Originally Posted by JRSCCivic98
aGPS (assisted GPS) is cell tower triangulation.
Wrong. Not correct. AGPS IS NOT ANTENNA TRIANGULATION...
The "a" in A-GPS is Assisted, not Antenna.
aGPS is satellite based, but downloads the ephemeris
(locations of satellites) over the cellular network. Some cheapie GPS chipsets don't know how to calculate the locations of satellite, and need 'help' by downloading the data OTA in order to find the satellites, which are then finally used to pinpoint the location. That's why Verizon charges you. This is different from triangulation.
The antenna can provide other help, such as speed up the calculation of the location of satellites based on the location of the antennas. No location triangulation
is being done with the antennas, the location triangulating is being done with the signals from the satellites themselves. The cell tower antennas are just helping with locating the satellites. (And, sigh, a big excuse for Verizon to charge for the service.)
Too many people confuse GPS
, and antenna-based location triangulation
. These are three separate things
. Even the customer service at many cellphone companies confuse the three, thinking there are only two.
Both GPS and AGPS can be equally accurate, good enough for TeleNav, etc.
Verizon's AGPS can still be very accurate, good enough for TeleNav, etc.
Antenna triangulation is not very accurate (can be 1km off), it's never used for map navigation software.
(Rogers, T-Mobile) Assisted GPS (A-GPS)
(Verizon) Verizon VZ Navigator Ephemeris
(All GPS chips need this)
Makes better sense?