Garmin GPS 12XL - Manual (Page 49)

Interface Setup
The GPS 12XL’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 out-
put 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.’
DGPS Interface
The last two format settings allow the differential-
ready GPS 12XL 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 avail-
able: RTCM/NONE, which allows connection to a bea-
con receiver with no output capability; and
RTCM/NMEA, which allows DGPS input and NMEA
output.
Once a RTCM setting has been selected, the GPS
12XL will either automatically try to tune the last fre-
quency 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.
45
Choose an interface
option based upon what
equipment you are using
to transfer information.
REFERENCE
Interface Setup
& DGPS
Once the RTCM option is
selected the GPS 12XL
will automatically tune
itself or display a default
frequency.
GPS 12XL Manual Rev C 7/10/98 11:19 AM Page 45