Garmin GPS 2 Manual

75Map Datums
The ‘map datum’ field is located just below the ‘position format’ field, and comes
with a WGS 84 default setting. Although 106 total map datums are available for use
(see Appendix F for map datums), you should only change the datum if you are
using maps or charts that specify a different datum than WGS 84.
To select a map datum:
1. Highlight the ‘datum’ field, and press ENTER.
2. Select the desired setting, and press ENTER.
To define a user datum:
1. Highlight the ‘datum” field, and press...

76CDIScale Settings
The course deviation indicator (CDI) scale definition field lets you select the +/-
range of the CDI bar scale. Three scales are available: +/- 0.25 (default), 1.25, and
5.0 miles or kilometers.
To enter a CDI scale setting:
1. Highlight the ‘cdiscale’ field (Fig. 76a), and press ENTER.
2. Select the desired setting, and press ENTER.
Units of Measure
The GPS II lets you select nautical (default), statute, or metric units of measure
for all ‘speed’ and ‘distance’ fields.
To change the...

77Magnetic Heading Reference
The GPS II’s heading information can be displayed referencing magnetic north
(auto or user-defined), true north, or calculated grid headings. The default setting is
automatic magnetic north, which is suitable for most applications.
To select a heading reference:
1. Highlight the ‘heading’ field (Fig. 77a), and press ENTER.
2. Select the desired heading preference, and press ENTER.
To enter a user-defined magnetic heading:
.1. Select ‘User Mag’ and press ENTER (Fig. 77b).
2....

78Interface Setup
The GPS II’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 ENTER.
2. Select the desired setting, and press ENTER.
The GRMN/GRMN setting is a proprietary format that lets you exchange informa-
tion such as waypoints, routes, and track...

79DGPSInterface
The last two format settings allow the differential-ready GPS II 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 gov-
ernment’s Selective Availability (SA) program. The RTCM/NONE format will allow
connection to any manually-tuned beacon receiver by using the proper output inter-
face. The baud rate is selectable from the GPS II.
The RTCM/NMEA selection controls the...

80When the GPS II is receiving DGPS corrections from the GBR-21, the ‘beacon
receiver’ section of the I/O setup page will display the beacon frequency and signal
strength, as well as the distance from the transmitter to the beacon receiver. At the
bottom of the beacon receiver field, a status message will keep you informed of
DGPS activity:
•A ‘tuning’ message will be displayed while a beacon signal is being tuned.
•Once the beacon signal has been tuned, a ‘receiving’ message will be displayed.
•If a...

81Navigation Simulator
The GPS II’s simulator mode lets you practice all aspects of its operation without
active satellite acquisition. You can plan and practice trips, enter new waypoints and
routes, and save them for use during normal operation. The simulator is activated
from the system setup page, with speed and heading controlled from the position,
compass or highway pages.
To activate the simulator:
1. From the menu page, highlight ‘SYSTEMSETUP’, and press ENTER.
2. Highlight the ‘mode’ field, and...

823. Highlight the ‘speed’ field, and press ENTER.
4. Enter a speed, and press ENTER.
5. Highlight the ‘position’ field, and press ENTER (Fig. 82a).
6. Enter a position, and press ENTER.
The GPS II does not track satellites in simulator mode. Although you can
create and save waypoints and routes while using the simulator mode,
never attempt to use the simulator mode for actual navigation.
To reset the altitude:
1. Highlight the ‘altitude’ field, and press ENTER (Fig. 82b).
2. Press the left side of the...

Battery Replacement
The GPS II requires 4 AA alkaline batteries. These batteries will need to be
replaced after up to 15 hours of operation in normal mode or 20 hours of operation
in battery-saver mode. Rechargeable Ni-cad or lithium batteries may also be used.
Note: The battery level indicator is calibrated for alkaline batteries, and will be
inaccurate if Ni-Cad or lithium batteries are used.
To replace batteries:
1. Remove the battery cover by turning the thumb loop at the side of the unit 1/4 turn...

Dashboard Mounting
The GPS II can be mounted on the dashboard of an automobile or to another convenient surface using the two
Velcro™ strips provided with the unit. 
To mount the GPS II using the Velcro strips:
1. Select a location for the unit that provides a clear and unob-
structed view of the sky.
2. Remove the paper strip liners from both pieces of Velcro.
3. Make sure the surface to which you’re adhering the Velcro is
clean and dry. Place the adhesive side of the rough piece of
Velcro on the...