The Global Positioning System (Gps); Understanding The Gps Feature - Motorola APX 4000 User Manual

The Global Positioning System (GPS)

This feature uses information from the Global Positioning
System (GPS) satellites orbiting the Earth to determine the
approximate geographical location of your radio, expressed as
latitude and longitude or MGRS format per request from
customer. The availability and accuracy of this location
information (and the amount of time that it takes to calculate it)
varies depending on the environment in which you are using the
GPS feature.
For example, GPS location fixes are very difficult to obtain
indoors, in covered locations, between high buildings, or in
situations where you have not established a clear broad view of
the sky.
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Understanding the GPS Feature

The GPS technology uses radio signals from earth orbiting
satellites, to establish the location coordinates, maximizing your
view of clear unobstructed sky is essential for optimum
performance.
Where adequate signals from multiple satellites are not
available (usually because you cannot establish a view of a
wide area of the sky), the GPS feature of your radio will not
work. Such situations include but are not limited to:
•
Underground locations
•
Inside of buildings, trains, or other covered vehicles
•
Under any other metal or concrete roof or structure
•
Between tall buildings or under dense tree-cover
•
In temperature extremes outside the operating limits of your
radio
Even where location information can be calculated in such
situations, it may take longer to do so, and your location
estimate may not be as accurate. Therefore, in any emergency
situation, always report your location to your dispatcher.
Note: Even where adequate signals from multiple satellites
are available, your GPS feature only provides an
approximate location, usually within 20 meters from
your actual location, but sometimes further away.
Keep in mind that the accuracy of the location information and
the time it takes to obtain it varies depending upon
circumstances, particularly the ability to receive signals from an
adequate number of satellites.
Note: The satellites used by the GPS feature are controlled
by the U.S. government and are subject to changes
implemented in accordance with the Department of
Defense GPS user policy and the Federal Radio
Navigation Plan. These changes may affect the
performance of the GPS feature on your radio.
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