L3 Comminications SERIES 5000 Operation And Maintenance Manual - 4.27 Notes On Time Usage
Notes on Time Usage
4-83
Click
Run Compass Calibration Wizard
to open the Compass Calibration Wizard
dialog box which is shown in Figure 4-18 on page 4-14. This provides a fairly
quick and accurate method for calibrating the towfish compass. (See page 4-14 for
instructions on how to use the Compass Calibration Wizard.)
The Series 3000 towfish uses a different pressure sensor than the Series 5000
towfish. If your towfish is equipped with a pressure sensor for towfish depth
readings, choose Sensor from the Window menu to open the Sensor window, and
then right-click in the window to open the Sensor Configuration dialog box shown
in Figure 4-61 on page 4-47. Select the correct pressure sensor scale option. For
the Series 3000,
1500 psia
is the default selection, and
300 psia
is the optional
selection.
4.27 Notes on Time Usage
4.27.1 TPU Time in SonarPro
When using SonarPro, a date and time is displayed in the Information window.
This time is also in the header in the .sdf data that comes from the TPU. The time
is set when SonarPro is started on the master computer.
When the system is successfully booted, SonarPro can be started from the master
computer. The master computer controls the range, pulse width, etc. of the sonar,
and only one master computer can be running at a time with one sonar. Any other
computers connected to the Ethernet Hub and running SonarPro, would be
considered slaves. The slave computers running SonarPro have no control of the
sonar or the TPU.
When SonarPro starts on the master computer, a message is sent to the TPU to set
the TPU clock. The TPU in turn looks at the GPS navigation input on COM2. If it
sees an RMC sentence on COM2 in the GPS message, the TPU clock is set to the
GPS time which is Zulu time. If an RMC message is not seen on COM2, the TPU
sets its clock to the master computer’s clock.
The TPU clock is set whenever SonarPro is started from the master computer.
Thereafter it keeps its own time, either GPS or master computer time. Therefore if
the navigation input is not present when SonarPro is started on the master
computer, and the navigation input is connected after SonarPro is started, the TPU
will not follow GPS time. SonarPro will have to be restarted, or a new state will
have to be initialized to sync the TPU to the GPS time with the RMC sentence
present.