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Thread: Gps

  1. #1
    Join Date
    Jan 2006
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    Hebrides
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    3,208

    Question Gps

    I have noticed a few posts have included reference to gps.

    How do you find the accuracy of your trip records?

    I have found on mine (Garmin Vista C) that the trip odometer gives a distance that is sometimes quite different from the track log when I have downloaded the track onto my Anquet Map on my pc. On one trip it was about 40% different and overestimated. It was disappointing to find I hadn't paddled quite so far when I had got home.

    I think the difference has something to do with the way the two different records are kept but I am not sure. Anyone have any ideas?

    Cheers
    Q

  2. #2
    Join Date
    Dec 2005
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    ~Kirkintolloch, Glasgow
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    Default

    My quess is that internally it tracks your progress meter by meter and includes every little wiggle (even the GPS noise), while the anquet map just joins major waypoints so is far more direct.
    a 40% error is equivalent to going from 0,0 to 1,1 then 2,0 being recorded as a direct journey 0,0 to 2,0.

    Philip

  3. #3
    Join Date
    Jan 2006
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    Default

    Cheers Phillip -

    I think the gps system updates every second for its position and I presume the odometer does the same so any positioning errors get accumulated.

    I have the track log set to record every 50 metres so I suppose the accumulation of errors will be less.

    Now I'm beginning to understand

    Q

  4. #4
    Join Date
    May 2006
    Location
    Eastern Canada
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    Default

    I just turn the track log off and go with the trip calculator. It is always interesting to see your average and maximum speed too.

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