Glossary - Eclipse AVN76D Owner's Manual

Reference

Glossary

Please read the descriptions for following terms to enjoy more.
● GPS (Global Positioning System)
● Wide area map, detailed map
● Measurement
● 2 dimensional measurement and 3 dimensional
measurement
Signals do
not intercross
at one point
Position determined by
2-dimensional measurement
211
GPS is a system to detect current location (latitude,
longitude, altitude) by receiving radiowaves from
normally 4 or more, or 3 in some cases, GPS
satellites orbiting 21,000 km over the Earth.
These satellites are launched and managed by the
US Department of Defense mainly for military use, but
are also open for private usage. This unit performs
navigation using the GPS information, various
sensors, and road map data.
Wide area map is a map with wide area, and detailed
map is a map of small area. The scales of a map are
1/20,480,000, 1/10,200,000, 1/5,120,000, 1/
2,560,000, 1/1,280,000, 1/640,000, 1/320,000, 1/
160,000, 1/80,000, 1/40,000, 1/20,000, 1/10,000, and
1/5,000.
GPS position quality is displayed at left lower.The
more bars light, the more extreme precision GPS
position quality is.
GPS calculates the position using the triangulation.
Distance to the satellite can be determined when the
radiowave from that satellite is received, and current
location can be measured by receiving radiowave
from 3 satellites.
Actual
However, since there are margin of error in the GPS
position
satellites and navigation unit, only 2 dimensional
measurement of latitude and longitude is performed
when radiowave from only 3 satellites are received.
The precision will be lower in this case.
The measurement will be taken in 3 dimensions of
latitude, longitude, and altitude when radiowave from
Error
4 or more GPS satellites are received. 3 dimensional
measurement has higher precision than 2
dimensional measurement, and error of vehicle
location becomes smaller.
211