and had a max depth of about 50'.  This one is 15" long, about 3" dia and weighs about 5 pounds with a max depth of 300'.
3116471 Radio sonobuoy system, Jesse J Coop, Dec 31, 1963, 367/3, 367/5, 367/113, 367/101, 367/126, 367/115, 318/638 -  In the present invention a multi-beam directional hydrophone is utilized in a radio sonobuoy system whereby an immediate quadrant location and an accurate distance measurement of a reflecting object from the multi-beam directional sonobuoy can be obtained from a single pressure pulse generated in the water area of interest.  - DIFAR
Radiosonic buoys, Guy Maes, Electronique Appliquee, Feb 9, 1959, May 5, 1964, 367/4, 340/870.28, 343/710, 441/23, 455/127.1, 455/99, 441/11, 340/870.1, 343/880
3140886 Coupling Device, E.J. Cotilla, George A. Gimber, Navy, July 14, 1964, - for separating the float from the hydrophone,
3213409 Condition selector apparatus, Paul C Bailey, George A Gimber, Navy, Aug 19, 1963, -
3262094 Discontinuous hollow cylindrical transducer, Leon W Camp, Bendix, 1966-07-19, - polarized magnetostriction transducer  7 to 10 kHz
3276049 Deep water buoyancy apparatus, Thomas E Stixrud, Navy, 1966-10-04, - "A more particular object of this invention is to provide a deep water buoy which utilizes the vaporization of a liquid gas as a source of buoyancy. "
3281765 Minature Sonobuoy and Cable (ITT), Oct 25, 1966 - small dia (0.030") cable which acts as a spring, Ni-Cad batt charged prior to use.
2641751 Hydrophne Casing, Bernier Jr Hector F, Mason Russell I, Ripken John F, Us Navy, Filed: May 11, 1944, Pub: Jun 9, 1953, 367/173 - about playing out the line supporting hte hydrophone below the buoy.
3093808 Air Dropped Miniature Sonobuoy, (Navy), Jun 11, 1963, 367/4; 343/709; 441/25; 441/33; 455/99 -
3290642 Directional Sonobuoy, (Navy), Dec 6, 1966,  367/4; 367/120; 367/129; 441/33 - weight driven rotating sensors
3309649 Sonobuoy with Depth Selection Capabilities, Sanders Assoc, Mar 14 1967, 367/4; 441/33 -
3328750 Entrapped air flotation device, George A Gimber, Roy L Shipman, Navy, June 27, 1967, - instead of using a CO2 cartridge

Compliant suspension system, Sparton Corp, Apr 9, 1968
3460058 Radio Sonobuoy, (ITT), Aug 5, 1969, 367/4 - operates below thermocline
3517378 Underwater long-distance sound-detection system, Barrett Robert E, Us Navy, Filed: Nov 6, 1959, (11 year dealy), Pub: Jun 23, 1970, 367/2, 367/134 - EER explosive
3526002 Magnebuoy, Ramond C Waddel, 1970-08-25, - Proton Precession (kerosene) (Wiki)
3671928 Automatically energizable Sonobuoy, Aquatronics, Jun 20 1972, 367/4; 441/11; 441/33 - some similarity to acoubuoy.
3720909 Directional Hydrophone System, Spartan Corp, Mar 13 1973, 367/173 - seismic sensors in sonobuoy
3451040 Spring Suspension for a Low-frequency Geophone, W.R. Johnson, )MarkProd Inc), Jun 17 1969, 367/183 -
2390328 Directional Seismograph Pickup, R.J. Roberts (Std Oil), Dec 4, 1945, 367/185; 340/870.35 -
2856594 Seismic Detector, K.W. McLoad (Vector Mfg), Oct 14 1958, 367/154; 73/652 - underwater
3325778 Seismic Sonobuoy, S.S. Ballard (Sanders Assoc), Jun 13, 1967, 367/21; 330/51; 330/124.00R; 330/278; 367/66; 455/99 -
3377615 April 1968 Lutes
3281765 October 1966 Taplin
2435587 February 1948 Harry
3372368 March 1968 Dale et al.
3539979 November 1970 Crall
3724374 Underwater sound source, Smith D, Somerville J, Yaccarino J, Us Navy, Apr 3, 1973, 181/116, 367/3, 367/145, 102/417 - used with sonobuoys, multiple charges triggered by radio from the aircraft
3786403 Underwater Acoustical Detection, Navy, Jan 1, 1974, 367/4; 441/25; 441/26 - (Search-In-DEpth Concept of Acoustic Ranging = SIDECAR),
app 549209 Apr 19 1966 A.S. Will et al
app 452460 Apr 18 1965 Urick et al
app 502713 Oct 22 1965 Urick
2422337 June 1947 Chilowsky
3222634 December 1965 Foster
3275976 September 1966 Farmer

3921120 Float Actuated Release Mechanism, Sparton Corp., Nov 18 1975, 367/4; 116/209; 441/33 -
2778332 January 1957 Talbot
3093808 June 1963 Tatnall et al.
3140886 July 1964 Cotilla et al.
3220028 November 1965 Maes
3309649 March 1967 Ballard et al.
3646505 February 1972 Kirby
3701175 October 1972 Widenhofer
3944964 Air Dripped Linear Acoustic Detector, (Navy), Mar 16, 1976,  367/4 -
3982222 Deep hydrophone string, Robert J. Urick, Navy, App:1965-10-22, Pub: 1976-09-21, - "...long range detection, surveillance and communication by means of sonobuoys operating in the deep sea and is more particularly concerned with a deep hydrophone string operatively connected with a specialized sonobuoy for this purpose. "
3991475 Depth selecting spool device, Navy, Nov 16, 1976, 116/209; 367/4; 441/24 -
3093808 June 1963 Tatnall et al.
3262090 July 1966 Farmer
3921120 November 1975 Widenhofer

4096598 Selected Depth Mooring System, R.J. Mason, 441/25, Jun 1978 -
3631550 Mooring Devices, (EMI), 441/25, Jan 4, 1972 -
4026188 Modular buoy system, Thomas E. Woodruff, Roger I. Saunders, Lockheed Sanders Inc, 1977-05-31 -

Patent Citations (11)

Publication number  Priority date  Publication date  Assignee  Title
US2913198A *1955-10-04  1959-11-17  Leona A Bonbrake  Sonobuoy dispenser
US3010396A *1957-12-31  1961-11-28  Western Co Of North America  Selective firing apparatus
US3095814A *1960-06-30  1963-07-02  Tor W Jansen  Dispensing apparatus
US3116689A *1959-07-07  1964-01-07  Halliburton Co  Well perforating apparatus and switch
US3142959A *1959-09-11  1964-08-04  Phillips Petroleum Co  Range control of self propelled missile
US3246707A *1964-02-17  1966-04-19  Schlumberger Well Surv Corp  Selective firing system
US3266372A *1964-08-27  1966-08-16  Harold J Mack  Shipping and launching container
US3368480A *1966-04-15  1968-02-13  Navy Usa  Folding cone sonobuoy delivery system
US3451306A *1967-01-26  1969-06-24  Susquehanna Corp  Safe and arm ejection system
US3768408A *1971-09-30  1973-10-30  Gearhart Owen Industries  Selective firing apparatus
US3787012A *1973-02-05  1974-01-22  Mc Donnell Douglas Corp  Internal ejector mechanism for stacked sequentially releasable separable
4092627 Calibration circuit for expendable sonobuoys, Donald Murdock, Thomas E. Stixrud, Navy, 1978-05-30, - a dual 555 timer (Wiki) circuit generates a signal that's applied to a 10 Ohm resistor between the hydrophone and ground to make a test signal.  15VDC supply, R5 & 10 Ohms.  17 minutes off and 1 minute one using a 10 Hz test signal.  The value of R5 is not mentioned so the amplitude of the signal in series with the hydrophone can only be guessed.  If R5 was 1 Meg then the current would be 15V/1M = 15 uA.  15 uA * 10 Ohm = 150 uV.
4114137 Directional Sonobuoy, (Navy), 367/171; 441/1; 441/28, Sep 12 1978
  768568 Sound transmitter and receiver, Submarine Signal Co, Aug 23, 1904 - stereo hydrophone with 2 long pole earphones
1345717 Acoustic device, Western Electric, Jul 6, 1920 - carbon button microphone mounted in a tear drop shape for use underwater.
3382481 Cantilever mounted hydrophone, Texas Instruments, May 7, 1968 - marine seismometer insensitive to cable strumming (5 Hz and above).
3803540 Inflatable underwater platform, Nat Defence, Apr 9, 1974 - water pumped into tubes to from a structure for sonobuoy (to make hydrophone array) many patents reference this one
3864771 Deployable load buoyancy support container or shelter system, Textron, Feb 11, 1975 - telescoping sonobuoy construction

4143349 Cable depth selector and coil shunt penetrator, (Bunker Ramo Corporation), Mar 6, 1979, 367/4, 441/1, 439/391 -
4161716 Very low frequency sonobuoy (VLF sonobuoy), Thomas E. Stixrud, Navy, 1979-07-17, -
4186370 Stabilized sonobuoy suspension, Raytheon, Jan 29, 1980, 367/4; 367/130; 441/11; 441/33 -
4189786 Radio Buoy Assembly, R.E. Adler, Feb 19 1980, 367/4; 367/5; 367/133 -
4246671 Buoy anchoring system, Richard C. Swenson, Navy, 1981-01-27, -
Sonobuoy system, Albert S. Will, Earl A. Schuchard, John P. Buckley, Armand Cioccio, John C. Hetzler, Jr., Sylvan Wolf, Donald E. Jefferson, Jim B. McQuitty, Robert A. Urick, Secretary Of The Navy, Apr 6, 1982 (16 year delay), 367/4, 367/173, 367/153 - A deep water explosive echo ranging system capable of detecting high perfance submarines by using favorable acoustic paths available at deep depths.

4357688 Low cost sonobuoy, Navy, Nov 2, 1982, 367/4; 367/173 -
4358834 Self-deploying Buoy System, Navy, Nov 9, 1982, 367/4; 367/173 -
4493664 Sonobuoy Float Inflation and Depth Selection Initiators, Navy, Jan 15, 1985,  441/7; 222/5; 367/4; 441/26; 441/30; 441/33 -
4530269 Remotely Initiated Speration Latch Assembly, Burroughs Corp, Jul 23 1985, 89/1.14; 102/293; 102/378; 220/261; 367/4; 367/173; 403/2 - electrical match for seperation
4590590 Sonobuoy Multiple Depth Deployment Apparatus, Magnavox, May 20 1986, 367/4; 441/25; 441/33 -
4727520 Cable Deployment Unit, Sparton of Canada, Feb 23, 1988, 367/4; 367/3; 441/25 -
4901288 Compact cylindrical sonobuoy, Sparton Corp, Feb 13 1990, 367/4 -
4924445 Sonobuoy Cable Pack, Royal Navy, May 8, 1990, 367/4; 114/326; 367/3; 441/8 -
4927057 Automatic Infiltrator for Inflatable Articles, Inflation Tech, May 22, 1990, 222/5; 222/23; 222/41; 222/52; 222/63; 222/93; 222/94; 441/93 -
4493664 Sonobuoy float inflation and depth selection initiators, John R. Dale, Secretary Of The Navy, Jan 15, 1985, 441/7, 441/26, 222/5, 441/30, 367/4, 441/33 -
4560228 Electrical connector for sonobuoy launch system, Roland Bender, Navy, Dec 24, 1985, - pogo pins and metal contacts
5076468 Squib Inflator Adapter, Halkey-Roberts Corp, Dec 31, 1991, 222/5; 222/91; 441/93 -
5197036 Sonar Array Mounting for Sonobuoy, Mar 23, 1993, 367/4; 367/153 -
5426617 Long baseline tracking system, Reginald J. Cyr, Secretary Of The Navy, Jun 20, 1995, 367/6 - uses multiple underwater transponders
6400645 Sonobuoy Apparatus, (Navy), Jun 4, 2002, 367/4; 367/3; 367/153 - opens sort of like an 8-sided umbrella


3603921 Sound transducer, Robert H Dreisbach, Magnavox Electronic Systems, 1971-09-07, - 4 lobe hydrophone for sonobuoy
3656151 Digital function generation network, William E Richeson Jr, Mike B Feher (N4FS), Magnavox, 1972-04-11, 341/147; 341/153 -
"In the early days of DIFAR there was no real grayscale on the chart paper which indicated signal strength. Essentially you either had nothing or a real dark line. My logarithmic converter remedied that in that it allowed smooth transitions as signal strength varied. Of course now there would be so many better ways of doing it. However, at the time it worked and everyone was pleased. 73 – Mike"  See AQA-7 below.
4007316 Deferred action battery having an improved depolarizer, Ralph F. Koontz, Magnavox Co, 1977-02-08, 429/118; 429/220; 429/229 -
4192913 Deferred action battery having an improved depolarizer, Ralph F. Koontz, Lloyd E. Klein, Magnavox Electronic Systems, 1980-03-11, 429/119; 429/220
4261853 Deferred action battery having an improved depolarizer, Ralph F. Koontz, Lloyd E. Klein, Magnavox Govt & Ind, 1981-04-14, 252/182.1; 429/118; 429/119; 429/220 -
4268912 Directional hydrophone suitable for flush mounting, John C. Congdon, Magnavox, 1981-05-19, 367/163; 310/337; 310/365; 310/366; 367/164; 367/174 - for use on submarine
4494024 One shot spring activated motor, Gerald W. Braun, Magnavox Govt & Ind, 1985-01-15, 310/75A; 200/61.08; 310/273 - a squib (resistor) severs a cord releasing a CW or CCW spring to drive a shaft (for setting depth of hydrophone).  Note some torpedo gyroscopes use a very similar squib released spring motor.
4546459 Method and apparatus for a phased array transducer, John C. Congdon, Magnavox, 1985-10-08, 367/155; 367/157; 367/159; 367/165 - DIFAR beam forming
4590590 Sonobuoy multiple depth deployment apparatus, James R. Toone, Robert L. Barker, Magnavox, 1983-11-29, 367/4; 441/25; 441/33 - See Fig: 53-21, 53-23, 53-24,
4611293 Method and apparatus for automatic calibration of magnetic compass, Ronald R. Hatch, Richard G. Keegan, Magnavox Electronic Systems, 1986-09-09, 702/92; 324/245; 33/355R; 33/356 - 360 deg turn compensates for both soft and hard iron. 3-phase Earth Induction compass (aircraft application?)  [Hatch holds many GPS related patents)]
4654832 Sonobuoy retaining and release apparatus, Robert L. Barker, Magnavox, 1983-11-29, 367/4; 441/33 - Sonobuoy parachute, see figs: 53-6, 53-7, 53-8
4660040 Target range sensing apparatus, Norman Grandos, Magnavox Govt & Ind, 1987-04-21, 342/128; 342/193; 342/68 - "Target range sensing apparatus" - maybe a bomb fuze using FM-CW, or a sonobuoy range detector?
4689773 Extendible sonobuoy apparatus, John C. Congdon, Thomas A. Richter, Joseph J. Slachta, Magnavox, 1982-12-02, 367/3; 367/159; 367/165; 367/169; 367/173 - DIFAR sonobuoy
4700100 Flexural disk resonant cavity transducer, John C. Congdon, Thomas A. Whitmore, Magnavox, 1987-10-13, 310/332; 310/324; 310/326; 310/337; 367/155 - improves the frequency response of Helmholtz cavity in the 1 to 2 kHz range.
4709359 End weighted reed sound transducer, Rayford A. Loftin, Magnavox Govt & Ind, 1987-11-24, 367/155; 367/161 - four vanes
4797841 Method and apparatus for automatic calibration of magnetic compass, Ronald R. Hatch, Magnavox Govt & Ind, 1989-01-10, 702/92; 324/245; 33/355R; 33/356 - 3-phase Induction compass
4777627 Extendible sonobuoy apparatus, John C. Congdon, Magnavox, 1985-06-26, 367/3; 367/159; 367/173; 367/4; 441/1 -
EP0098017A2 End weighted reed sound transducer, Rayford A. Loftin, Magnavox Electronic Systems, 1985-08-28, - four bars
4970703 Switched capacitor waveform processing circuit, Peruvamba R. Hariharan, Robert W. Downing, Magnavox Govt & Ind, 1990-11-13, 367/138; 367/122 - sonar beam forming or sonobuoy?
5018116 Inter-element mounting for stacked piezoelectric transducers, John C. Congdon, Magnavox Govt & Ind, 1991-05-21, 367/165; 310/334 -
5046031 Method and apparatus for automatic flux-gate compass calibration, Richard E. Wanous, Magnavox Govt & Ind, 1991-09-03, 702/92; 33/356; 324/245; 73/1.76 - compensates for loading & unloading the vehicle (not sonobuoy, but shows a lot of understanding in fluxgate magnetometers as used on DIFAR sonobuoy).
5073136 Collapsible sonobuoy flotation device, Paul H. DeWitt, James J. Majewski, Thomas A. Richter, Magnavox Electronic Systems, 1990-03-29, 441/7; 441/11; 441/21; 441/30; 441/32 - Pagoda/ Accordion shape can be pressed flat for stowage.  


3613069 Sonar system, Cary Boyd B Jr, Fenlon Francis H, Gen Dynamics Corp, Oct 12, 1971, 367/92, 367/104, 367/107, 367/101 - combines two Tx frequencies (Mixer Transducer & Pump Transducer- higher SPL), 12, 48 & 60 kHz.    
4194246 Noisemaker beacon, Ralph P. Crist, US Navy, 1958-05-12, -
Saturation limited parametric sonar source, John M. Huckabay, Reuben H. Wallace, Secretary Of The Navy, Mar 16, 1982, 367/138, 367/92 - phased array?  
4777627 Extendible sonobuoy apparatus, John C. Congdon, Magnavox, 1988-10-11, - DIFAR

Barrier sonar, Francis J. Murphree, Secretary Of Navy, Filed: Jul 19, 1968(12 year delay) Pub: Jul 3, 1990, 367/138, 367/87, 367/93 -
4998224 System for providing improved reverberation limited sonar performance, Mar 5, 1991
5138587 Harbor Approach- Defense Embedded System, (Navy), 367/136, Aug 1992
5144487 Expendable moving echo radiator, (Navy),  367/1; 367/137; 367/165, Sep 1992 - countermeasures equip
5235558 Choke point bistatic sonar, Harvey C. Woodsum, Joseph J. Stapleton, Gte Government Systems Corp, Aug 10, 1993, 367/92, 367/104, 367/15, 367/908 -
5808580 Radar/sonar system concept for extended range-doppler coverage,
6018493 Sonar Suspension Apparatus, Dowty Maritime Sys, Jan 25, 2000,  367/16; 367/20; 367/153; 367/155; 367/165; 441/33 -

Dr. Breed & Hughes

5134369 Three axis magnetometer sensor field alignment and registration, Allen K. Lo, Wilbur W. Eaton, Jr.Ben R. Breed, Raytheon (Hughes), 1992-07-28, -
5239474 Dipole moment detection and localization, Wilbur W. Eaton, Jr.Ben R. Breed, Raytheon (Hughes), 1993-08-24, - based on Anderson Localization (Wiki
5617099 Adaptive filtering of matched-filter data, Ronald W. Warren, Ben R. Breed, Raytheon (Hughes), 1997-04-01, -


Photo from Wiki Sonobuoy page

From Ships and Aircraft of the U.S. Fleet (2005):
The P3C Orion. . .  tail-mounted ASQ-81 Magnetic Anomaly Detector (MAD) and 48 external (fuselage) sonolbuoy chutes and four in-flight reloadable (internal) chutes; a total of 84 buoys normally are carried.
P#C Orion External Sonobuoys being installed

Note The silver cylinder on the top of each sonobuoy.
It's a gas generator that's electrically triggered.
Cartridge-Actuated Device = CAD
An alternative to using compressed gas from a tank.
See patents directly below.
Fig 1 from patent 3905291:

                  Cartridge-Actuated Device and Launching Assembly using
                  same, G.T. Corbin, Sep 16 1975, 102/430; 42/96

2707904 Sonobuoy Dispensers, Breeze Corp, May 10, 1955, 89/1.51; 367/3 - revolver,
3093808 Air-dropped miniature sonobuoy, George J Tatnall, Albert F Scarcelli, George A Gimber, US Navy, 1963-06-11, -
3266372 Shipping and launching container, Harold J Mack, Albert F Scarcelli, US Navy, 1966-08-16
3451306 Safe and Arm Ejection System, Susquehanna Corp, Jun 24 1969, 89/1.1; 89/1.51; 102/259; 102/357 -
3905291 Cartridge-Actuated Device and Launching Assembly using same, G.T. Corbin, Sep 16 1975, 102/430; 42/96 -
4026188 Modular Buoy System, Sandars Assoc, May 31 1977, 89/1.51; 102/351; 102/352; 102/354; 102/406 -
4263835 Sonobuoy Launcher System, Navy, Apr 28, 1981, 89/1.51; 89/1.3; 89/1.806; 89/1.818 - bouys loaded from outside
4397433 Revolving-cylinder jettison device for transporting and releasing buoys on and from Aircraft, , Aug 9 1983, 244/137.4; 89/1.51; 89/1.801; 244/118.1 -
5052270 Multi-sonobuoy launch container with constant force spring, Navy, Oct 1 1991, 89/1.51; 244/137.4 -
7278416 Pneumatic projectile launcher and sonobuoy launcher adaptor, Lockheed-Martin, Oct 9, 2007, 124/72; 89/1.51 -

Magnetic Anomaly Detector (MAD) (Wiki)

The Earth's magnetic field varies between 25,000 and 70,000 Gamma (aka: nanoTesla) (Wiki) depending on the location.
These were originally called Magnetic Airborne Detectors (Ref 3) and was developed by the NDRC (Wiki) and was paired with the use of sonobuoys.

Maximum range 1 to 2 thousand feet. I'm guessing the range includes the depth of the sub, so the deeper the sub the more likely MAD will miss it.

When I lived in Mountain View it was a very common sight to see a P-3 Orion (Wiki) landing or taking off from Moffett Field Naval Air Station (Wiki).  They had a "stinger" on the tail that held the magnetic anomaly detector.  Here's a Youtube video of the MX-1361/ASQ-8 MAD
It appears to have 3 coils, each about 4" in diameter by 2" thick made by TI mounted in 3 orthogonal directions (X, Y & Z)

The ASA-65 is the motion compensator for the ASQ-81 MAD system.  That's to say that any motion of the P-3 will cause the X, Y & Z components of the Earth's magnetic filed to change.  To back that out three coils can be placed over the magnetic sensors and those coils driven from the output of the ASA-65.

When testing a MAD a small portable "Gamma Slinger" is used that generates a known (1045' c.g.s units) rotating magnetic field.

1045 Gauss converts to 104,500,000 nanotesla.  Since the Earth's field is about 50,000 nanotesla the Gamma Slinger is about 2000 times as strong as the Earth's filed.
It's probably made using a modern permanent magnet rotated on a shaft by a clock work where the shaft and clockwork are all non magnetic.  This test device could be used on the flight line to check out the MAD system.

It can easily be detected at over 20 feet using the ASQ-81.

The AN/ASQ-208 is a digital processing type MAD system.

The ASQ-1, ASQ-1A, ASQ-3 and ASQ-3A  was used in conjunction with the CRT-1 sonobuoy in W.W.II.
Ref pg 302, Chapter 16, SOFAR, Harbor Defense, and other SONAR Systems, Naval Sonar, NAVPERS 10884, 1953

The ASQ-3A was used as the basis of an magnetic survey of the world.
Ref: Airborne Geomagnetic Surveys by the United States Hydrographic Office, Henry P. Stockard, USN Hydrographic Office, NAVIGATION, Journal of The Institute of Navigation, Vol. 4, No. 8, 1955, pp. 320-323. modified to use the Vector Airborne Magnetometer type 2A (VAM-2A)

NOL vector airborne magnetometer type 2A (VAM-2A)

The Pave Mace system that used the Black Crow MAD sensor was optimized to pickup the magnetic filed from ignition system in Vietnamese vehicles.  (link to external web page with photo of it).  The plate to the side of the dome with 3 rows of holes along the top and 3 more rows of holes on the bottom has the feel of a slot antenna for VHF or UHF signals, so more of a radio system than a MAD system.  If you have any definitive information let me know.
It's not clear if this is a magnetic system or a VHF/UHF radio system.
Jerry Proc: AN/ASQ-81 Magnetic Anomaly Detector - helium magnetometer


The system weighs 150 pounds, occupies 7,700 Cu. In., is made up of 6 boxes, uses 44 vacuum tubes and requires 700 Watts of power (115VAC 400~ 3phase & 28VDC).  The ASQ-10 weighs 32 lbs., has a volume of 1,200 Cu. In., uses 16 Vacuum tubes and needs only 117 Watts of power. (from NAVPERS 10317-A)

MX-1361 Three Channel (X, Y, Z) Magnetic Sensor

YouTube: Magnetic anomaly detector - 3 orthogonal coils made by Texas Instruments p/n: 29604 - This is not the anomaly detector but rather the aircraft magnetic orientation sensor used to drive the X-Y movement of the DT-37 magnetometer.  See References below.

C820 Control Panel

Label on back:  C-820/ASQ-8, NOas 53-340, 439:CGO
Sticker on front panel: RCAF Inspection Due 0439?, 23/68, 7690-21-801-0255, RCAF S69
Labels above grommets: P1301 and P1302 and the cables have been cut off.
Changes 05 and 06 are scratched.

Side panel label: RCAF Instection Due, Batteries Installed 7 Dec 67, 7690-21-801-0255, RCAF S69.

There were internal batteries.  What voltages?

Fig 1 Front
ASQ-8 MAD C820
                    Control Panel
Fig 2 Back
ASQ-8 MAD C820
                    Control Panel
Fig 3 Inside top to right.
ASQ-8 MAD C820
                    Control Panel
Fig 4 Inside Maybe precision wire wound resistors at right side.
ASQ-8 MAD C820
                    Control Panel

17H-4 Gamma Slinger

Wiring:  A & B = AC input (Voltage TBD), C= ground.

Fig 1
ASQ-8-17H-4 Gamma Slinger
Fig 2  North pole near nut.
ASQ-8-17H-4 Gamma Slinger
Fig 3 Motor: Hurst, Princeton, M.D.
about 60mm diameter
ASQ-8-17H-4 Gamma Slinger


Aviation Electronics Technician 3 & 2, Bureau of Naval Personnel, Navy Training Course, NAVPERS 10317-A,
Ch. 14 Magnetic airborne detection equipment.
Ch. 15 Airborne Sonar and Sonobuoys. - SSQ-2B sonobuoy contains an X-band or S-Band RADAR beacon receiver that effects the output frequency in the 162 to 174 Mc range.  This  is used as an aid in locating the sonobuoy.  I'm guessing to make them show up on the search RADAR is bright dots.
The data on the ASQ-10 in the below table is my best guess based on comments in NAVPERS 10317-A (page 401).

ASQ-8 System
                    diagram from NAVPERS 10317-A
System Components
AM-294 Electronic Control Amplifier
PP-447 Power Supply
Driver Magnetometer
CN-19 Magnetic Compensator
AM-295 Amplifier Detector
Detecting Head (stinger)


Switch Box

Detecting Set Control

Coil Assembly

TR-218 The Influence of the Natural Enviornment on MAD Operations 1969 - The ASQ-10 will be followed by the ASQ-81 on the P-3 Orion.  The ASQ-81 uses an optical pump type magnetometer (Wiki) rather than the flux-gate type magnetometer used on the ASQ-8 and ASQ-10.
YouTube - Andrew Ochadlick: Optically Pumped Magnetometer Sensitivity and Helium-4 Energy Levels 2015 - Part1 (theory), Part 2 (ASQ-81 details), Part 3 (Uncertainty Principal) - very technical/physics. - Google Search "Princeton Lorentz Violation"

Magnetic Anomaly Detector (MAD) Patents

2361177 Method and apparatus for the detection of submarines by airplanes. Constantin Chilowsky, Filed: 25 Apr 1941, Pub :24 Oct 1944, 367/120, 102/419, 244/137.1, 367/130, 102/427, 434/6 - Referenced by 35 patents - not MAD but rather audio

2406870 Apparatus for responding to magnetic
                  fields, Vacquier Victor V, Gulf Research Development
                  Co, filed: Jul 21, 1941, Pub: Sep 3, 1946
2406870 Apparatus for responding to magnetic fields, Vacquier Victor VGulf Research Development Co, filed: Jul 21, 1941, Pub: Sep 3, 1946, 324/253, 102/417, 33/361, 318/647, 324/326, 324/345, 324/255, 340/870.33, 102/427
This is THE MAD patent and is referenced by a very large number of others.

The following detectors are towed on a cable from a plane flying at 300 feet above the water:
2379447 Antisubmarine device, Lindsey Henry A D, Jul 3, 1945, 102/417, 102/212, 340/551, 324/247, 324/67, 307/652, 324/258, 340/552
2404806 Submarine detector, Lindsey Henry A D, Jul 30, 1946, 340/850, 102/402, 324/247, 324/331
2424772 System for detecting magnetic masses, Frank Rieber, Interval Instr Inc, Jul 29, 1947, 324/247, 324/331, 322/1, 324/257, 322/59, 340/870.32
2485847 Combination magnetometer and gradiometer, Otto H Schmitt, Navy, App: 1944-09-23, (Secret?), Pub: 1949-10-25,
324/244; 340/870.33; 324/255 - two sensors in each wingtip, sum and difference outputs.
Cites 6 including:
2238072 Method and means for locating concealed bodies, Dale H Nelson, William D Buckingham,
Western Union Telegraph Co, 1941-04-15, 324/67; 102/406; 324/326; 324/243; 324/345; 405/173 - "...for locating and determining the depth to which a cable, or other body capable of afiecting, distorting and/or producing magnetic lines of force, is buried in the ground or otherwise concealed, and more particularly to locating and determining the depth to which submarine cables and the like are buried in the bed of the ocean or other body of water."
2549857 Cable-suspended aerodynamic body, Schonstedt Erick O, Apr 24, 1951, 324/260, 324/262, 114/24, 244/3, 74/5.00R, 324/331, 324/246, 33/397, 33/366.11
2555209 Method and apparatus for measuring the values of magnetic fields, Gary Muffly, Vacquier Victor V, Gulf Research Development Co, Filed: Nov 1, 1943, Pub: May 29, 1951, 324/246, 324/345, 324/253, - aligns MAD sensors with Earth's magnetic filed
2632884 Orienting mechanism for magnetic detector devices, Murphy Paul M, Mar 24, 1953, 324/253, 318/647, 324/246, 324/331
2696602 Compensated magnetometer, Richard Evans Chauncey, Dec 7, 1954, 324/253, 324/345 - uses term "magnetic anomalies"
3258687 Wide range linear fluxgate magnetometer, J.P. Heppner & H.R. Boroson, NASA, Jun 28 1966, - range 1 gamma to 10E-5 Gauss. 
3644825 Magnetic detection system for detecting movement of an object utilizing signals derived from two orthogonal pickup coils, Paul D Davis Jr, Thomas E Mccullough, Texas Instruments Inc, 1972-02-22 -
Cited by 133 patents.  - two coils allows determining direction of movement, like trucks along road - Outdoor Intrusion Detectors

SONAR Countermeasures

You see this in movies like The Hunt for Red October or Crimson Tide.
3771115 Simulated submarine target apparatus, McLinden Hugh   - a viscous, gelatinous  material having metalic particles suspended in it, is ejected by the sub to form a hollow bag-like structure which is filled with water.
2901997 Sound generator, Arthur H Brooks, Sep 1, 1959 (14 year delay), 116/27, 116/137.00R, 102/418, 367/1 -  
3194207 Underwater sound sources, Dunne Brian B, Gen Dynamics Corp, Jul 13, 1965, 116/27, 367/142 - alectric motor driven noise maker + flotation device, cylindrical shape (torpedo tube or smaller?) 
3612211 Method of producing locally occurring infrasound, William T Clark, 1971-10-12, - maybe similar to the Holosonics (Wiki) system that uses ultrasonics to generate an audio sound.
3786405 System for low-frequency transmission of radiant energy, M Chramiec, W Konrad, Raytheon, 1974-01-15, - underwater sound generation
3872421 Standing wave acoustic parametric source, Peter H Rogers, Buren Arnie Lee Van, Navy, 1975-03-18, -
underwater sound generation
3964013 Cavitating parametric underwater acoustic source, William L. Konrad, Navy, 1976-06-15, - bubbles provide for non-linear mixing
Noisemaker beacon, Ralph P. Crist, Secretary Of The Navy, Mar 18, 1980 (32 years delay), 367/1, 441/22, 441/12 - 10 to 100 kHz output
5117731 Tactical acoustic decoy, Mark A. Mendenhall, Secretary Of The Navy, Jun 2, 1992, 89/1.816, 102/348, 367/1, 102/501 - mounts on ship and jamms infrared, sonar & microwave.
6252822 Countermeasure device with air bag hover system and pressure compensated acoustic projectors, Robert J. ObaraSecretary Of The Navy, Jun 26, 2001, 367/1 - uses compressed air for both depth control and noise making   

Maybe called sonar counter counter measures was a type of sonar that was difficult for an enemy to hear.


A hydrophone (Wiki) is an underwater sound sensor.  On purpose I did not call it some type of microphone because that would imply it can only respond to sound within the frequency band which human ears can hear.  So, I think, sensor (Wiki) or transducer (Wiki) are better terms to use.  The key reason for that is most SONAR (Wiki) involves ultrasonic frequencies.

An early piezo electric material used for  hydrophones was Rochelle Salt (Wiki) which can be made from ingredients from the grocery store using instructions from YouTube.  Since it's water based, getting water on the crystal will dissolve it, so maybe not idea for an underwater application. Barium Titanate (Wiki) is another piezoelectric (Wiki) material used for hydrophones.  Although know in the W.W.II time frame, Titanium was not readily available in war time, so Magnetostriction (Wiki) was used for hydrophones early in W.W.II, like used on the CRT-1 sonobuoy.
See my Magnetics web page for an example of Terfenol-D material.

Got this hydrophone from Fair Radio.  It consists of a bladder just under five feet long and about three inches in diameter filled with mineral oil (or something similar).  Inside there are eight cylindrical  Rochelle Salt Crystal doublets, each about three inches long with about a three inch gap between sensors (series or parallel connection?). 

In the Combat Information Center magazine for July 1944 (Vol. 1 No. 5) there's an article on harbor defense that mentions both a sonobuoy with vertical hydrophone array (radio has 12 mile range and hydrophone has 1,000 yard range) as well as multiple hydrophones laid on the bottom and connected to multi-conductor cable.

At the cable end of the hydrophone is a matching transformer with 25 Ohm output impedance.  Frequency response of 1Hz to 20 kHz (i.e. young human hearing range).
The internal construction seems to be steel cylinders spot welded to two steel rods that tie them toghther.  The crystals are glued into the cylinders and wired in parallel.
If buried in the ground as is the mineral oil will leak out leaving air voids.  If repackaged in a PVC pipe the sound would travel up and down the pipe wall which doesn't happen with the current rubber bladder.  So maybe some type of flexable hose would be a good replacement? 

The idea is to bury it and have excellent low frequency (below 20 Hz) response.  The Infra sound sensors use garden hose with a pin hole leak.

Official Description:
Hydrophone, U. S. Navy Harbor Detection, Sonic, NT-51038F; P/O type JR-1 Harbor Detection Equipment.

Sensitive listening, frequency range 1 - 20 thousand cycles per second; with 8 Rochelle Salt Crystal Doublets each approx. 3" x 2" x 1", in metal frame w/matching transformer to 25 ohm line, in Castor (?) Oil, encased by heavy rubber jacket 56" long x 2 1/2" in diameter; with 9 foot rubber covered cable 1/2" O.D. w/2 flexible copper wires insulated, plus 2 steel strain wires; to be used down to 400ft. depth while withstanding high pressure explosion waves.  Mfg by Brush Development Company.
How can the transformer work over that frequency range? 

3 Feb 2012 - When the 999 average spectrum plot finishes I'll have a look at the impedance.

Fig HP1
Hydrophone, U.
                  S. Navy Harbor Detection, Sonic, NT-51038F; P/O type
                  JR-1 Harbor Detection Equipment.
Fig HP2 Transformer
                  U. S. Navy Harbor Detection, Sonic, NT-51038F; P/O
                  type JR-1 Harbor Detection Equipment - Transformer

Case Ground
White  -

 Opn  Opn  Sht



The Red and Blue terminals are physically in line.
The Black and Green terminals are physically in line.
The White wire is not an electrical connection but rather is where a couple of steel cables attach for supporting the weight of the hydrophone.
It's not clear what this is.
HP 4395A Plot 1 Hz to 20 kHz RBW: 1 Hz, True RMS detection, 16 averages:
8 Crystal
                Hydrophone spectrum 1 Hz to 20 kHz into 50 Ohm HP 4395A
HP 4395A Plot 1Hz to 20 kHz RBW: 1 Hz, True RMS detection, 999 averages (54.6 hours):
HP 4395A
                Plot 0 to 20 kHz RBW: 1 Hz, True RMS detection, 999
                averages (54.6 hours)
HP 4395A Z transform Impedance Real & Imaginary
HP 4395A Z
                transform Hydrophone Impedance Real & Imaginary
HP 4395A Z transform Hydrophone Impedance Smith Chart with Marker List
HP 4395A Z
                transform Hydrophone Impedance Smith Chart with Marker

2616223 Device for converting electrical energy into mechanical oscillation energy, Jonker Gerard Heinrich, 1952-11-04, - cited by 23 patents.
Tubular hydrophone, A.L. Thuras (New London, CT),  Sec of Navy, Mar 10, 1953, 367/168 -  CRT-1 
Helical magnetostrictive core line hydrophone, David E. Parker, Markay Malootian, Secretary Of The Navy, Oct 23, 1990 (21 year delay), 367/168 -   

Brush Development Co. Patents

Their early work with Piezoelectric devices (Wiki) was for microphones and speakers used in air.

1906758 Crystal and method of producing the same, Kjellgren Bengt, Brush Dev Co, May 2, 1933, 117/69, 117/68, 117/926, 252/1, 562/580 - Rochelle salt - but the methods seem the same as used today for silicon or any other crystal.
2105010 Piezoelectric device, Baldwin Sawyer Charles, Brush Dev Co, Jan 11, 1938, 381/190, 310/331, 367/164, 601/2, 367/161, 381/173 - Rochelle salt disk or plate or stacks or grids of them, mike or speaker
2126437 Apparatus for generating electrical waves - tubes
2269403 Piezoelectric unit - loudspeaker for use in air (for similar loudspeaker see: LS-685/U Crystal Loudspeaker)
2413462 Transducer, Massa Frank, Brush Dev Co, Filed: Jul 30, 1942, Pub: Dec 31, 1946, 367/157, 310/340, 381/190, 310/337, 310/362, 367/163 - early hydrophone (no projector function)  
2440903 Underwater transducer, Massa Frank, Brush Dev Co, Filed: Jan 6, 1944, Pub: May 4, 1948, 367/160, 381/190, 381/163 - "piezoelectric and magnetostrictive transducer devices adapted to function underwater either as a microphone or as a loudspeaker."  38 patents reference this one     


The geophones used in Vietnam era outdoor intrusion detectors are functionally seismometersHydrophones with good low frequency response can also be used as seismometers.  The MERMAID (Mobile Earthquake Recording in Marine Areas by Independent Divers - Earth Scope Oceans) devices drift at a depth of about 1500 feet to a mile and when they "hear" a P-wave (Wiki) they surface, get GPS coordinates and use the Iridium satellite telephone system to phone in the event.  The hydrophone output has a 0.1 Hz high pass filter and is sampled at a 40 Hz rate.  Note P-waves are very useful for studying the interior structure of the Earth.  They are the first (Primary) wave from an earthquake to reach a given location and so are the basis of earthquake alarms (Seismometer)

Son-Of-MERMAID (A tale about MERMAIDs) is also an ocean hydrophone that works more like a sonobuoy.  That's to say there's a float with GPS that knows where it is and a 1,000 meter cable supports a hydrophone.  An on board recorder captures events that appear to be P-wave events.

Note that this system does not detect S-waves (Wiki) and so is lacking a lot of earthquake data, but it is a way to get some data that covers 3/4 of the Earth (i.e. the oceans where there is currently no data at all on earthquakes). 

Hazeltine Hydrophone and Retainer Assembly A22267-1

Found this on eBay but the photos and description were not at all clear.  It's a linear array of 6 hydrophones.

Let me know if  you have any information on this hydrophone assembly.

Box label (Fig 1):
Hydrophone and Retainer Assembly
1 ea.
NOAS 58-548C
Hazeltine Corp Mfg/Contr
Sub-Item 5
Sensitivity Minus _____ db
(6 ELement Small Hydrophone HYDrophone?)

Cable can: 4" dia x 5-3/8" high
This is smaller than an A Size sonobuoy (4-7/8").
Maybe fits inside an A-Size?

Hydro Cup: 2" OD x 5" high
Cup holds 5 hydrophones + cup-end hydrophone
for 6 total.

Fig 1 OEM Box
Hazeltine Hydrophone and Retainer Assembly
Fig 2 unknown total cable length.
No depth option, always the same.
Hazeltine Hydrophone and Retainer Assembly
Fig 3 latch mechanism (not clear how it works)
Hazeltine Hydrophone and Retainer Assembly
Looking for Hazeltine patent that might cover this, no luck, but maybe related ideas like lines of hydrophones.
5132940 Current source preamplifier for hydrophone beamforming,  James A. Culbert, Hazeltine Corp, 1992-07-21 - listening buoys
2891232 Hydrophone for directional listening buoy, Heinrich O Benecke, 1959-06-16 -
2898589 Hemispherical acoustic phase compensator, Abbott Frank Riley, 1959-08-04 - makes use of a miniature replica
3037185 Sonar apparatus and components, Gerhard H Dewitz, Cgs Lab Inc, 1962-05-29 - "In one embodiment of this invention, which will be described presently, a scanning system is provided which does not depend upon mechanically moving parts for controlling the direction of the transmitted beam or the direction of greatest sensitivity of the receiving apparatus, and which permits continuous high speed scanning over any desired area." i.e. beamforming
3064235 Audible broadband sonar monitor, Keith E Geren, 1962-11-13 - a broadband ( kHz to 100 kHz) hydrophone driven receiver with special signal processing for hearing "single ping" sonar at an unknown frequency
3116471 Radio sonobuoy system, Jesse J Coop, 1963-12-31 - directional sound receiving beam coupled with magnetic compass do give directional information DIFAR
3281769 Transducer apparatus, Theodor F Hueter, Honeywell Inc, 1966-10-25 - probably for underwater locator beacon since "for use at extreme depths."
3559160 Spatial surveying and target detection system, Bradshaw Burnham, US Secretary of Navy, Filed: 1963-11-07, Pub: 1971-01-26 "10,000 hydrophones", tubes SOSUS?
3903407 Method for correlating frequency-modulated signals, Bradshaw Burnham, US Secretary of Navy, Filed: 1963-12-11, Pub: 1975-09-02 - photo-optical, SOSUS?
3905320 Low frequency homing system, William J Mueller, US Secretary of Navy, 1975-09-16 - homing system for torpedoes "The low frequency homing system of this invention utilizes lines of hydrophones or transducers spaced along the port and starboard sides, and along the top and bottom sides of a torpedo."
2409632 Guiding means for self-propelled torpedoes, Robert W King, AT&T Corp, 1946-10-22 - active ultrasonic SONAR
4423494 Beam steerable sonar array, Kenneth W. Groves, John D. Lea, Sperry Corp, 1983-12-27 -
6088299 Vertical hydrophone array, Louis W. Erath, Phillip Sam Bull, Syntron Inc, 2000-07-11 -  seismic exploration cable includes time delay elements: "traveling wave antenna"

Roswell Connection

While studying the MH370 disappearance and search (March - April 2014) and in particular the 37.5 kHz ultrasonic pings from the Cockpit Voice Recorder (Wiki: CVR) and the Flight Data Recorder (Wiki: FDR) generated by the Underwater Locator Beacon (Wiki: ULB).  This lead to the SOFAR channel (Wiki) and the thermocline (Wiki).  A way to determine the depth of the thermocline is to drop an SSQ-36 (see SSQ-36 above) or other Bathythermograph such as the SSXBT (Wiki: BT).  Note that the maximum depth of the SSQ-36 is 800 meters, not the center of the SOFAR channel which might be at 1000 meters, but low enough to be in the channel. 

2587301 Method of sound transmission, Ewing William M, (Wiki), Us Navy, Filed: Nov 16, 1945 (7 year delay), Pub: Feb 26, 1952, 67/127 - "sound channel" , Fig 7 map showing listening staations: Aleutian Islands, Kurie Islands, Marinas, Saipan Islands & Midway.  Explosion set for 675 fathoms.
2601245 Underwater signaling device, Charles F Bowersett, Filed: Jan 30, 1948, Pub: Jun 24, 1952, 181/142, 102/229, 181/125 -  contains explosives 
Long range explosive sonobuoy, George Sipkin, Filed: Oct 6, 1949, (7 year delay), Pub: Aug 21, 1956, - explains sound channel

It turns out that a stock sonobuoy can not hear the 37.5 kHz ULB since the highest frequency they can hear is 20 kHz (see DIFAR above).  So a stock sonobuoy can not be used to find the CVR or FDR.  But all the information about sound propagation in water is applicable to normal sonobuoy operation.

Note that military passive SONAR (Wiki) is designed to pick up the sounds generated by surface ships, submarines and torpedos (maybe 10 Hz to 20 kHz), not aircraft black boxes at 37 kHz.  This frequency range does include a lot of sea life so a sonar man needs to know what they sound like, or his computer knows.   If you rub your thumb and index fingers together you generate an ultrasonic sound, like that used by Bats, in the 30 kHz region but no normal audio.

Maurice Ewing (Wiki) who discovered the SOFAR channel (Wiki) figured out that the speed of sound vs. depth would cause sound to be "piped" if it was in the SOFAR channel rather than being omnidirectional if not in the channel.  He extrapolated that idea to the atmosphere where the speed of sound vs altitude curve has the same shape as the one for speed of sound vs depth in water and so there should also be an atmospheric channel ( it turned out to be at about 50,000 feet whereas the ocean channel is at about 1000 meters deep).  By putting microphones (in the 1940s the state of the art microphone technology was the Disk Microphone (used by Orson Wells - Wiki), or disk for short like we now say radio instead of Radio Receiver) in the channel you can hear sounds from very very far away that you can not hear any other way.  Disk microphones are called "spring microphones" on eBay.  For example rocket launches or atomic bomb testing.
Richard Muller Physics Lecture 11 - Waves 1 

Wiki: Sofar bomb - Naval Airborne Ordnance NAVPERS 10826-A (Aircraft Reference book 17) describes the SOFAR bomb on pages 195 & 196 as "a 4-pound cylinder casing carrying the explosive, and a head which enables the operator to select one of the six possible depth settings between 1,500 and 4,000 feet."  There is a Pacific ocean map showing receiving stations at Point Arena and Point Sur on the California coast and at Kaneone in the Hawaiian islands.

In the book Principles of Underwater Sound by Robert J. Urick (Reference 10) there is an example of the SOFAR bomb on page 415.
Problem: In the sofar method of aviation rescue, a downed aviator drops a 4-lb explosive charge set to detonate on the axis of the deep sound channel.  ow far away can the detonation be heard by a nondirectional hydrophone, also located on the axis of the deep sound channel, at a location of moderate shipping in sea state 3?

Solution: (detailed description of calculation) 4,000 miles.
Then I watched the UC Berkeley Physics 10 - Lecture 11: - Waves I (YouTube, Text)  by Richard Muller (Amazon).  It turns out that the Project Mogul (Wiki 1947 - 1949) used the bulk of a CRT-1 sonobuoy.  They replaced the hydrophone with a string of "Disk Microphones" that was 657 feel long.  He also mentions SOSUS and "Hunt for Red October" in passing.  The SOFAR bomb was used by W.W. II pilots downed in the ocean.  They would throw this hollow metal sphere (SOFAR bomb aka: SOFAR Sphere (Wiki)) into the water and it would sink.  After about 5 minutes it would reach about 1000 meters depth and implode.  The implosion had the energy of about 2 pounds of TNT.  The shore based SOFAR stations would note the time of arrival and triangulate the location of the implosion.  Later the Signals (underwater sound) Mk 22 Mods 0 and 1 were developed to work with the shore stations.  If an enemy captured one of these SOFAR bombs and cut it open it would be very unlikely that they could determine what it was or how it was used.

When Project Mogul flight No. 4 crashed outside Roswell the Air Force reported that "flying disks had been recovered" from the wreakage, but the local paper reported it as a "RAAF Captures Flying Saucer".  Note the change from plural because there were a large number of disk microphones to singular Flying Saucer".
See my Western Electric 387W Disk Microphone web page for an example of a disk microphone.  Note eBay search term "Spring Microphone".
The Wiki page Roswell_UFO_incident - has an image from the Roswell Daily Record, July 8, 1947. The main headline is: "RAAF Captures Flying Saucer On Ranch in Roswell Region".  The subheading is "No Details of Flying Disk Are Revealed". 

This web page was started because of the connection to Vietnam era seismic detectors (outdoor intrusion alarms).  But I still have not determined which sonobuoy was the source for the 2-3/4" diameter cylindrical components of the GSQ-160, if you know please tell me.

In the official Air Force book "The Roswell Report - Fact vs. Fiction in the New Mexico Desert - Headquarters United States Air Force - 1995 - ISBN 0-16-048023-X (free on line as roswell.pdf) - 993 pages see attachment 32, "Report of Findings on Balloon Research", chapter Project MOGUL, pdf-Pg 303 that describes the underwater sound channel and the idea by Dr. Maurice Ewing (Wiki) that there might also be a sound channel in the atmosphere and how to exploit that idea as Project Mogul (Wiki).

A Google Patents search on inassignee:"Gen Mills Inc" balloon will turn up many patents related to the new type balloon good for high altitude
2526719 Balloon construction, Winzen Otto C, Gen Mills Inc, Apr 2, 1948 - key is replacing rubberized fabric with polyethylene (Wiki)
2492800 Fast rising sounding balloon, Isom Langley W, Aug 16, 1948 - key non elastic material.
2767940 Balloon with strengthening elements, Donald F Melton, General Mills Inc, Filed: 1953-11-04 -
2767941 Seam for gored balloons, Frederick J Gegner, Alan A Reid, General Mills Inc, Filed: 1953-11-04 -

In the book An Ocean in Common: American Naval Officers, Scientists, and the Ocean Environment (Ref 4) they mention that the sound channel in the Atlantic ocean is 4,000 feet but in the Pacific it's at 2,500 feet. (page 173).

June 2018: In the book UFO Crash at Roswell: The Genesis of a Modern Myth edited by Benson Saler - There is a chapter on the ML-307 Radar Reflector.

The Project Mogul balloon flights (Wiki) are described as being run as an unclassified program to develop constant altitude balloons, not the actual flights with disk microphones. 
Project Genetrix (Wiki) balloons carried 600 lb. cameras. Ran 1955 to 1958.
2666601 Constant altitude balloon, William F Huch, General Mills Inc, Filed: 1952-02-15, Pub: 1954-01-19
2606443 Exploration of troposphere stratification, George W Gilman, Bell Labs, Filed: 1946-06-14 - shows existence of sound channel, although not called that
3070335 Automatic lift augmentation for balloons , Leland S Bohl, William F Huch, Edward P Ney, John R Winckler, Secretary of the Navy, Filed: 1959-08-04, Pub:
1962-12-25 - has the feel of Skyhook balloon (Wiki) flies at 100,000' (harder to shoot down)
3369774 Balloon envelope structure, Jr Arthur D Struble, Filed: 1961-08-02 -

also see: Radiosonde and New UFO Information April 2014

Black Box for ships

6706966 Hardened voyage data recorder,  L3 Communications Corp, 2004-03-16 - a black box for ships.  Based on the 1974 the Safety of Life at Sea (SOLAS) Convention. - Patent Citations (89) -

Unknown Sonobuoy - What is it?

There are many similarities with the CRT-1, but . . .
It looks like mid 1960s (date code, TO-3 power transistor in power supply, 1xx and 3xx tubes).
Someone has scratched SONOR on one of the sheet metal covers with an arrow pointing down.  This implies it's an active pinging unit rather than a passive listening only unit.
That is reinforced by the large space for batteries.
This is not mine.  Photos and information supplied by Michael, VK4ZKT

UnKS Fig 1
                  Sonobuoy mid 1960s SONAR?
UnKS Fig 2  Tubes may be 12AT7,
not low voltage like in the CRT-1.
                  Sonobuoy mid 1960s SONAR?
UnKS Fig 3
                  Sonobuoy mid 1960s SONAR?
UnKS Fig 4
                  Sonobuoy mid 1960s SONAR?

Unknown Sonobuoy No. 2

I received a couple of emails from John B. who lives in Greece.  He has sent a number of photographs of a sonobuoy that makes use of both tubes and solid state devices.
Fig 1
Unknown Sonobuoy No.
Fig 2
Unknown Sonobuoy No.
Fig 3
Unknown Sonobuoy No.
Fig 4
Unknown Sonobuoy No.
Fig 5
Unknown Sonobuoy No.
Fig 6
Unknown Sonobuoy No.
Fig 7
Unknown Sonobuoy No.
Fig 8
Unknown Sonobuoy No.
Fig 9 Chesapeake Instrument Corp.
Shadyside, MD
Unknown Sonobuoy No.
Fig 10 Hydrophone
Mod. SB 154C
Auditory Capacities in Fish.pdf
5cm dia x 1.5cm thk
barium titanate
-89 decibels (re 1 volt per microbar of sound pressure) and a frequency response essentially flat from 50 cps.

Unknown Sonobuoy No.
Fig 11
Unknown Sonobuoy No.
Fig 12
Unknown Sonobuoy No.
Fig 13
Unknown Sonobuoy No.
Fig 14
Unknown Sonobuoy No.
Fig 15
Unknown Sonobuoy No.
Fig 16
Unknown Sonobuoy No.
Fig 17
Unknown Sonobuoy No.
Fig 18
Unknown Sonobuoy No.
Fig 19
Unknown Sonobuoy No.
Fig 20
Unknown Sonobuoy No.
Fig 21
Unknown Sonobuoy No.
Fig 22
Unknown Sonobuoy No.
Fig 23
Unknown Sonobuoy No.
Fig 24
Unknown Sonobuoy No.
Fig 25
Unknown Sonobuoy No.

Underwater Communications

6856578 Underwater alert system, Daniel J. Magine, Kevin D. Kaschke, Feb 15, 2005, 367/134 - Ocean Technology Systems Diver Recall System DRS-100?

BQC-1 Underwater Telephone (Wiki: Gertude)

Battery powered portable unit in sub escape trunk.
YouTube: Sub Brief: Whiteboard: AN/BQC-1 Underwater Telephone 5:06 - Patreon, Aaron Amick,,

Voice  Mode:
500 yard (1500 feet) range.
Single Side Band (SSB), not the double sideband in the early patents below.
8.3 kHz carrier.

Beacon Mode:
20,000 Yard (11 mile) range.
24 kHz ping once every 30 seconds.

WQC-2 Underwater Telephone

Wired into sub control room.  More power.  8.0875 kHz carrier frequency.

Patents for underwater telephone

2530528 Phase comparator for underwater signaling, John G Kreer, Bell Labs, App: 1944-11-01, Pub: 1950-11-21, - involves balanced modulators and SONAR bearings
2798902 System and method for underwater communication, Kursman Daniel Richard, Sigmund P Rosen, 1957-07-09, - a balanced modulator is used to send or receive a double sideband signal (no carrier).
3181116 Underwater telephone system, William F Gordon, 1965-04-27, 367/132 455/40 367/124 455/73 - 10kHz balanced carrier
3218607 Underwater telephone, Charles R Brock, Reginald J Cyr, Bendix, 1965-11-16, 367/132 128/201.19 455/40 D24/110.2 2/425 379/430 455/575.2 -
3263207 Transistor underwater telephone system, Herbert L West, Francis E Huff, Navy, 1966-07-26, 367/132 330/298 455/40 331/116R - may look like flashlight
3337841 Underwater telephone, Walter N Wainwright, Russell I Mason, Jr Victor Savchuk, Stanley L Ehrlich, Navy, App: 1957-04-09 (SECRET for 10 Years), Pub: 1967-08-22, 367/132 455/40 379/175 381/367 381/375 - balanced modulator
3495209 Underwater communications system, Homer A Engle, 1970-02-10, -

Communication Buoy "Float the Buoy"

4227479 Submarine communications system, Morton Gertler, Lester F. Whicker, Thomas Gibbons, Navy, App: 1962-08-07, (SECRET for 18 years) Pub: 1980-10-14, - TV camera, TV antenna,, VLF antenna, LF antenna (this was prior to satellites).

Submarine Missile Hanger

The Regulus Missile (Wiki) seems related to this patent by the Martin Co.

2735391 Warship
                  Weapons System, Including Aircraft Storing and
                  Launching Arrangement, H.H. Buschers, Glenn L Martin
                  Co, 1956-02-21
2735391 Warship Weapons System, Including Aircraft Storing and Launching Arrangement, H.H. Buschers, Glenn L Martin Co, 1956-02-21, -

2792599 Seal, Gantschnigg Gottfried Karl, Herbert H Buschers, Glenn L Martin Co, 1957-05-21, -

Submerged Signal Ejector (SSE)

3" Launch Tube devices top to bottom:
T-347/SRT Buoy, Radio Transmitting - launched from submarine
Vaisala  RD93 GPS Dropsonde - launched from airplane
SUS: Signal Underwater Sound - launched from airplane
Sippican Ocean Systems SSXBT Model ST-1 Bathythermograph -launched from submarine 

Vaisala RD93 GPS

aka: Submerged Signal and Decoy Ejectors (SSDE)(Wiki) - 12-4-01 Submerged Signal Ejectors  - 6" internal diameter:

These are similar to 100mm diameter torpedo tubes are probably are located in torpedo rooms.  These tubes can be used to launch various devices that fit the 100mm (4") tube.
Countermeasures, emergency beacons, signal flares, small explosive charges and probably a Bathythermograph (would require a way to handle the trailing wire) . . .
T-347/SRT Submarine Rescue buoy that transmits SOS SUB SUNK SOS is about 3-1/4" dia x 40-1/2" long and can be launched using the SSE.

Ref 8 mentions a 3" signal/decoy ejector (pg 69 photo of Bathythermograph & its terminal) that can be used for the Submarine Launched One-way Transmitter (SLOT)(pg 70).  In the Glossary (pg 308) "usually 3-inch".

So are there two different small launch tubes, i.e. 3" and 4" or has one of these become a standard? let me know

2710458 Underwater
                  acoustic decoy
2710458 Underwater acoustic decoy, Reed Donald G, Sec of Navy, Filed: Jun 14, 1945 (10.0 year delay), Pub: Jun 14, 1955, 434/6, 114/20.1, 367/1, 434/25 - passive SONAR training device

Fig 1: either 3x32" or 4x43", most likley 3x32"
Fig 9: either 3x24 or 4x32"

This may or may not be launched from a sub.
2981927 Underwater
                  sound transmitter
2981927 Underwater sound transmitter, Vaughn G Mckenney, Sec of Navy, Filed: Apr 4, 1946 (15 year delay), Pub: Apr 25, 1961, 367/1, 455/18, 114/20.1, 360/6 - returns SONAR pings at same frequency but offset in time (very similar to RADAR countermeasures). see Radar Warning Receiver

Fig 1 shows a length/diameter ratio of 11.5, so if 3" dia then length is 34", if dia is 4" then length is 46".
Since a yard or meter shows up as a practical length then I'd assume this is a 3 x 34" device.

2793589 Buoyancy control device, Atchley Raymond D, Filed: May 3, 1944, (13 year delay), Pub: May 28, 1957, 102/414 -

3379273 Powerful sound impulse generation methods and apparatus, Stephen V Chelminski, Bolt Technology, 1968-04-23, - the "airgun" mentioned by AAron in Sub Brief: Analysis: Seismic Airgun - used for geology of the ocean bottom. 
Has the look and feel of the Gamewell Diaphone Air Horn used at fire stations to call firemen and as a Fog Horn.
5003515 Submarine
                  emergency communication transmitter 
5003515 Submarine emergency communication transmitter, Albert S. Will, Frank C. McLean, Sylvan Wolf, Samuel H. Kauffman, John C. Hetzler, Jr., Charles A. Lewis, George E. Maxim, Secretary Of The Navy, Filed: May 28, 1964, (27 year delay)    Pub: Mar 26, 1991, 367/131, 367/145 -

Image flipped so that it's oriented as if in the water.  There are 7 drop bombs which are released by explosive bolts and they explode after 20 seconds so that their depth will be controlled (probably within the sound channel (see Roswell Connection above).  If the sink rate was the same as the Mk IX depth charge (15 fps) then after 20 seconds it would be down to 300 feet which is too shallow to get into the SOFAR Channel (Wiki).  I suspect the time delay is really much longer to that the drop bombs get into the SOFAR Channel.

The timing of the drop bomb release translated into one of a number of coded messages.

The length/diameter ratio is very small so will not help to determine its dimensions.
5044281 Submarine
                  flare with vertical attitude determination
5044281 Submarine flare with vertical attitude determination, Peter Ramsay, Brian W. Whiffen, Gerald M. Bushnell, Victor Nanut, Robert C. Czigledy, Robert J. Swinton, Maxwell J. Coxhead, Timothy R. Clarke, Australia, Sep 3, 1991, 102/340, 102/224, 102/351, 102/357, 102/354 -

The length/diameter ratio is 12.67, so: 3" x 38" or 4" x 57", seems to indicate it's 3 x 38".


CRT-1 Sonobuoy
Magnetics - Magnetostriction, Sound Bug
Helmholtz coil -
Helmholtz Resonator & Tuning Forks
Torpedoes, Mines, Depth Charges
GEO_ID - TRC-3, PEWS, USQ-42, Turd
GSQ154 - All GSQ-154
GSQ160 - Frequency Disconnect -GSQ-160, USQ-46, TS-2963, PP-6446 - TCw - cylindrical module pinouts.
GSS26 - AN/GSS-26 minimal info
Intrusion Alarm Patents
USQ_Rx - Igloo White, USQ-42, USQ-46 details,
PSR-1 - now on it's own page (July 2007)
Modular Outdoor Intrusion Sensors (REMBASS?)
Astronomy - UFOs - Richard Muller Physics Lecture 11 - Waves 1

P-3C Systems

I lived in Mountain View, California for some decades and Moffett Field was the base for P-3 aircraft.
NASA operated a flying telescope and a U-2 there as well as a giant wind tunnel among many wind tunnels of all kinds.
Just looking up the systems listed for the Update II. Standard Aircraft Characteristics, P-3C Update II.pdf , 12 pages, 1984 -
Data Terminal
Emerg. Trans
Crash  Locator
VHF Comm Group

Harpoon Ctrl

True Airspeed
Central Repeater
Flight Director System
Navigation Set, Radar
Horiz. Situation Ind
Periscope Sextant
OTPI Receiver
Sonobuoy Reference Set
VHF Navigation Group
Inertial Nav System

Non-Acoustical Sensor Data
Compensator ASA-65(V)2
Compensator ASA-65(V)2
MAD ASQ-81(V)2
IRDS VIdeo REc Grp OA-8962/ASH
Disp Grp, Tact Aux (TADS)

Acoustical Sensor Data
Sonar Comp Rec Grp
(Triple Vernier)
Sono Recorder Sys AQH-4(V)2
Sonobuoy Rcvr Sys
CASS (Modified) ASA-76A
Bathythermograph SSQ-36/RO-308
Sea Noise Meter ID-1872A

Data Processing/Display
Tact Disp
Radar Scan Conv
Tact Dsip Grp
Avn Unit Comp
Data Anal Proc Grp
Synchro Conv
Time Code Gen
Dig Dta Rec Rep

ACQ-5 Data Link

This is a data link system based on the aircraft HF-1, HF-2 or UHF-2 radios.  Uses Navy Tactical Data Systems serial protocol which includes symbology.
PP-6140/ACQ-5 Power Supply
C-7790/ACQ-5 Control Monitor - modem control
CV-2528/ACQ-5 Data Terminal Set Converter-Control - 26-bit serial modem in normal use: Clock Select=Master, Control=Operate, then other troubleshooting controls are disabled.
Communications Interface No. 2 - converts 30-bit parallel computer words into 26-bit serial data
Used with Link 11 (Wiki: MIL-STD-6011) and KG-40 (Crypto Museum)crypto.

AIC-22 Aviation Inter Communications

Aircraft intercom using headsets. The prior system was the AIC-18.  There were complaints of the radios interfering with the intercom and an investigation showed that using fiber optics would decrease the problem.
AM-3364/AIC-22(V) Interconnecting Box Amplifier

ARC-143 UHF Radio

Control head

ARC-161 HF Radio

C-9245/ARC-161 Control Box
RT-1000/ARC-161 Receiver Transmitter
AM-6561/ARC-161 RF Amplifier
CU-2070/ARC Antenna Coupler
works with TSEC/KY-75 Remote Control Unit


Floating buoy that transmits on 8.364 MHz and 243.0 MHz.  1/4 Watt output power on both bands and a 3 day battery capacity.  Looks like a replacement for the Gibson Girl.  A 9 foot ling telescoping HF antenna will not be very efficient on HF (0.076 wavelength).

AQA-7 Sonar Computer Recorder Group (Triple Vernier)

"That system was the AQA-7 that "burned" the recorded data on paper. In it's original form it was call the "Jezebel" and we'd often call the acoustic operators "Jez" even after it was long gone from the aircraft. It would scroll like a fax machine and at the end of the mission, the paper would be turned in to the debriefing gang for reconstruction. One positive thing was the paper was an immediate visible replay of the information gained by the sonobuoys and the operators would also write and do computations on the paper itself. Plus an operator could cut off the paper and remove from the machine and review back in time while on the mission to maybe see if contact was missed. The negative was the nasty smell this machine produced!!!!!!!

Initially the buoys were "Lofar", or basically the buoy would detect a sound and give the operator a circle around the buoy and it would take multiple buoys to localize to a small area to search. "Difar" buoys, which provide sound recordings, but more importantly, direction from the buoy were the next important tool to be developed and replaced Lofar. Two or three buoys with lines pointing to a noise source and there it is where those lines intersect.

The USN went away from the AQA-7 when the P-3C Update III came on line in the mid 1980s. The acoustic processing system was now all computerized, Lofar buoys were a thing of the past. The new system was called the UYS-1, and the big and probably final upgrade to that system was introduction "CHEX" or channel expansion, allowing the aircrews to have 99 channel capabilities for buoy channel numbers of buoys instead of only 32 (see Channels above). Now, all the data is recorded on tapes that had to be replayed on ground based computer systems to review the mission and compare with operator notes. (Operators could not do this in-flight). That system is what is featured in the Hickory Aviation Museum's P-3C (See below), with plasma panels to enter data and manipulate the buoys. When flying, the operator on the right was the lead, he'd usually do the Difar work, which was passive only, just listening for noise. The other operator was usually in training and would help and also do the Dicass, or active buoys should they be authorized. Dicass would provide a range and bearing from buoy to target with burst of energy, just like sonar.. I flew on aircraft with both systems, and a lot comes down to the quality of the operator and numerous other factors such as oceanographic conditions, and of course, the target itself. Hope that answers the question, if not, let me know., I had 3k+ hours flying P-3C?s." . . . . Brian Harrison

"I concur with what Bill said for the most part. The AQA-7 operators, SS1 and SS2, didn't provide circles. They would provide frequency of the signal, its signal strength, time of detection and loss of signal. Based on the signal strengths, the TACCO could draw circles around the buoys on his display to help localize the target. The greater the signal strength, the smaller the circle. Where the circles intersected, if they did, could provide possible target locations. That was only useful if the signal was direct path (nearby the buoy), but not if the signal was actually from a convergence Zone (CZ) (much farther away). The TACCO would use tactics to determine between the two. The tactics would include more Lofar buoys and/or some Difar buoys." Brian's brother.
BQC-1 Underwater Telephone (Wiki: Gertude)

YouTube: Sub Brief: Whiteboard: AN/BQC-1 Underwater Telephone 5:06 - Patreon, Aaron Amick,,

"Float the Buoy" 4227479 Submarine communications system, Morton Gertler, Lester F. Whicker, Thomas Gibbons, Navy, App: 1962-08-07, (SECRET for 18 years) Pub: 1980-10-14, - TV camera, TV antenna,, VLF antenna, LF antenna (this was prior to satellites).


Bombshell: The Hedy Lamarr Story - IMDB - Claims that the Navy used her invention on DIFAR sonobuoys in the RF link back to the airplane.  The reference cited is:
Which no longer is on line and does not have a copy.
But that's a false claim since the link back to the aircraft is non encrypted. and doesn't need to be before the existence of satellites.  There's no enemy to hear the transmission.  Even today with satellites it's questionable if there's any value in encrypting the link.

Books & References

Also see: Aircraft Reference books, Submarine References, Torpedo Reference Books,

Ref 1. Naval Institute Guide to the Ships and Aircraft of the U.S. Fleet, 18th Edition (2005) by Norman Polmar
Ref 2. The Ears of Air ASW: A history of U.S. Navy Sonobuoys (2008) - Holler, Horbach & McEachem
Ref 3.Scientists Against Time, James Phinney Baxter, 3rd ed, 1946 - 1952 (Wiki)
Ref 4. An Ocean in Common: American Naval Officers, Scientists, and the Ocean Environment, Gary E. Weir, 2001, ISBN: 1-58544-114-7
Ref 5. Design and Construction of Crystal Transducers, NDRC Summary Report Vol 12, 1946 (407 pages) - University of California Division of War Research [UCDWR]
Ref 6. The Evolution of the Sonobuoy from World War II to the Cold War, Holler, Jan 2014.
Ref 7. Sonobuoy History from a UK Perspective: RAE Farnborough's Role in Airborne Anti-Submarine Warfare, Clive Radley, 2016 -Chapter 4: The first operational Sonobuoy, the AN/CRT-1, used by the USA and the UK in World War 2.
Ref 8.
Submarine (Tom Clancy's Military Reference), 2003 - mentions 3" signal/decoy ejector (pg 69), Submarine Launched Oneway Transmitter (SLOT) also uses the 3" launch tube (pg 70)
Ref 9. History  of Communications-Electronics  in the  United  States  Navy, L.  S.  Howeth, 1963 - U.S. Early Radio History - Ch 26: Dev of Underwater Sound and Detection Equipment, pg 297
Ref 10. Principles of Underwater Sound by Robert J. Urick
Ref 11. Wiring Vietnam: The Electronic Wall, Anthony J. Tambini,2007 - some mention of sonobuoys (Exhibits at: Patuxent River Naval Air Museum & USS Hornet Museum).
Ref 12. History of Ultra Electronics Maritime Systems Inc. - The History of Sonobuoys - "from October 1942 to the war’s end in 1945, the U.S. Navy had ordered 150,000 sonobuoys and 7,500 sonobuoy receivers".  An NDRC document actually states 160,000 so reality is 150/160k.
Ref 13. Batcats: The United States Air Force 553rd Reconnaissance Wing in Southeast Asia by Sikora & Westin, 2003 -
Ref 14. EC-47: Acoubuoy, Spikebuoy, Muscle Shoals and Igloo White.pdf by Chris Jeppeson 1999 -
Ref 15. Photo 10-26-45 Acme news: Arthur Gremer, design engineer; Francis Burger, supervising engineer; George Rogers, chief engineer; Mark Grant, design engineer.  Announced to public around October 1945.
Ref 16. History of Communications-Electronics in the United  States Navy, 1963 (html, pdf)
Ch XXVI Development of Underwater Sound and Detection Equipment (html)
Ch XXXI The Navy and the Patent Situation (html) - W.W. I
Ref 17. Probing The Oceans For Submarines -- A History of the AN/SQS-26 Long-Range, Echo-Ranging Sonar (a538018.pdf) 266 pgs
1. Introduction
2. History
3. Launching Program
4. Full Scale Experimentation & Development
5. Prototype Testing
6. Supporting R&D
7. Rubber Dome Window
8. Equip Ops & Tactical Employment
9. Fleet Performance
10 Conclusions
11. End Notes
App A: Event Chronology
App B: Personnel by employer
Looking for patents based on names mentioned in Ref 17.
2434469 Pressure-proof reproducer, William A Myers, App: 1944-07-01, Pub: 1948-01-13, -
2537052 Tuning means for ultra high frequency signal generators, Andrew V Haeff, Charles B Smith, Robert H Mellen, App: 1945-08-30, Pub: 1951-01-09, - 
2563829 Cable seal, James W Fitzgerald, Burton G Hurdle, Carlton L Morse, App: 1946-04-17, Pub: 1951-08-14, -
2694868 Echo repeater, Edwin M Mcmillan, William A Myers, App: 1943-08-03, Pub: 1954-11-23, -
3209314 Sound beacon, William A Myers, Vaughn G Mckenney, App: 1944-08-09, (SECRET for 21 YEARS), Pub: 1965-09-28, -
3229245 Echo ranging display system, Burton G Hurdle, Jr Robert J Mackey, 1966-01-11, -
3246289 Resonant underwater hydrodynamic acoustic projector, Robert H Mellen, 1966-04-12, -
3307142 Three-color echo ranging display, Harold J Doebler, 1967-02-28,
3403374 Underwater hydrodynamic acoustic projector, Robert H Mellen, Berman Robert, Kenneth L Moothart, Navy, 1968-09-24, -
4473896 Tactical Expendable Device, Harrison T. Loeser, Harold J. Doebler, Navy, 1984-09-25, -
5526323 Method and apparatus for interpretation of sonar signals, Robert M. Chapman, GD, App: 1965-09-28, (SECRET 31 YEARS) Pub: 1996-06-11
5911172 Retractable underwater turret, Kyrill V. Korolenko, Navy, 1999-06-08, -
6052335 Multiple-frequency sonar system, Kyrill V. Korolenko, Navy, 2000-04-18, -
6229761 Estimating ship velocity through the water and over the ground, Kyrill V. Korolenko, Henry Ralph D'Amelia, Henry Robert D'Amelia, Navy, 2001-05-08, -
6868768 Surf zone mine clearance and assault system, Thomas J. Gieseke, Kyrill V. Korolenko, 2005-03-22, -
7940602 Real-time system and method of underwater depth discrepancy detection, recordation and alarm notification, Kyrill V. Korolenko, Navy,2011-05-10, -
Ref 18. Hitler's Naval War, Cajus Bekker, 1971 - Around 1939 the German Subs had pretty much the same problems that the U.S. had starting in 1942.  Torpedoes that ran deep, Magnetic exploders that did not work, contact exploders that did not work.  Haven't yet seen circular running mentioned.
Ref 19. US Naval Weapons, Norman Friedman, 1983 (no copyright notice) - Excellent information not in other books about how decisions were made.
1. Guns (surface fire)
2. Fleet air defense before 1945
3. Underwater ordnance
4. Fleet are defense after 1945
5. Air-to-air weapons - See China Lake
6. Surface-to-air missiles
Appendidces: Guns, Fire Control Systems, Gun Mounts, Armor Penetration, Airborne Radars, Sonars, Sonobuoys, Torpedoes, Mines, Depth Charges, ASW Projectors, ASW Missiles, Guided Missile Launching Systems, Surface-to-air Missiles, Bombs, Nuclear Weapons, Air-to-Surface Missiles, Surface-to-Surface missiles.
Ref 21. Pushing Horizon: Seventy-Five Years of High Stakes Science, Ivan Amato, 1998 -
Ref 20, Ref 22. Principles and Applications of Underwater Sound, Originally Issued as Summary Technical Report of Division 6, NDRC, Vol. 7, 1946, Reprinted...1968 (pdf 321 pages)  (Print on Demand) [at the time I ordered the print on demand book there was no free on line copy.  Maybe ordering the POD book freed it up?]
Part 1: Basic Principles of Underwater Sound
Part 2: Echo Ranging
Part 3: Listening

Ref 23. Naval War College Newport Papers 16; The Third Battle, Innovation in the U.S. Navy's silent Cold War struggle with Soviet Submarines, Owen R. Cote Jr, 2003
This is an excellent overview of the cold war ASW approach by aircraft, surface ships and other submarines.
The USS Nautilus (SSN-571) had the machinery anchored to the hull and so generated a large amount of noise.  That led to a new class of subs using "rafts" to isolate machinery and dampened flexible tubing to move water in or out to lower the acoustic signature of our subs.

1. From Holland to the Second Battle (end of W.W.II), the first 50 years
2. Phase 1: German Type XXI & early cold war - SOFAR channel,
3. Phase 2: ASW & the two Nuclear Revolutions, 1950 - 1960 -
BQR-2 (Wiki), BQR-4 (Wiki), p32:CRT-1, SSQ-2 (JPROC), LOFAR
QHB sonar: scanning, 25 khz, 19" trans, 1,800 yds @ 20 knots
SQS-4 sonar: 15 khz, 5' array, 8,000 yds (DASH, QH-50)
SQS-23 sonar: 5 khz, 8' array, 10,000 yds
SQS-26 sonar (Wiki): 3.5 khz, 11 - 40 miles
HENs (Wiki: Hotel, Echo, November)
4. Phase 3: ASW and the Happy Time, 1960-1980
P-3 Orion (Wiki)
LAMPS (see: AM-6536/ALR-54 LAMPS Radar Warning Receiver Front-end)
5. Phase 4: ASW & accoustic Parity, 1980-1990
"Because the Akulas did not produce powerful, continuous, narrowband tonals, transient tonals often provided the best initial detection opportunities at long range."
6. Forth Battle? Subs & ASW after the cold war

Ref 24. Aircraft and Submarines: The Story of the Invention, Development, and Present-Day Uses of War's Newest Weapons, Willis J. Abbot, 1918, 567pgs (pdf)


ASW To Catch a Shadow - Anti-submarine Warfare, P-3 Orion, USS Scorpion 20850 HD - 29 minutes
Goblin on the Doorstep - ASW Anti-submarine Warfare 20870 HD - 29 minutes -Collecting microscope slide from early Bathythermograph,
ASW: Tracking the Threat 1982 US Navy Training Film; Anti-Submarine Warfare - 23 min - Launching Bathythermograph -
BT data after launch of BT
BT data after launch of
U.S. NAVY SONOBUOY INDICATOR GROUP AN/AQA-1 ANTI-SUBMARINE WARFARE FILM 51114 (28:53) -  17.5 minutes @2:16: ANB-H-1 Headphones -
Works with:
R-316A Dual receive channel sonobuoy receiver - 16 frequency channels
SSQ-15 Range only (sends out pings every 5 seconds)
SSQ-2b non-directional (Explosive type)
U.S. NAVY MK-84 SONOBUOY TRAINING FILM SIGNAL UNDERWATER SOUND (SUS) 81204  - 12 minutes - Sound Underwater Signal Mk 84 Mod 0. Non Explosive,  can be set to one of 4 preset codes. 2.95 & 3.55 kHz: can be heard with: AN/BQR-2, AN/BQR-7, AN/UQC underwater telephone on the third harmonic (aprox. 10 kHz)
Coordinated Anti-Submarine Warfare - SONAR, Sonobuoys, USS Stein, USS Badger 20890 HD - 19 minutes - about fleet operations
ASW The Submariners - USS Shark, Anti-submarine Warfare Maneuvers 20800 HD - 29 minutes - @12:22: USS Holland First US sub
Hunter Killer Anti-Submarine Wwarfare U.S. Navy Film 30102 - 21 minutes - Edward R. Murrow (Wiki) - Prop planes
Blind Man's Bluff - History Channel Documentary - 1hr 35min - Some factual errors, see: SOSUS
HD Historic Stock Footage AERIAL ANTI-SUBMARINE WARFARE - @4:34 MAD chart output,
The Guide To Submarines Documentary - welldone
Inside a Navy anti-Submarine Lockheed P-3 Orion Aircraft - Moffett Field Museum -14 -
Visualizing Humpback Whale Calls using DIFAR Sonobuoy -
Modern Sonar Sounds and other Sounds of the Sea - LOFAR
Lockheed P-3 Orion Training Mission- Part 1, Part 2 -
P-3 Orion 50th Anniversary -
Project Tinkertoy (IC Precursor) 1953 US Navy; Automated Manufacturing of Modular Electronics - @4:43 shows Sonobuoy (or?) -
Submarine Communications: "Signal, Underwater Sound (SUS) Mark 84" US Navy Training Film -
P3 Orion SSQ-801E BARRA Sonobuoy deployment (1:28) - deploys into a 3 dimensional structure
Greyhounds of the Sea - History of the U.S. Navy Destroyer 80260 , 26:53 - narration by Jack Web. (new movie "Greyhound", 2020 IMDB -
Sub Brief: A Beginner's Guide #4: Target Motion Analysis (TMA) -(Wiki)


CRT-1B Sonobuoy
CRT-3 BC-778 Gibson Girl Survival Beacon Transmitter SCR-578
Helmholtz Coil
   (Helmholtz Resonator)
MIL-S-5807A Sextant, Aircraft, Periscopic (used on the P-3, see Hickory Aviation Museum virtual tour below)
SSQ-57 LOFAR Sonobuoy
T-347/SRT Buoy, Radio Transmitting 


Hickory Aviation Museum - P3-C interactive tour - Grab circle behind pilot's seat and look up to see this periscope sextant mounted in ceiling of P-3.
The Cutting Edge ASWS-3 Viking  1980 VS-24 (23:50 training video)
PRC68, Alpha Index, Products for SaleBrooke's Military Information page -

page created 22 Oct 20112