Eagle Electronics 480 Map Datum Selection

in the center. The large ring touching the left and right sides of the

screen is 100 miles in diameter (same as the zoom range). The second

smaller ring is 50 miles in diameter (always 1/2 the zoom range).

The distance from your current position to the smaller ring (the ring's

radius) is 25 miles (always 1/4 the zoom range). With the arrow keys

and map cursor, you can scroll the map to see the third and fourth

rings. In this example, the distance to the third ring is 75 miles and

distance to the fourth ring is 100 miles from your current position.

To set range rings: From the Map Page, press MENU|↓ to MAP

DATA|ENT. Press ↓ to DRAW MAP BOUNDARIES|→ to RANGE RINGS. With the

option highlighted, press ENT to check it (turn on) and uncheck it (turn

off.) After the option is set, press EXIT|EXIT to return to the page display.

To set Lat/Long Grid: From the Map Page, press MENU|↓ to MAP

DATA|ENT. Press ↓ to POPUP MAP INFORMATION|→ to LAT/LON GRID LINES.

With the option highlighted, press ENT to check it (turn on) and un-

check it (turn off.) After the option is set, press EXIT|EXIT to return to

the page display.

Map Datum Selection

Maps and charts are based on a survey of the area that's covered by the

map or chart. These surveys are called "Datums." Maps that are cre-

ated using different datums will show the same latitude/longitude in

slightly different locations.

All datums are named. The GPS system is based on the WGS-84 da-

tum, which covers the entire world. Other datums may also cover the

entire world, or just a small portion of it. By default, your position

shows using the WGS-84 datum. However, it can show your position

using one of 191 different datums. Different datums can be selected; to

change the datum:

2. Scroll ↓ or ↑ to select the desired datum, then press ENT.

3. To return to the last page displayed, press EXIT|EXIT.

a list of the datums used by this unit is in the back of this manual.