L3 comminications SERIES 5000, Operation And Maintenance Manual

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Different Cable Lengths and the Startup.ini File
D-29
D.6 Different Cable Lengths and the Startup.ini File
The Series 5000 Sonar Systems operate at high data rates. For optimum
performance, settings have been provided to tune the system’s uplink for various
cable lengths up to -24 dB of insertion loss. The adjustment settings are made in
the Startup.ini file using the following two lines:
set PREEMPHISIS x
set LBOGAIN x
This file may be opened in any text editor such as Wordpad. After editing, save the
file.
The adjustment parameters are as follows:
set PREEMPHISIS x x = (0-7) SonarPro Command $ML x
set LBOGAIN x x = (0-3) SonarPro Command $MG x
We recommend the following:
For a 15-meter cable,
set PREEMPHISIS 0
set LBOGAIN 0
For a 150-meter cable,
set PREEMPHISIS 2
set LBOGAIN 1
For cables around 600 meters,
set PREEMPHISIS 4
set LBOGAIN 2
For cables that are longer, experimentation with the above settings should be done.
However, the only sure technique is to connect a counter or oscilloscope to the
BER connector on the Demultiplexer board in the TPU to monitor the bit-error rate
and then vary the uplink parameters until error-free operation is achieved. We
recommend running SonarPro and using the
Towfish Diagnostics tab of the Sonar
Interface dialog box.
For example, when testing a 1000-meter cable, from SonarPro the following
command set yielded error-free operation: $MG2 and $ML4. Therefore the
Startup.ini file would be adjusted to contain the following:
set PREEMPHISIS 4
set LBOGAIN 2