6-7
output is selected, a second cyclic field appears. From this second field,
you may select the desired NMEA format: NMEA 0180, NMEA 0182 or
NMEA 0183.
A second cyclic field also appears when the GARMIN input/output is
selected. The GARMIN option allows you to exchange data such as
waypoints, routes, track logs and satellite almanac data with another
GPS 75 or with a PC-compatible computer. You may select between
acting as a HOST to data exchanges, REQUESTing data, or SENDing
data by highlighting the cyclic field and pressing CLR. When the HOST
option is selected, all interface operations are controlled by another GPS
75 or PC-compatible computer. When the REQUEST or SEND options
are selected, the GPS 75 will control the data exchange. With the
REQUEST or SEND options, a third cyclic field appears where you may
define the type of data to be exchanged: routes, track log, waypoints,
almanac, or proximity waypoints. Select the desired type of data by
highlighting this field and pressing CLR. Press ENT to begin the data
transfer. During the data transfer process, the number of data packets
being exchanged will be displayed. Note: When exchanging data
between two GPS 75s, one should be set to HOST and the second should
be set to the desired data transfer option (REQUEST or SEND).
The GPS 75 can use Differential GPS (DGPS) corrections in RTCM SC-
104 version 2.0 format. DGPS corrections in this format can be received
from an external device (capable of output in 6 of 8 byte format as
specified by RTCM SC-104, version 2.0) by connecting the device to the
input port on the back of the GPS 75 and selecting an RTCM input
interface mode. Two RTCM input modes are available, one which allows
no output and another which allows NMEA output in 0180, 0182, or 0183
format.
6.8MAP DATUM SELECTION
Select the desired map datum
reference from the Map Datum Page.
You may choose from 102 pre-defined
map datums, or you may define your
own. If the map/chart you are using
specifies a reference datum, select
that datum on your GPS 75. If the
map/chart does not specify a
reference datum, you may select each datum applicable to your region
until you find the datum that provides the best positioning at a known
point. NOTE: The GPS 75 is shipped from the factory with the WGS 84
datum selected.