Uniden TRAX430 - Manual (Page 74)

Page 74
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Some helpful things to know about the GPS Status screen:
There are a total of 27 GPS satellites in orbit, arranged so that
at least 4 satellites can be seen from every point on the planet at
all times. These satellites broadcast radio signals that allow GPS
devices to find them. Atmospheric conditions and radiation can
affect the signal strength on the satellite’s end just as the local
environment can affect the signal strength on the recevier’s end.
Satellites in view are above the horizon and have the potential
to be tracked. When the device receives a valid, continuing
signal from a satellite, it marks that satellite as tracked. When
the device synchronizes with the satellite and locks onto its
position in the sky, it marks that satellite as active.
The device must lock onto at least three satellites to estimate
your latitude and longitude. If it locks onto four satellites, it can
also calculate your altitude. Generally, the device must lock
onto four satellite signals to calculate your position accurately.
The GPS Status screen also shows the accuracy of your
position. An accuracy of 10 feet means that the calculated
position is within a 10 foot radius of your actual position.
Once the device locks onto the satellites, it can usually maintain
the lock even if the signal strength goes down. Also, if the
device locked onto the satellite signals within the past 30
minutes or so, it can often get a new lock very quickly.
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