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Instinct UltraTrac use cases and distance issue + firmware question

kidney_thief
over 5 years ago

Hi,

I've read multiple threads (one including instinct here) about UltraTrac. I use Ultratrac for walks during recovery/injury and discovered that distance is off by 50% in comparison to GPS both in Instinct and my wife's Vivoactive 4s. Does the error get smaller with greater distances? How come the error is so big if the GPS path is almost the same (just hoping maybe some dev will break the NDA Laughing)?

Question about firmware - does automatic firmware update include GPS firmware or do I have to update this seperately? I'm using 6.60 for Garmin and 2.60 for GPS. Is this the latest GPS fw (I know 7 is in beta or staged rollout for watch)?

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  • 0 over 5 years ago

    Yes, Garmin uses a clearly wrong implementation of the distance calclulating algorithm - whenever the watch loses the GPS signal (and it does not matter whether it is on purpose like in the UltraTrac mode, or due to a limited GPS signal near obstacles, in the standard GPS mode), it considers you did not move at all between the two known key points. So, instead of interpolating and adding the distance of the two known key points, it excludes the section without GPS signal from the distance calculation entirely (as if you moved from the last point to the new one by teleportation).

    Unfortunately I am not quite sure Garmin is willing to do anything about it - the problem is well known since years, and the algorithm was not modified anyway.

  • 0 over 5 years ago in reply to trux

    Thanks for in-depth explanation Slight smile I guess I'll default to GPS then, since I rarely do activities longer than 5 hours. UltraTrac seems a fine solution to graph multi-day hikes though. I guess I'll take a look if it's possible to correct this by calculating the distance from GPS file and reuploading activity. Should be fairly easy to code Slight smile

    BTW. I'm in middle Europe - any benefits from using GPS+Glonass?

  • 0 over 5 years ago in reply to kidney_thief
    kidney_thief said:
    I guess I'll take a look if it's possible to correct this by calculating the distance from GPS file and reuploading activity.

    You can do it even simpler - just export the activity as a GPX file, and import it back either as a new activity (you may need to change the date), or as a course - it will then show the correct distance. Alternatively, just drop the GPX file into Google Earth, or read it with one of the countless GPX tools available both as apps or as online tools.

  • 0 over 5 years ago in reply to trux

    Excellent! This way I can regain distance info for multi day hikes. Thanks Slight smile