L3 Comminications SERIES 5000 Operation And Maintenance Manual - C.6 Towfish Commands

Towfish Commands

C-17

C.6 Towfish Commands

Although sonar control is normally performed using the Ethernet or NMEA 

interfaces, direct control of the towfish is possible. Various parameters of sonar 

operation are performed in the towfish, such as waveform selection, TVG page, 

etc. These parameters are set by transmitting control messages to the towfish via 

the downlink telemetry. The control messages take the form:

$XYd

where X is the destination, Y is the command and dd is the data for the command. 

The destination of the command instructs the downlink processor where to route 

the command as there are multiple possible destinations for a command. For 

example, one can send commands to the on-board compass, the Transmitter PCB, 

the MUX PCB, etc. For the 5000 System the possible destinations are M for the 

MUX PCB, T for the Transmitter PCB and C for the Compass module. For the 

3000 System the possible destinations are M for the MUX PCB, S for the SBP, C 

for the Compass module and A for the auxiliary RS-232 port. For the System 5900 

the possible destinations are M for the MUX board, D for the DSP board, X for 

Transmitter board #1 and Y for Transmitter board #2.

Issuing commands to the towfish can be done in a number of ways. The most 

straightforward technique is to use the towfish command interface in the SonarPro 

software. The desired command is simply entered and then sent to the towfish. 

Another technique is to use the $PKLA,FC command via the NMEA interface 

(COM2). The desired command is simply typed after the ‘FC’. For example, 

$PKLA,FC$MT9. The final technique is to use the towfish diagnostics 

connectors located inside the TPU. On the 5000 System a special cable is needed 

to break out a header on the DEMUX board to a DB-25 connector. This connector 

can then be hooked to a terminal and direct control of the towfish achieved. This is 

normally reserved for factory use. For the 3000 System a terminal can be 

connected to COM3 on the DEMUX board. Once again, this is normally reserved 

for factory use.

C.6.1 5000 System MUX Commands

The following commands are available to control the 5000 System Multiplexer:

$MTd:

Sets the TVG page where d = 0 – F in hexadecimal format. 

The default page is 7. Increasing the value increases the 

gain by 3 dB for each increment. Conversely decreasing this 

value decreases the gain by 3 dB.

NOTE  

The systems are available with a range of pressure sensors. This is 

the reason that absolute depth is not calculated by the TPU.