Lowrance lms-522c igps 操作ガイド

161 

Map Overlays (Range Rings; Lat/Long Grid) 
The map screen can be customized with four range rings and/or grids 

that divide the plotter into equal segments of latitude and longitude. 
Range rings are handy for visually estimating distances on the map. The 

ring diameters are based on the current zoom range. For example: at the 

100 mile zoom, the screen will show two rings with your current position 

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 turn on/off range rings:  
1. From the Map Page, press 

|

↓ to 

|

.  

2. Press 

↓, → to 

. With the option highlighted, press 

 to 

check it (turn on) and uncheck it (turn off.)  
3. After the option is set, press 

|

 to return to the page display. 

To turn on/off Lat/Long Grid lines: 
1. From the Map Page, press 

|

↓ to 

|

.  

2. Press 

↓, to 

. With the option highlighted, press 

 

to check it (turn on) and uncheck it (turn off.)  
3. After the option is set, press 

|

 to return to the page display. 

Maps and charts are based on a survey of an area covered by the map 

or chart. These surveys are called Datums. Maps using different da-

tums will show the same latitude/longitude in 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 unit uses the 

WGS-84 datum. It, however, can show your position using any of 191 

datums. Different datums can be selected. To change the datum: 
1. Press 

|

|

↓ to 

|

|

↓ to 

|

. 

2. Use 

↓ ↑ to select the desired datum, then press 

. 

3. To return to the last page displayed, press 

|

. 

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