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9175Re: [tracker2] Re: How to deal with GPS drift with OT2?

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  • James Ewen
    Nov 2 8:29 AM
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      On Mon, Nov 2, 2009 at 1:43 AM, ki6tsf <ki6tsf@...> wrote:

      > I posted a pict showing GPS drift at http://groups.yahoo.com/group
      > /tracker2/photos/album/411553253/pic/812065518/view?picmode=
      > That's not very nice for a portable or mobile digipeater.

      Take a look at your surroundings... If you park the car nose in,
      you've got a wall and car port with a roof that looks to be at least 9
      feet high right in front of the car. Behind you is a 3 storey
      building, maybe 30 feet away. At least you didn't park under the tree.
      (Gotta love Google Streetview!)

      You'll have blocked views of the horizon for most of the azimuth
      around you. The 3 storey wall behind you will probably bounce signals
      like crazy, leading to position accuracy problems with the GPS.

      If you put a relay in the data line between the GPS and the OT2,
      triggered by the accessory line in the vehicle, you will basically
      disconnect the GPS from the OT2. Configure the OT2 to use the last
      known position. Leave the GPS power on constant 12 volts, and the GPS
      will always be active, leading to faster position acquisition when you
      start the vehicle. (By faster, I mean instantaneous, unless you have
      parked in an underground or covered parking area)

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