About Gps And Gnss - Jensen VM9725BT Operating Instructions Manual

VM9725BT

About GPS and GNSS

The unit uses a vehicle Global Positioning System (GPS)-based navigation device
which uses digital map data to guide you from your selected location A to
location B, using location information obtained from a Global Navigation Satellite
System (GNSS).
A GNSS consists of a set of satellites that transmit high-frequency radio signals
containing time, direction, and distance data that can be picked up by a receiver,
allowing users to pinpoint their precise locations anywhere around the globe.
Navigation Satellite Receivers (GPS devices) use this transmitted information to
calculate an exact location on the Earth. Every point on Earth can be identified
by latitude and longitude. The receiver uses the information sent by at least three
satellites and determines the coordinates of the receiving device.
By comparing the time the signals were transmitted from the satellites and the
time they were recorded, the receiver calculates how far away each satellite is.
The distance of the receiver from three or more satellites reflects its position
on the surface of the planet. Using these distance measurements, the receiver
might also be able to calculate speed, bearing, trip time, distance to destination,
altitude, etc. The GPS position may be displayed as a point on a digital map (at
least three satellites' signals must be received) and as the GPS device moves the
corresponding trace is displayed as well.
Please keep in mind that although the radio signals of navigation satellites will
pass through clouds, glass, plastic, and other lightweight materials, satellite-
navigation receivers will not work underground or in some enclosed spaces.
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