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 ENTER.
2. Scroll through the map datum options until ‘USER’ appears, and press ENTER.
3. Enter values for ‘DX’, ‘DY’, ‘DZ’, ‘DA’, and ‘DF’ using the rocker keypad, and press
ENTER.
4. Highlight ‘SAVE?’, and press ENTER. The setup menu will reappear.
The user datum function is
recommended only for individ-
uals  trained  in  cre a t i n g
map/chart datums. Incorrect
entries may result in substan-
tial position errors.REFERENCEGPS II  7/23/98 4:05 PM  Page 75 
						

							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 unit of measure:
1. Highlight the ‘units’ field (Fig. 76b), and press ENTER.
2. Select the desired unit of measure, and press ENTER.
Fig. 76a
Fig 76bREFERENCEGPS II  7/23/98 4:05 PM  Page 76 
						

							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. Enter the degrees and direction of magnetic variation, and press ENTER.REFERENCE
Fig. 77a
Fig 77bGPS II  7/23/98 4:05 PM  Page 77 
						

							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 logs between two GARMIN GPS devices 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 ENTER.
2. Select a desired setting, and press ENTER.
To disable all interfacing capabilities, select the None/None setting. If you want to
output NMEA 0183 data without any differential input capability, select ‘None/NMEA.’  During data transfer, the num-
ber of packets being exchanged
will be displayed on screen.REFERENCEGPS II  7/23/98 4:05 PM  Page 78 
						

							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 GARMINGBR-21 differential beacon
receiver. Once a RTCM setting has been selected, the GPS II will either automatically
try to tune the last frequency 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.
To enter a DGPS beacon frequency:
1. Highlight the ‘freq’ field (Fig. 79a), and press ENTER.
2. Enter the desired frequency, and press ENTER.
3. Highlight the ‘rate’ field (Fig. 79b), and press ENTER.
4. Select the desired transmission rate, and press ENTER.
Fig. 79a
Fig. 79bREFERENCEGPS II  7/23/98 4:05 PM  Page 79 
						

							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 beacon signal is tuned and no corrections are being received, a ‘no data’
message will be displayed.
•If a beacon signal cannot be tuned, a ‘no status’ message will be displayed.
The GPSII will also display one of three alert messages concerning DGPS opera-
tion through the message page:
No DGPS Position— not enough data is available to compute a DGPS posi-
tion.
No RTCM Input— the beacon receiver is not properly connected or the baud
rates do not match.
RTCM Input Failed— DGPS data was being received but has been lost. The message page will alert
you to any problems relating to
DGPS operation. You may also
monitor the DGPS status from
the status field on the interface
setup page.REFERENCEGPS II  7/23/98 4:05 PM  Page 80 
						

							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 press ENTER.
3. Select ‘Simulator?’ (Fig. 81a), and press ENTER.
Once the simulator mode has been activated, use the position, compass, or high-
way page to set your speed and track. You may also enter a new position if you
desire (only from the position page). 
To enter a track, speed, and position:
1. Highlight the ‘track’ field, and press ENTER.
2. Enter a track heading (Fig. 81b), and press ENTER.
Fig. 81a
Fig. 81bREFERENCEGPS II  7/23/98 4:05 PM  Page 81 
						

							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 rocker keypad.
Fig. 82a
Fig 82bREFERENCE
#!GPS II  7/23/98 4:05 PM  Page 82 
						

							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
counter-clockwise. 
2. Remove used batteries and insert new batteries into position. The battery pole you
can still see should match the symbol marked on the case. 
3. Close and secure the battery cover by turning the thumb loop 1/4  turn clockwise.83APPENDIX AGPS II  7/23/98 4:05 PM  Page 83 
						

							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 desired mounting surface, and press into place. 
4. Place the adhesive side of the smooth piece of Velcro on the
bottom of the unit (between the rubber anti-skid bumps), and
press into place.
5. Mount the unit, placing one piece of Velcro on top of the
other.84APPENDIX BGPS II  7/23/98 4:05 PM  Page 84