When the unit is receiving a DGPS signal, the Signal to Noise Ratio)(SNR) and Distance fields show data. The SNR range is 0 dB to 30dB, with 30 being the best. The Distance field may or may not showdata, depending on the signal being broadcast from the DGPS site.The DGPS beacon transmitters are operated by the United StatesCoast Guard (or similar government agency in other countries),which is responsible for their accuracy and maintenance. For DGPStransmitter problems or to find the most updated list of frequenciesand coverage areas, contact your local USCG or see their Web site athttp://www.navcen.uscg.mil/.Advanced NMEA Output SetupIf you are going to interface the GPSMAP 276C with anotherpiece of equipment (such as a radar or autopilot), the unit needsto be set to output NMEA data. The NMEA data transmission canbe customized to keep the output rate at two seconds. If too manyNMEA sentences are activated, the unit may take longer than twoseconds to update. You can also set the Output Rate to Fast to outputa minimum number of NMEA sentences at one-second intervals.To access the Advanced NMEA Output Setup:1. Press MENU twice to open the Main Menu, and then selectthe Setup tab.2. Select the COM 1 or COM 2 sub tab.3. Highlight the Serial Data Format field, and press ENTER.4. Select NMEA In/NMEA Out, and press ENTER.5. Press MENU to open the options menu. Select AdvancedNMEA Setup, and press ENTER.Advanced NMEA Output SetupUse the Advanced NMEA Output Setup Page to set the output rate,change the precision of the Lat/Lon minutes, set Waypoint IDs tonames or numbers, and turn on and off the GPS status, the GARMINProprietary sentences, and Waypoint/Route (WPL, RTE).GPSMAP 276C NMEA Sentence Output (NMEA version 3.01compliant):• Always transmitted: GPRMC, GPGGA, GPGLL, GPBWC,GPVTG, GPXTE, GPRMB• Switchable sentences: GPGSA, GPGSV, GPWPL, GPRTE• GARMIN proprietary: PGRME, PGRMZ, PGRMM88 GPSMAP 276C Owner’s ManualM AIN MENU > SETUP TAB
