How to track an underwater locator beacon

Historically, Sonardyne supplied AODC beacons, such as the Type 7097 and 7192.

However, these are now obsolete, and Technical Bulletin, TB21-001 recommends the 3^rd party RJE ATT400 Emergency Beacon.

This article describes how to track Underwater Locator Beacons (ULBs) like these.

Traditionally, an AODC Transponder is configured for either Channel A or Channel B.

Sonardyne’s now-obsolete AODC beacons utilised the following specifications:

Note that the only difference between Channel A and B, is the interrogation frequency.

This can be tracked from Marksman/Ranger 2 by selecting an AODC beacon.

Select either Channel A or B.

Track the beacon as normal.

Although the summary data sheet of the AT400 suggests that the beacon supports AODC Channels A & B described above, its datasheet suggests otherwise.

The configuration is selected by opening the beacon, and accessing SW1 as shown below.

Assume the beacon is set as a free-running Pinger, to transmit pulses of 33 kHz at regular intervals when its water-activated switch is enabled.

Access the Pinger Locator.

Enter the expected Pinger frequency, and assumed beacon depth below the transceiver face, and click Apply.

The beacon’s position will be displayed, together with its elevation, and received signal strength and SNR.

Adjust the Transceiver Gain accordingly.