After a parachute drop someone
ground needs to find the cargo. This 28 channel receiver
designed to be worn on the left wrist and the LEDs help to
beacon transmitter attached to the cargo. There is a 10
LED bar graph to indicate distance to the beacon
transmitter. This is a currently fielded
and bottom lids are sealed to the main body and so it's not
be repaired. Uses surface mount
This was one of the first military electronics units to make
surface mount technology. The parts so far all appear to
standard part numbers, not custom ICs.
This program was shelved when GPS went operational. My
unit has a 1983 contract number and serial No. 110.
I've heard that when the payload is dropped the aircraft that
dropped it has a way to come up with Lat & Lon data that
relayed to the ground crew who only need a common GPS
1. Attach Antenna -
Turn to Tighten.
2. Attach Receiver to left wrist with antenna on
outside of arm.
3. Turn knob to assigned channel (1 to 28).
4. Test battery by pushing toggle switch to BAT
position. If yellow light does not illuminate, replace
(or connect antenna).
5. Raise left are and turn until green (corner)
light illuminates. Walk in direction arm points.
6. Yellow lights on end of receiver show relative
to assembly point. TRN on indicates receiption of active
transmitted signal. Other lights move from left to right
The 9 volt battery goes into a
pouch that's part of the strap system that holds the receiver
on the left wrist.
(see below) clearly shows in Fig 6 that both loops and the
sense antenna are inside the case so the connector has some
purpose. Patent 4724442 (see below) mentions using
antennas which might be the purpose of the connector.
external antenna system is not being used there is some jumper
connector has one 0.070" dia pin (pin #1) and three 0.060" dia
pins (pins # 2, 3 & 4). It has a plastic body with
male threads. I don't see any markings on it. The
diameter is about 0.692" If If you know the model of the
connector please let
When a fresh 9 volt battery is
connected and the toggle switch held in the "BAT" position the
LED does not light. Normally this would indicate a bad
or missing antenna. When the toggle is held in the
and a screwdriver is used to randomly short pins in the
connector the yellow LED does light.
small ball of aluminum foil wedged into the connector
contacting pins 1
and 3 causes the BAT test to light the yellow LED next to the
switch. Also the signal strength yellow LEDs near
flickering but the yellow LED closest to "TRN" is off. I
this is the proper condition at this stage.
The plot shown in the photo to the left was made with:
the toggle switch =On
Chan 21 (# next to LED)
connector pins 1 & 3 shorted.
spectrum analyzer shows
new signals at:
164.6875 @ -77 dBm, 175.000 MHz @ -74 dBm, 185.3125 MHz @ -76
dBm and 195.625 MHz # -77 dBm.
Note that the adjacent gaps are all equal to 10.3125 MHz
The synthized LO seems to go
176.720 MHz for channel 1 to 174.425 MHz for channel 28 so
each step is
85 kHz. Typically when the frequency goes down as the
number goes up the LO is above the RF input by the IF.
span of the LO is greater than the common 455 kHz IF the
likley IF is 10.7 MHz. So making a slight tweak to the
frequencies moves them to:
Chan 1: 176.700 MHz LO - 10.7 IF = 166.000 MHz
Chan 28: 174.405 MHz LO - 10.7 IF = 163.705 MHz RF input
The antenna consists of both a loop and a sense antenna and
these are contained inside the box.
You can see the 9 v battery pouch in the photo at the left and
cable going into the receiver. The LED in the near
probably the Green To/From LED that's green when you are
Pins 1 (large dia) and 2 are connected toghther. The
test LED lights when pins 1 & 3, 2 & 3, 3 & 4 are
toghther. But not 2 &4? This may mean that
two different antennas that can be used. If you know
order to open the lid the four screws were removed and a dead
rubber hammer used to crack the glue used to seal the lid to the
box. The bottom lid has not yet succumbed to the hammer so
blows are needed to get it off.
photo shows the top lid removed and the digital PCB hinged
In the bulges beside the channel switch and the battery wire are
turn coils oriented at right angles to each other and each has a
variable trim cap. These are the two orthogonal loop
The Class 342/4
to be common to both of the E-systems patents for the DZAAS and
as of 7 Jan 2007 there are 7810 patents in the linked search.
Single null miniature direction finder
March 26, 1991, , E-Systems, Inc., 342/429
A single null miniature
direction finder which may be worn on the arm of the user and
is fully automatic in operation. Signals from a single loop
antenna and a sense antenna are summed; however, the amplitude
of the sense signal is adjusted at first and second phase
angles and the phase of the sense antenna is automatically
switched from the first phase angle to the second phase angle
prior to summing to produce either a single null or a no null
pattern. These patterns are compared to each other as the user
extends his arm horizontally and rotates his body. When the
null occurs an indicator gives the relative direction to the
Method and apparatus for loop direction finding with no
Feb 9, 1988, E-Systems, Inc. 342/434 - uses two loops and a
antenna. Replaced by 5003316 that uses only one loop and a
sense antenna. Includes 28 channel switch and LED
This patent mentions Contract DAAK20-83-C-0639 which is the
number on the DZAAS label. This patents olso shows a 28
The below patents relate to direction finding
Method and apparatus for determining location of
Jan 6, 1998, E-Systems, Inc.342/47 ; 342/13; 342/147; 342/193;
- The locator device transmits a pulsed signal that's close to
unknown transmitters frequency. This causes
distortion to occur in the unknown transmitter. By
time from sending the pulse to the time when the 3rd order IM
signal arrives an estimate of the distance to the unknown
is calculated. The power level of the interrogating signal
Single antenna direction-finding system
March 26, 1996, E-Systems, Inc. 342/451 ; 701/300 - not DZAAS
but instead intended for use on an aircraft.
Position and direction finding instrument
Oct 24, 1995, Georgia Tech Research Corporation, 342/357.08
Path finder/tracker system
Feb 28, 1995, John & Richard Ubaldo, 343/702 ; 33/290;
Discrete fourier transform direction finding apparatus
Oct 24, 1989, E-Systems, Inc., 342/417 ; 342/194; 342/195
Dec 18, 1984, Racal, 342/432 ; 342/433
VHF Directional receiver
October 18, 1983, United States of America as represented by the
342/419 ; 343/767; 455/269; 455/351; D10/65 - VHF slot antenna
conductive tube to earpiece for covert operation
Jan 11, 1977, United States of America as represented by the
342/419 ; 455/333; 455/351; D10/65 - CB radio by channel
Nondisruptive ADF system April 21, 1981, United States of
America as represented by the FCC, 342/434
342/436; 342/438 - does not disturb the modulation like
doppler type DF sets
Direction finder antenna and system
Oct 17, 1978, E-Systems, Inc., 342/424 ; 343/728 - uses crossed
loops & sense antenna PLUT a horizontal loop to detect sky
DIRECTION FINDER RECEIVER DZ-2 CRV-46152 28 VOLTS DC this is an
tube type aircraft receiver. Not sure if it's also a Drop
type radio or general D.F. radio.
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