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  1.    #1  
    It is known that the Treo (or any phone that claims to have GPS capabilities) has GPS capabilities for the purpose of e911. Do these phones use GPS or Triangulation? When I think of GPS, satellites come to mind. I am pretty sure that Treos are not accessing satellites for location information. So, does the Treo use triangulation instead of GPS? Any supporting websites would be great; I have a wager with a co-worker.

    Thanks in advance.
  2. #2  
    Triangulation.. It's not GPS, it's AGPS, which is assisted GPS.

    There's no GPS chip in the phone, the towers do all the calculations. And it's much less accurate than real GPS.

    Google is a great supporting website
  3.    #3  
    Thanks for you help.

    Google.......um......never heard of it......
  4. #4  
    My understanding is that telephones that have AGPS do indeed have simplified GPS chipsets in them. They get the assist from cell phone network that provides approximate location so that the GPS can lock on much more quickly. You may have noticed that when you cold start a GPS it can take up to several mins. to aquire the sats and provide a fix, whereas if you warm start it, a fix takes only a few seconds. So, as I understand it, many cell phones have AGPS with a bona fide GPS receiver. Others use base-station based multilateration (based on time delay) and don't have GPS receivers at all.

    -Phil
  5. #5  
    GPS = GLOBAL position system. satellites. There are some with real GPS in them, the rest are triangulation on the tower-side and not available to the handset unless routed back to it.

    From what I understand only a handful of Nextels have real GPS in them.

    And the reason it takes longer to cold start than warm start a GPS is because the GPS has an idea of where the satellites are and if it's wrong it has to wait for quite some time to get a fix on enough to get a good location. This takes especially long if you're moving or it doesn't have a clear view of the sky and therefore less satellites to see. If it's a warm start, it knows where the satellites are and only takes a short period to adjust itself.

    Not sure what all that has to do with cellular AGPS, but anyway..
  6. #6  
    Bob Meyer
    I'm out of my mind. But feel free to leave a message.

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