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Reference
Main Menu: Comm Tab
The “Status” fi eld will show one of the following:
• Tuning – unit is attempting to tune to the specifi ed frequency and bit rate.
• Scanning – unit is automatically scanning through the frequencies and bit rates.
• Receiving – unit is receiving DGPS signal and ready for operation.
• Check Wiring – unit is not making connection with DGPS receiver.
When the unit is receiving a DGPS signal, the “SNR” (Signal to Noise Ratio) and “Distance” fi elds
will show data. The SNR range is 0dB to 30dB, with 30 being the best. The Distance may or may not
show data, depending upon the signal being broadcast from the DGPS site.
The DGPS beacon transmitters are operated by the U.S. Coast Guard (or similar government
agency in other countries), which is responsible for their accuracy and maintenance. For DGPS trans-
mitter problems or to fi nd the most updated list of frequencies and coverage areas, contact your local
USCG, or see their web site at http://www.navcen.uscg.mil/.
NMEA Interface
If you are going to interface the GPSMAP 188/188C/238 Sounder with another piece of equipment
(such as a radio or autopilot), the unit needs to be set to output NMEA data. More information on
wiring and NMEA data may be found on page 95.
To activate the NMEA data:
1. On either port of the Comm Tab, highlight the ‘Serial Data Format’ fi eld and press ENTER.
2. Select ‘NMEA In/NMEA Out’ and press ENTER.
Activating NMEA data
188188C238 Manual Part 2.indd 89 6/30/2003, 3:32:34 PM