Garmin GPS 48 Owner's Manual - Page 56

REFERENCE Interface Setup Choose an interface option based upon what equipment you are using to transfer information. Once the RTCM option is selected the GPS 48 will automatically tune itself or display a default frequency. 52 Interface Setup The GPS 48's interface page lets you specify the formats for connecting external devices. There are six options: GRMN/GRMN, None/None, RTCM/None, RTCM/NMEA, NMEA/NMEA, and None/NMEA. Each option lists the input format first, followed by the output format. To select I/O format: 1. Highlight the I/O field, and press E. 2. Select the desired setting, and press E. The GRMN/GRMN setting is a proprietary format that lets you exchange information such as waypoints, routes, and track logs between two GARMIN GPS units or a GARMIN GPS and a PC. There are eight data transfer options: send alm, send wpt, send trk, send rte, request alm, request wpt, request trk, request rte. To select a transfer option: 1. Highlight 'HOST', and press E. 2. Select a desired setting, and press E. To disable all interfacing capabilities, select the None/None setting. If you want to output NMEA data without any differential input capability, select 'None/NMEA. Once a NMEA output setting has been selected, the NMEA field will become highlighted. NMEA formats 0180, 0183 or 0183 (1.5 or 2.0) are available. The data transfer rate can be set to 130, 300, 600, 1200, 2400, 4800 or 9600 baud. DGPS Interface The last two format settings allow the differentialready GPS 48 to accept RTCM DGPS corrections in RTCM 104 version 2.0 format. Using DGPS corrections will improve receiver accuracy to 1-5 meters, regardless of errors induced by the government's Selective Availability (SA) program. Two RTCM options are available: RTCM/NONE, which allows connection to a beacon receiver with no output capability; and RTCM/NMEA, which allows DGPS input and NMEA output. Once a RTCM setting has been selected, the GPS 48 will either automatically try to tune the last frequency and bit rate you selected or will switch to the default frequency of 304.0 kHz with a bit rate of 100 bps if no previous beacon has been tuned. You may also enter your own frequency and bit rate if desired.