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Old 12-14-2009, 09:58 PM   #3 (permalink)
F5fstop
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Join Date: Oct 2009
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My BB locks on in a minute or two, inside a ranch style house with no problems.

Also, ephemeris data is transmitted by each satellite, and is not dependent upon being hooked up to a phone company, as long as the GPS in the phone is programmed to allow GPS. It is not transmitted by the phone company since it is satellite dependent. In other words, it is transmitted by GPS satellites.

When the phone's GPS is activated, the GPS chip will receive Almanac information which is sent by all the satellites and gives a rough idea where all the sats are located. This information is valid for a few months.

Next the GPS receiver will receive the ephemeis data from the sats it has locked onto. This data is very precise with actual orbit and clock data from each satellite. In other words, the ephemeris data for a particular sat is sent only from that particular sat. Ephemeris data is valid for only 30 minutes.

That's why there is a warm and a cold turn on for GPS devices. Cold (longer boot up) meaning ephemeris data outdated, warm (faster boot up) meaning ephemeris data is still current.
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