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fenix 7X Pro SS, 20.16 and GPS

Sean C
2 months ago

Since upgrading to 20.16, GPS acquisition is taking longer on the hiking, walking, and running apps.  I'm set to sample GPS every second, and GPS is set to All+Multiband on each of those apps.

Before: GPS acquisition was instantaneous to a couple of seconds.

After: 5 to 10 seconds.

Also, I run and walk some well measured trails (used for 5k and 10k runs).  GPS distance seems to be consistently off by about 0.05 miles over a measured 1.6 mile loop.  (What has been measured independently and via GPS on older firmware as 1.6 miles is now measuring as 1.55 miles on 20.16).

Anyone else seeing this delay in acquisition time and shortening of GPS distance?

  • 0 2 months ago

    I have an opposite situation. It measures 5-10% more distance now. 

  • 0 2 months ago in reply to amarkov

    Yeah, I'm seeing a consistent 3-6% decrease in distance.  So looks like GPS is now having an average +/- 5% error rate compared to previous firmware.

  • +1 2 months ago

    The watch and Garmin Connect do not show the GPS distance. They use the combination of GPS and accelerometer data, and often the distance deviation is not caused by GPS, though rather by a wrong or lost calibration of the accelerometer-based estimation.

    To check whether the wrong distance it is really caused by GPS, open the activity in Garmin Connect Web and save it as Course (an option in the context menu when you click the cogwheel icon at the top right). The saved course then shows the true distance of the GPS track, without any influence of the accelerometer data.

  • 0 2 months ago in reply to trux

    Bingo!  At least for the distance shown on Garmin Connect Web and the watch.

    Do you have information on how to recalibrate the accelerometer?

    Also, this still leaves the greater GPS acquisition delay still unanswered.

  • 0 2 months ago in reply to trux

    How Do I Calibrate the Accelerometer on a Garmin Watch?

    support.garmin.com/.../

    Not possible to manually calibrate it.  My theory is the firmware upgrade reset the 'fine tuning' of the standard table provided.  Looks like it will just take some time to recalibrate to me.

    "Watches are pre-calibrated with a table of default values based on the averages of many runners and the calibration is refined every time the watch is used outdoors with GPS. In addition to the built in table, the watch will also adapt during its use to provide the best possible speed and distance when GPS is unavailable."

  • 0 2 months ago in reply to Sean C
    Sean C said:
    Do you have information on how to recalibrate the accelerometer?

    It should happen automatically, and improve as you do some outdoor runs under good GPS conditions. When it does not improve over the time, unfortunately the only way to reset the calibration is resetting the watch to factory defaults. Another option is using the HRM-Pro chest strap, which replaces the internal accelerometer of the watch. It is also much more accurate (moving on a simpler curve), and unlike the internal accelerometer, it offers the option to reset or pause the calibration.

    Sean C said:
    Also, this still leaves the greater GPS acquisition delay still unanswered.

    You may want to hard-reset the watch - sync, then press the Light button for some 30s till it completely shuts down (hold the button through the emergency alert, if it comes), wait little bit, and then restart. No worry, no data or settings will be lost with it. [more details]. Then delete the CPE file (ephemeris data) in the folder //GARMIN/RemoteSW/, and check for updates with Garmin Express.

  • 0 2 months ago in reply to trux

    Yes. There it shows a correct distance. But I want to have correct distance and pace during the workout, not after. 

  • 0 2 months ago in reply to trux

    That's interesting. I use indeed HRM Pro strap. Will try to recalibrate it. Thanks. 

  • 0 2 months ago in reply to amarkov

    agreed.  I wish there were a way to turn off the accelerometer adjusted data during a run/hiking/walking activity.  It's more important for me to know the actual distance during the GPS enabled activity.

  • 0 2 months ago in reply to Sean C

    I just checked and figured out that distance and pace setting for hrm pro was set to always. But I have not touched it so far. I set to indoor and will check.