Connection interruption every 30 seconds

  • We have several UAVs all operating with 1.8GHz Microhard modems and VOXL Flight for communication with the GCS (SkyNav or laptop).

    We've found the connection will drop for ~0.5-1 second every 30 seconds like clockwork when the problem begins, but when it starts and stops appears to be random (e.g. sometimes it happens immediately and other times can have a stable connection for >1hr without issue).

    Without touching the hardware (and testing in multiple locations to rule out an environmental problem), we've observed it starting on startup, after 6 minutes, 16 minutes, and 31 minutes of connection (to provide some examples). Then, every 30 seconds the connection will momentarily drop before fixing itself, with a visible interruption in UAV telemetry. Typically a reboot will not fix the issue.

    It only happens on a single UAV that we believe to be configured identically to others. We've also ruled out a temperature problem with the radio and every hardware factor we can think of.

    Our best idea is to re-flash the firmware as it appears to be a software bug, but wanted to check on the forums here in case anyone has run into a similar problem or has an idea for what it could be.


  • Dev Team

    @Ansel-Misfeldt Just so I fully understand the situation, you're only seeing this on one drone that has a VOXL Flight with a Microhard add-on board + modem installed?

    Could you try replacing the Microhard add-on board + modem with one from one of the drones that is working? If that works you could at least narrow it down to that specific board or modem.

  • @tom Yup, you're fully understanding the situation. Just the one drone is having this problem (with microhard modem+carrier board), all others seem perfectly normal.

    Tried replacing the modem + carrier board on the affected drone with a spare and it has the same behavior.

    Would the next step be to try re-installing VOXL Suite and redoing the microhard setup?

  • Dev Team

    @Ansel-Misfeldt Re-installing the newest System Image and VOXL Suite wouldn't hurt at all and should be very quick. I'm not convinced that it would solve the issue completely but it's something to try.

    From the information you've given me so far, the constant is the VOXL Flight and the rest of that drone's components (power module, wires, antennas?? etc.) so those are the things to check to make sure they're all good.

    Doing a re-flash is a good start as it will verify whether or not the software on on your VOXL Flight is good.

  • Dev Team

    @Ansel-Misfeldt Just so you know, this isn't an issue I've seen in the past so this failure mode is new to me.

  • @tom Thanks for your thoughts Tom, it was new to us as well! We seem to have managed to fix the problem but we're not entirely sure how / why. Our best guess is that was a software glitch with the Microhard radios themselves.

    I'm documenting what we found here in case anyone else runs into a similar issue in the future.

    We were able to eventually duplicate the same problem on another UAV that had previously been perfectly stable, thus eliminating the VOXL as a potential cause with two separate units showing the issue.

    We were testing a variety of settings today (e.g. channel, bandwidth, power of transmitter, which module is master vs slave) just to try and identify if anything made a difference. Eventually after re-setting the settings back to the microhard defaults (which we had done several times already), the problem mysteriously stopped. We've since kept a stable link open on two UAVs for the last ~6 hours without issue, so we suspect that there was some software issue that eventually cleared when we modified the settings. The last change we made was testing which module was master/slave, and after swapping them and then swapping them back the issue went away.

    Really puzzling issue, we're just glad it seems to be fixed. As I said, we suspect it was an issue with the radio and not with VOXL. Why it would be perfectly stable with one drone for hours and then have an issue with a different identical drone is beyond me.

    You guys do great work, keep it up!

  • Dev Team

    Thank you very much for the details. Sounds like a good tip for future is to just reset the default settings and start over.

  • @Chad-Sweet Yes, it usually is a good starting point. I do want to mention it took us 3 or 4 separate resets of all related radio settings before this particular glitch went away.

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