GAPS - User Guide
9.4 Recovering the Equipment
9.4.1 RECOVERING GAPS
1. Click on the Stop Tracking button.
2. Recover GAPS unit.
3. Rinse GAPS unit with fresh water.
4. Fasten the hydrophone caps back in place.
9.4.2 RECOVERING TRANSPONDERS WITH THE TELECOMMAND
The moored transponders are recovered with the remote control function in the
TELECOMMAND menu. iXblue TT801 remote control also performs this task.
The remote control transmits a signal to the transponders. Once the signal received by the
transponder, the transponder answers by an acknowledgment signal (CAF). The hook engine
rotates, freeing the release ring and the weight. Another acknowledgment signal is transmitted
by the transponder after the complete rotation of the engine. The transponder goes up towards
the surface carried by the buoys at the speed of approximately 1 to 2 m/s. Once at the surface,
the transponders are ready for recovery.
Click on the Stop tracking button before any recovery operation. The USBL antenna must not
be pinging while the remote control is operating.
GAPS sends commands to the transponders. Commands are configured by the input of the
following parameters:
● Bit0 and Bit1: two frequencies defining the 0 and 1 values of the coded signals
● CAF: acknowledgment signal send by the transponder
● ARM: hexadecimal value of the arming command that wakes the transponder up
● CMD: hexadecimal value of the command
● Acknowledgment Timeout: from 1 to 60 s in which the device waits for an
acknowledgment signal of the command from the transponder
Transponder
Label
Command codes can be found on the manufacturer label stuck on the transponder. These
codes are in hexadecimal format. Table below links hexadecimal values to code numbers.
Table 15 - Correspondence between frequencies and hexadecimal codes
Code 0 1 2 3 4 5 6 7 8 9 A B C D E F
kHz 19.5 20 20.5 21 21.5 22 22.5 23 23.5 24 24.5 25 25.5 26 26.5 27
Decoding the transponder build sheet:
The frequency FR0 (19.5 kHz) in first column corresponds to code 0.
The frequency FR1 (20.5 kHz) in first column corresponds to code 2.
ARM/RANGING (0251), made of 0 (FR0), 2 (FR1) and 51, is the arming code.
154 MU-GAPS-AN-005-H - November 2019
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