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MediaTek MTK GPS and "position pinning"

Posted by Ground Loop on September 26, 2010 at 11:36pm
I've been recording the NMEA output from a MediaTek MT3329 GPS with the DIYDrones firmware, and I noticed that it seems 'pinned' when in a stationary position.

Most GPS receivers wander around as the many small errors in GPS cause some natural drift in the position solution.  A few meters of constant wandering is expected.

The MTK has no wandering or drift at all.  Zero.  Not a single least-significant digit, over hours.

If I power it off and on, it will drift for a few moments before locking down.  The fixed position it choses can vary by 20m or more.

I believe this represents "position pinning", where the GPS has decided it is stationary, and retains the last coordinates, exactly, even when the position varies slightly.

Does anyone know for sure?  Is there a threshold at which it finally gives up and outputs a new position?

I'm not sure how this will impact position hold.  I'd rather it give unique solutions for each output, and let the Ardupilot do any smoothing or pinning.

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Tags: gps, mediatek, pinning, position
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Replies

  • Ground Loop October 19, 2010 at 7:08pm
    Never found out. BUT, it only seems to apply to NMEA. In binary mode, it doesn't appear pinned. Same for you?
  • Kevin Weekly October 19, 2010 at 6:07pm
    Did anyone find out what was happening here? I am getting the same issue where the gps position doesn't change even if we move the unit several tens of meters.

    Thanks!
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