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PR Newswire
15-10-2012, 12:52 PM
ＡＧＰＳ is simply used to quick start the GPS to first fix by providing GPS with current location， ＵＴＣ time and probably supplying almanac and ephemeris data to the onboard gps.
With the information, GPS will be able to determine the satellites and their IDs that are currently in view with the GPS in open space.
It assists the GPS to quick start. If the GPS satellites are not present, it cannot do anything.
Normally, GPS downloads almanac and ephemeris through GPS satellites but the GPS bit rate is low and coupled with the need to lock-on to GPS signals, GPS initialization will take a long time.
Nowsaday, GPS receivers come with 12 or more channels(24?) and the lock-on time has already been reduced.
But, the communication bit rate is still too low and so for a cold start, 45 sec is probably the minimum.
With the information, GPS will be able to determine the satellites and their IDs that are currently in view with the GPS in open space.
It assists the GPS to quick start. If the GPS satellites are not present, it cannot do anything.
Normally, GPS downloads almanac and ephemeris through GPS satellites but the GPS bit rate is low and coupled with the need to lock-on to GPS signals, GPS initialization will take a long time.
Nowsaday, GPS receivers come with 12 or more channels(24?) and the lock-on time has already been reduced.
But, the communication bit rate is still too low and so for a cold start, 45 sec is probably the minimum.