Garmin GPS 75 - Manual (Page 50)

6-8
To change the pre-defined datum...
· Highlight the “Change?” field and press ENT.
· With the arrow keys, find the desired datum and highlight it.
· Press ENT. The new datum is selected
The user-defined datum option allows
you to custom-tailor a datum reference
from which all position coordinates are
calculated. All entries are defined as
differences from the WGS 84 standard
datum. CAUTION: Selection and use of
the user datum function is for individuals
experienced in the use of map datums. If
the pre-defined map datums do not
correspond to the chart you are using and you are unsure of the correct
entries required to correspond to that chart, contact the chart
manufacturer. Incorrect entries for a user-defined datum may result in
substantial position errors.
6.9BEACON RECEIVER SETUP
The Beacon Receiver Setup Page allows
you to control a GARMIN Beacon
Receiver for Differential GPS (DGPS)
position corrections. Before the beacon
receiver can be controlled by the GPS 75,
it must be connected to the I/O port on
the back of the unit and the “RTCM/
NMEA 0183” mode must be selected on
the Interface Setup Page. If this interface
mode is not selected, the GPS 75 will only display the message “No
RTCM/NMEA 0183 interface selected” on the Beacon Receiver Setup
Page. Once the correct interface is chosen, the Beacon Receiver Setup
Page will display as shown above.
The “Tuned To:” field is the frequency in kHz to which the beacon
receiver is currently tuned or is attempting to tune. Below this field is
a bit rate cyclic field which allows you to choose between bit rates of 25,
50, 100, and 200 bps by pressing the “CLR” key which the “Bit Rate” field
is highlighted. When you first select the Beacon Receiver Setup Page
from the Auxiliary Menu, (after selecting an RTCM/NMEA 0183 input/
output interface mode), the GPS 75 will automatically try to tune the last