The standard time message is a NMEA sentence identified as $GPZDA and is expected to arrive after
the PPS. The time message will also, usually, go to the data collection computer, so the ZDA message
must either be split or output on two of the GPS receiver’s RS-232 ports.
4.1.4.2 Trimble UTC: UTC yy.mm.dd hh:mm:ss ab<CR><LF>"
Trimble GPS receivers provide the PPS time synchronisation message with an ASCII UTC string and
not the ZDA string. The SIM expects the UTC to arrive 0.5 seconds before the PPS. When interfacing
a Trimble GPS, use the UTC message and not the ZDA for timing information. If both the ZDA and
UTC are input, the UTC will take priority; the SIM will automatically ignore ZDA while receiving UTC.
The UTC status code (‘ab’) is ignored.
Setting up the time synchronisation is done through the Sonic Control software detailed in
Section
5.4.
In that each of the SIM serial ports provides 12VDC on selected pins, it is not recommended to use a
fully wired serial interface cable as this may cause some GPS receivers to stop sending data. Use a
cable with only pins 2, 3 and 5 wired, if possible.
4.1.5 Motion Input
The roll component, of the motion data, is used for roll stabilisation. Supported formats and
connection are:
• TSS1 Serial
• IXSea TAH Serial or Ethernet UDP ($PHOCT)
It is recommended to set the motion sensor to output the highest baud rate and highest update rate
possible, preferably 100 Hz or higher.
Connect the motion data to the DB-9 labelled Motion, on the SIM, or via Ethernet input to one of
the RJ45 AUX receptacles. Setting up the serial port or Ethernet parameters is done through Sonic
Control, which is covered in Section 5.4.
4.1.6 SVP input
4.1.6.1 Connecting the sound velocity probe
The sound velocity probe is used to provide the sound velocity at the sonar head, which is used for
the receive beam steering. It is not used for refraction correction; that must be accomplished in the
data collection software employing a full water depth sound velocity cast.
4.1.6.2 Valeport miniSVS
The miniSVS comes with a 15 metre cable. The cable carries both the DC power (8 – 29V DC) to the
probe and the data from the probe to the SIM. The miniSVS is set for a baud rate of 9600 and will
start outputting sound velocity (Format: <sp> xxxx.xxx m/sec) as soon as power is applied. The
miniSVS cable is terminated with a female DB-9 RS-232 connector; this is attached to the male DB-9
Page 39 of 210
Version 5.0 Rev r002
Date 05-08-2014
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