Garmin GPS 38 - Manual (Page 55)

Interface Setup
The GPS 38’s interface setup page lets you specify the
interfacing formats for connecting external devices. There
are five interface options: GRMN/GRMN, None/None,
None/NMEA, RTCM/None, and RTCM/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 devices or a PC.
During data transfer, the number of packets being
exchanged will be displayed on screen.
To select a transfer option:
1. Highlight the ‘Host’ field and press E .
2. Select a setting and press E .
To disable all interfacing capabilities, select the
None/None setting. If you want to output NMEA data to
compatible external devices without any differential input
capability, select the None/NMEA setting. Once a NMEA
output setting has been selected (with or without RTCM
input), the NMEA field will become highlighted. NMEA
formats 0180, 0182 or 0183 (1.5 or 2.0) are available.
To select a NMEA format:
1. Press E to begin a NMEA selection.
2. Select a format and press E .
DGPS Interface
The last two format settings allow the differential-ready
GPS 38 to accept RTCM DGPS corrections in RTCM 104
version 2.0 format. Using DGPS corrections will improve
receiver accuracy to 5-10 meters, regardless of errors
induced by the government’s Selective Availability (SA) pro-
gram. The RTCM/NONE format will allow connection to
any manually tuned beacon receiver with the proper output
interface, with the baud rate selectable from the GPS 38.
Interface Setup Page
The default interface setting
is the GARMIN/GARMIN
option, which can be used
for unit-to-unit data trans-
fer or interfacing with a
GARMINPCKit.
NMEAInterface
Once a NMEA format is
selected, the baud rate will
automatically be set to the
proper speed. See Appendix
C for a list of NMEA
sentences.
R E F E R E N C E
Interface Setup
& DGPS Setup
51
GPS 38 Man Rev B 7/23/98 4:34 PM Page 51