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AID
  
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Bird Dog 360XT
Directional tracking system

Bird Dog 360XT, abbreviated BD-360XT, is a directional tracking system developed around 1995 by Audio Intelligence Devices (AID) in Dearfield Beach (Florida, USA). It consists of an RX-360 radio direc­tion finder (RDF) with four antennas, and a TX-602D motion-activated tracking trans­mitter with a strong magnet that is typically hidden under the car of a person under surveillance.

The system was used by law enforce­ment and intelligence agencies like FBI and CIA in the years before GPS and GSM became main­stream. It re­quires a VHF transmitter to be co­vertly attached to the bottom of a suspect's car by means of a strong magnet, with a small an­ten­na hanging down. A nearby surveillance vehicle was then able to track the car's move­ments unobtrusively.

The surveillance vehicle must be fitted with four identical antennas that are mounted on the roof. They are connected to the RX-360 directional receiver which is mounted inside the vehicle.
  

When driving, a digital compass near the dashboard shows the direction to the target (i.e. the beacon). The best results are obtained when using a compatible Bird Dog tracking transmitter like the TX-602D that is supplied with the kit. These beacons transmit a modulated pulse train with adjustable interval. As a result, they can operate for six days on a single set of three 9V alkaline batteries. In addition, the beacon transmits a status signal that indicates whether the vehicle is in motion. Using the system with regular Continuous Wave (CW) transmitters is also pos­sible, but without the motion detection capability. The RX-360 receiver can also be used for monitoring regular listening devices in the same VHF-H band, but without direction finding capability.

Items in the bottom case shell
RX-360 direction finding receiver
Front panel
Rear panel
Readout unit (compass)
Antenna set with magnet mounts
TX-602D tracking transmitter with magnet -  top view
Centre loaded antenna
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Items in the bottom case shell
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RX-360 direction finding receiver
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Front panel
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Rear panel
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Readout unit (compass)
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Antenna set with magnet mounts
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TX-602D tracking transmitter with magnet -  top view
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Centre loaded antenna

Compatible transmitters
Bird Dog compatible tracking transmitter (beacon)
TX-610 remote controlled tracking beacon
TX-610
TX-612 remote controlled tracking beacon
TX-612
TX-916 Body Transmitter 1W with scrambler
  1. Note that the remote control features of the TX-610 and TX-612 cannot be controlled from the RX-380XT.

Setup
The diagram below shows the basic setup of the Bird Dog 360XT. At the far left is the target transmitter (beacon) that transmits an intermittend signal. This signal is picked up by four antennas that are switched in quick succession to simulate a rotational movement. The receiver delivers its signal to a controller, which converts it into an Angle of Arrival (AoA), which is then displayed on the external display unit (the compass). More about this under 'operating principle'.



Mobile direction finding
The diagrams below show the position of the four antennas on the roof of the surveillance vehicle. for a proper and homogeneous radiation pattern, the cross should be placed at the centre of the roof, with the arrow pointing in the forward (driving) direction of the vehicle.


The four coaxial cables should be guided through one of the windows into the car, and must be connected to the four antenna inputs (marked 1-4) at the rear panel of the receiver. Each cable is labelled (1-4), and it is important that each antenna is connected to the corresponding input.

Operating principle
The operating principle of the Bird Dog 360XT is currently unknown, but based on the antenna arrangement and the interior of the receiver, it is most likely a Doppler-based direction finder. This means that each of the four antennas is selected in quick succession, in order to simulate a rotating antenna. The pseudo-rotation of the antenna induces a doppler shift in the frequency of the intercepted signal, which can be used to determine the angle of incidence. This angle is then displayed on the external display unit.

 Doppler-based direction finding
 More on direction finding


Parts
Halliburton storage case
Direction finding receiver RX-380XT
Remote display (compass)
4 identical antennas
Window mount for compass
Motion-activated tracking transmitter TX-602D
Beacon antenna
Antenna
12V DC power cable
Power
Storage case
The complete direction finding kit is stowed in a large black plastic Halliburton transit case that measures xxx × xxx × xxx mm and weights xxx kg. The antenna base (i.e. the cross) is stowed inside the case lid, behind the protective foam.

The receiver, the display, the beacon and all other accessories and spares, are stowed in the bottom case shell.
  

Receiver   RX-380XT
At the heart of the direction finding system is the RX-360 receiver shown in the image on the right. It is housed in a large rectangluar enclo­sure which has all controls at the front and all connections at the rear.

For readout of the direction to the target, the external display unit (compass) should be connected at the rear.
  

Display   compass
An external display unit shows the direction to the target. It must be connected at the rear of the receiver and must be mounted near the dashboard, within reach of the driver.

At the right is a circle with LEDs that indicate the angle to the target. At the centre of the circle is a 3-digit display that shows the angle more accurately. At the top left is a 1-digit display that shows the signal strength. The brigthness of the LEDs can be adjusted with the knob at the bottom left.

  

Antennas
For an accurate reading of the angle to the target (the bearing), the system uses four ¼λ antennas, arranged in a square and spaced ¼λ apart. For this, an antenna mount with four strong magnets is stowed in the lid of the transit case. It most be placed at the centre of the rooftop of the surveillance vehicle.

The four antenna rods are stowed at the front of the bottom section of the case.
  

Window mount
A telescopic arm with a large suction cup is provided for mounting the display unit near the dashboard, with the suction cup attached to the front window.

At the other end of the telescopic arm is a tapered plate which mates with a shoe at the rear of the display unit.
  

Transmitter   TX-602D
Although the receiver can be used with virtually any covert transmitter that operates in the same frequency band, it works best with one of the compatible tracking transmitters (beacons) that were available from AID.

It is powered by three 9V alkaline batteries and can be attached to the bottom of a suspect's car (the target vehicle) by means of three magnets.

 More information

  

Beacon antenna
The beacon is supplied with the short unobtru­sive centre-loaded antenna shown in the image on the right. The length of the antenna and the extension coil near the centre are carefully cal­culated to match the transmission frequency of the beacon.

Depending on the application and the situation at the target, other antenna designs were available on request.

  

Power cable
The receiver is designed ot be powered directly from the 12V DC network of a regular car. For use in trucks are large vans, it may be necessary to use a 24/12V DC/DC converter.

For connection to the cigarette light socket that is available in most cars, the power cable shown in the image on the right was supplied.

  

Suitcase with Bird Dog tracking system
Bird Dog 360TX tracking system in suitcase
Items in the bottom case shell
Antenna cross stowed in case lid
RX-360 direction finding receiver
Readout unit (compass) with cable
Readout unit (compass)
Window mount for compass
Four 1/4 Lambda antennas
Antenna cross with magnet mounts
Antenna set with magnet mounts
Antenna mount
Antenna wiring
12V DC power cable
TX-602D tracking transmitter with magnet -  top view
Centre loaded antenna
Antenna
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Suitcase with Bird Dog tracking system
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Bird Dog 360TX tracking system in suitcase
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Items in the bottom case shell
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Antenna cross stowed in case lid
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RX-360 direction finding receiver
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Readout unit (compass) with cable
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Readout unit (compass)
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Window mount for compass
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Four 1/4 Lambda antennas
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Antenna cross with magnet mounts
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Antenna set with magnet mounts
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Antenna mount
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Antenna wiring
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12V DC power cable
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TX-602D tracking transmitter with magnet -  top view
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Centre loaded antenna
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Antenna

Specifications
  • Device
    Radio Direction Finder
  • Purpose
    Vehicle tracking
  • Model
    Bird Dog 360XT
  • Manufacturer
    Audio Intelligence Devices (AID)
  • Years
    1995-2004
  • Receiver
    RX-360
  • Beacon
    TX-602D
  • Frequency
    150-174 MHz 1
  • Channels
    6 2
  • Method
    Crystal-based
  • Spread
    1.5 MHz 2
  • Modulation
    CW/USB, Narrow-band FM
  • Modes
    see below
  • Motion
    Motion tracking only with Bird Dog compatible beacons
  • Power
    12-15V DC
  • Dimensions
    ?
  • Weight
    ?
  1. 136-150 MHz on special order.
  2. All 6 channels are crystal-controlled and must be within a single 1.5 MHz band segment.

Channels
The RX-360 receiver is our collection (S/N 0226002) is populated with the following channels:

  1. Alpha
    164.460 MHz
  2. Bravo
    ?
  3. -
  4. -
  5. -
  6. -
Modes
  • Pulse DF
  • CW DF
  • Voice 1
  • Audible search 1
  1. No direction finding capabilities in this mode.

Checklist
Documentation
  1. Bird Dog 360XT Instruction Manual
    Audio Intelligence Devices. 90035-45. Rev. 3, August 2002.

  2. TX-602D Motion Sensing Tracking Transmitter - Operating Instructions
    Audio Intelligence Devices. 90034-72. Rev. 3, April 2002.

  3. The Use of Cigarette Lighter Receptacles as a Voltage Source...
    Audio Intelligence Devices, Inc. G920807. January 2001.
Further information
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Crypto Museum. Created: Friday 19 January 2024. Last changed: Monday, 22 January 2024 - 13:06 CET.
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