Sonobuoy Based Outdoor Intrusion Detectors

Brooke Clarke 2011 - 2015

    CNU-239/E Shipping Tube 
    Radio Channels
        Black Box Beacon Transmitter
    DIrectional Frequency Analysis & Recording type acoustic sensor (DIFAR)
    Reserve Batteries
    Table of Sonobuoys
    Sippican Ocean Systems SSXBT Model ST-1
Sonobuoy Aircraft Systems
Outdoor Intrusion Detectors based on Sonobuoy Technology
    1st Generation
USQ-42 Receiver
R-1617A/USQ-46 Receiver
ID-1721 Indicator WANTED TO BUY
PP6446A/USQ-46 Power Supply    
Magnetic Anomaly Detector (MAD)
Roswell Connection
Unknown Sonobuoy - What is it?
Underwater Communications


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

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.  The explosive type active SONAR is good at detecting these subs.


The word sono-buoy is based on sound and a floating object.

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, 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

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.

Bathythermograph (Wiki: BT)

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.

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 kHz ping made by Cockpit Voice Recorders or Flight Data Recorders.  The FAA and Navy need to coordinate this.

Sonobuoy 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.

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.
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.

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.

3rd Generation

At some point (When?) 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 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?

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

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

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 Anomaly Detector (MAD) Patents

2406870 Apparatus for responding to magnetic fields, Vacquier Victor VGulf Research Development Co, filed: Jul 21, 1941,
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.d
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
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
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"

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

Bathythermograph Patents

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

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)

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 -

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

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.
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 - 

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.

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:

Salt water activated silver chloride

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

RDRH Feb 1943

6 channels

separate web page

AN/SSQ-1 upgraded
not UK SSQ-20


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


Julie explosive

AN/SSQ-15 Julie RO B-size

Julie  1956
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.
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

single hydrophone

(replaced Julie explosive system)
active ping omni directional range only
replaced by SSQ-50

replacedd by SSQ-41B

26 Feb 1981


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.

10 to 10,000 Hz

FM sweeps

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

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

" adds RF command function selection




30 July 1997

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










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
EFS: Electronic Function Selector (RF Chan, Life, Depth, Sensor type, AGC)
HIDAR: High Dynamic Range DIFAR
LOFAR: LOw Frequency Analysis & Recording
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
SUS: Signal Underwater Sound (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

Sonobuoy Aircraft Systems

An Aircraft Control Panel for ASA-20 Julie explosive echo ranging device & AQA-1 Sonobuoy Indicator/Tracker,

Aircraft Sonobuoy Control Panel Control
Drift - Compute - Reset

PDI: BDHI: 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

ASA-20 Sonobuoy Recorder "Jezebel".

The AQA-5 is a 4 channel paper chart recorder.
Youtube video: AN/AQA-5 Acoustic Charts Recorder
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)
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 repition 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.

Sippican Ocean Systems SSXBT Model ST-1

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 abord 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 onboard 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.


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. 

Outdoor Intrusion Detectors based on Sonobuoy Technology

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."


(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 it and protrct 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.

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



Patents, Sonobuoy

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
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
2420676 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.

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

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 -
2644243 Control Compass, (Navy), 361/280; 33/363.00Q, Jul 1953 -
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

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, (Navy),  Mar 19 1958
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'.

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

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 -
3377615 Compliant suspension system, Sparton Corp, Apr 9, 1968
3460058 Radio Sonobuoy, (ITT), Aug 5, 1969, 367/4 - operates below thermocline
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
3786403 Underwater Acoustical Detection, Navy, Jan 1, 1974, 367/4; 441/25; 441/26 - 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 -
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 -
4114137 Directional Sonobuoy, (Navy), 367/171; 441/1; 441/28, Sep 12 1978

4143349 Cable depth selector and coil shunt penetrator, (Bunker Ramo Corporation), Mar 6, 1979, 367/4, 441/1, 439/391 -
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 -
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 -
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 -
6400645 Sonobuoy Apparatus, (Navy), Jun 4, 2002, 367/4; 367/3; 367/153 - opens sort of like an 8-sided umbrella

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
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 -


Photo from Wiki Sonobuoy page

From Ships and Aircraft of the U.S. Fleet (2005):
The p-3C 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.
          being loadeed on P-3 Orion from outside prior to takeoff
2707904 Sonobuoy Dispensers, Breeze Corp, May 10, 1955, 89/1.51; 367/3 - revolver,
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 -

Reserve Battery

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.

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 Swquentially 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 -

Magnetic Anomaly Detector (MAD) (Wiki)

When I lived in Mountain View it was a very common sight to see a P-3 Orion landing or taking off from Moffett Field Naval Air Station.  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 2 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)


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.

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

Roswell Connection

While studying the MH370 disappearance and search (March - April 2014) and in particular the 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 (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. 

2760180 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.  For example rocket launches or atomic bomb testing.
Richard Muller Physics Lecture 11 - Waves 1 
Wiki: Sofar bomb

Then I watched the UC Berkeley Physics 10 - Lecture 11: - Waves I (YouTube, Text)  by Richard Muller.  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".  (PS I'm looking for a source document for the "flying disks").

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.

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 it 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?

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?


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


Naval Institute Guide to the Ships and Aircraft of the U.S. Fleet, 18th Edition (2005) by Norman Polmar
The Ears of Air ASW: A history of U.S. Navy Sonobuoys (2008) - Holler, Horbach & McEachem


PRC68, Alpha Index, Products for SaleBrooke's Military Information page -

page created 22 Oct 20112