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  • Hi Gordon,
    I've designed and programmed my personal GPS devices based on M8N and M9N.
    Data from a Ublox chip normally is very accurate, but I use the binary protocol and not NMEA.

    Attached are 2 files, 1 is data from the Bangle, the other is from my own logger at 5hz.
    I've highlighted the suspicious part in the Bangle screenshot.

    When I look at the track points

      <trkpt lat="52.477275" lon="5.065324">
      <trkpt lat="52.477113" lon="5.065425">

    There is 19m between them, 19m/s = 68,4km/h

    For my personal devices I use double for lat/lon data, it almost looks like the current grid is not dense enough.

    I used km/h NMEA data from the Ublox on another Bangle and it is spot on! (other wrist)
    So I really suspect the lat/lon data from the recorded file.

    The Ublox spec has 8 digits, the recorded file 6 (page 141)­221

    Could it be the difference between 32 and 64 bit?

    2 Attachments

    • Screenshot from 2021-06-23 20-10-02.png
    • Screenshot from 2021-06-23 20-04-17.png

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