Locator Tracks Reset

tcm5210's Avatar


21 Jul, 2020 05:55 PM

We use locators to track field members using InReach devices and helicopters participating in search and rescue operations. Sometimes, a locator track will disappear and start over. I believe this happens when a locator goes silent for a while, then comes back online. SARTopo seems to recognize that the gap between points is too large to reasonably continue the track. Rather than starting a new track, it deletes the old one and starts over.

Can anyone confirm whether this theory of the behavior is correct?

If this is, indeed, what is happening, then the behavior is not ideal. We would prefer to retain a record of the entire track, regardless of gaps. We have a workaround planned, but we would like to consult with the SARTopo team before we put any work into it.


  1. Support Staff 1 Posted by Julie on 21 Jul, 2020 09:06 PM

    Julie's Avatar

    Hi TC,

    The locators feature was originally designed to just give a recent history of locations and not be a full track feature. The function was meant for providing situational awareness of where teams are at in the field, but not to be a proper track.

    We have a new "location sharing" layer that we are in the process of developing currently. In the meantime, I suggest proceeding with your work-around if you wish to preserve the locations sent from the InReach.


  2. Julie closed this discussion on 21 Jul, 2020 09:06 PM.

  3. tcm5210 re-opened this discussion on 21 Jul, 2020 09:51 PM

  4. 2 Posted by tcm5210 on 21 Jul, 2020 09:51 PM

    tcm5210's Avatar


    Thank you for the quick answer. We look forward to the new "location sharing" layer and will gladly volunteer to beta test when it reaches that stage of development.

    Can you provide specs for how the locators feature works now? Is there a limit to the number of points in a track? And does the track reset when a point is received after an interval of no activity, as I speculated? If so, what is that interval?

    Our workaround is to route the tracking records through a program that will monitor the activity and anticipate a track reset. Rather than allowing a reset, our program will spoof a different ID for the locator, thus prompting SARTopo to start a new track for what it thinks is a new locator. We can tinker with this until we get it working, but it would help for us to know the exact conditions under which SARTopo will reset a locator track.


  5. 3 Posted by Stephen Dougher... on 23 Jul, 2020 04:55 PM

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    How are you tracking the helicopters?


  6. Support Staff 4 Posted by Ben Lantow on 24 Jul, 2020 12:08 AM

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    Locators are integrated into SARTopo to provide live satellite tracking. The design is intended to provide location tracking. If you wanted to archive tracks for future specifically from inreach devices you would need to export from Garmin and import them as tracks. However our application allows for recording tracks on a search and as soon as they return to cell service area the track will automatically sync back to the search map. Using the combination of live viewing and recording tracks on the phone app may provide a better experience. The "workaround" you list above is going to be tricky and may cause issues. Currently the logic for locators has the track reset if any of the following conditions are met:
    - the position report is more than a day after the last one - the position report is more than 20km from the last one - position report N is more than 5km from N-1 and N-1 is less than .5km from N-2 The total length of the track is limited to 500 points


  7. Ben Lantow closed this discussion on 24 Jul, 2020 12:08 AM.

  8. tcm5210 re-opened this discussion on 24 Jul, 2020 12:11 AM

  9. 5 Posted by tcm5210 on 24 Jul, 2020 12:11 AM

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    Those details are very helpful. Thank you!


  10. Support Staff 6 Posted by Ben Lantow on 24 Jul, 2020 12:31 AM

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    We think most likely you're running into either 500 points or N/N-1/N-2 rules. Nowhere in the near future are we going to change this logic, but at some time in the distant future we may do something different. Really we added trackers to show live locations more than to record tracks. You'll see the new locations layer here soon and it's a little bit different.


  11. Ben Lantow closed this discussion on 24 Jul, 2020 12:31 AM.

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