Guralp Systems CMG-DCM build <10,000 - Manual (Page 94)

CMG-EAM (Platinum Firmware)
Next, select the serial port from which you want to input NMEA.
Set the Port function to “NMEA out. NMEA (time + fixed position)
output” and the Port speed to 4800. Click “Submit” to save the
changes.
8.6 Configuring NMEA output
Platinum can generate simulated GPS data (NMEA-0183) to
synchronise a connected digitiser's clock. In this case, the internal
clock of the CMG-EAM is used as a reference for the digitiser. In order
to provide a sufficiently accurate time-stamp, the clock must be
controlled using NTP (See section 6.3 on page 64).
To configure NMEA Output using the web interface, select “Serial
ports” from the “Configuration” “All options” menu
→ or select the
“Serial ports” short-cut from the “Configuration” → “Data
transfer/recording options” menu. To configure NMEA Output from
the command line, start gconfig, select “Serial ports” from the top
level menu.
Next, select the serial port from which you want to output NMEA.
Only one port can be used for NMEA output at any time: the timing
constraints are such that a single processor cannot produce the pulse-
per-second (PPS) signal on two ports simultaneously with sufficient
accuracy.
94 Issue C
Note: For authenticated digitisers, this will be Port C. For more
details of Authenticated Digitisers, please see section 14.2 on
page 190.