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Re: [tracker2] Deluo first startup

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  • Tom Hayward
    Slightly off-topic GPS info for those who are interested: GPS satellites broadcast a 30 day almanac containing information on the locations off all the GPS
    Message 1 of 2 , May 25, 2007
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      Slightly off-topic GPS info for those who are interested:

      GPS satellites broadcast a 30 day almanac containing information on the locations off all the GPS satellites and their trajectories for those next 30 days. Your GPS receiver downloads this almanac when it is powered on. If you don't power on a GPS for 30 days, it won't have a current almanac, and therefore won't know what to look for in the sky. The long acquisition time is the GPS listening to various channels trying to piece together parts of the almanac until it gathers enough data to start predicting satellites' locations, receiving those satellites, then calculating your position based on the received data. The first time a GPS is ever powered on is a similar situation, just with absolutely no information to start guessing with, so it takes a little longer.

      Tom KD7LXL

      On 5/25/07, Tom Tengdin <t3@...> wrote:

      My experience is that the VERY FIRST time you apply power to the Deluo
      it can take
      20 to 30 minutes to get a fix.

      Once you get a fix the first time it powers up and gets locked very quickly.

      I think Scott mentioned testing them before he ships so he might be the one
      who has to wait.

      In brief conversations with local GPS experts they say that 20 or so
      minutes
      for a GPS with no idea where it is and no ephemeris data in memory is
      not an un-reasonable startup.

      T3
      WB9VXY


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