10Hz GPS but lines not smooth

edited April 19 in RaceChrono for iOS
I'm facing a bit of an issue with GPS accuracy. I have the Garmin GLO 2 but the satellite count varies significantly and it doesn't seem to deliver (or RC isn't showing) 10Hz worth of data given the lines in the RC track position analyzer. In the image below I've plotted # satellite count over the track and you can see the position is frequently inaccurate and not sampled frequently enough to create a smooth line.

https://ibb.co/nrcYdkr

Is there a setting in RC that will smoothen out the track position lines?

Would it help if I use multiple GPS devices together? Can RC interpolate within the two devices and pick the most sensible GPS location data points to show a smooth line?

Comments

  • aolaol
    edited April 18
    @M3_Dude Which phone, and which RC version are you using?

    The Garmin GLO should give you 3-4 updates per second on iOS (not 10 Hz even if they advertise so!), so I suspect you're suffering from some kind of problem in the Bluetooth connection. That looks like a lot less than one update per second.

    It could be a problem with the GPS signal too, if your Garmin GLO was not in the optimal spot. The satellite count goes often to 5-6 on your screenshot, which could indicate a low signal. You should be seeing ~10 satellites always.

    RaceChrono supports only one GPS, and mixing and matching the data doesn't work that well, as the both GPS would be fixed to different set of satellites.
  • I'm on RC 7.5.2 using a Samsung Galaxy S20 5G.

    I'll reposition the GPS for the next track day in 6 weeks.

    Did you notice significantly smoother lines when you tested the 25Hz Racebox Mini vs a "10Hz" GPS?

  • aolaol
    edited April 19
    OK, I was confused as this was posted to the iOS category. So never mind my previous comment about iOS.

    Garmin GLO should be 7-8 Hz on Android.

    If the GPS was not in the optimal spot, I would move it first.

    Note that there is a problem on Samsung phones that have Android 12. The Bluetooth stack has a bug that causes bad update rate on Garmin GLO and Dual XGPS. The RaceChrono v7.5.2 already has a workaround to this, so I wonder if it's working or not ... Worked on my phones at least when last tested it, but I'll re-test.

    RaceBox Mini is much better, but Garmin GLO should be much much better than your screenshot. Basically its crap data, and certainly problem with either GPS signal or Bluetooth.
  • Ok. I won't wait till the next track day then. I'll change the position and drive on a multi-lane highway and see if it does better.

    Is there a special setting I need to select to enable the GLO workaround in RC?

  • aolaol
    edited April 19
    The setting can be found at RaceChrono > Settings > Expert settings > Bluetooth update rate workaround. But it should be applied automatically on Samsungs. I guess it's work testing it as "On" as well as "Automatic".
  • aolaol
    edited April 19
    @M3_Dude can you do RaceChrono > About > Dump (the button on the top toolbar)? It will let me know your RaceChrono configuration in detail.
  • Just FYI, usually I put the GPS on the dash in my car and it works ok; but the other day I rode as a passenger with someone else, and held the same GPS in my hand. It was only a bit lower than I usually mount it, but the data received was way worse.
  • Dump sent. That was so easy!

    After sending the dump, I changed the Bluetooth workaround from automatic to enabled.

    I'll mount the GPS to the sunroof glass and test next.

  • Repositioning worked. High satellite counts and could track me changing lanes on the highway.

    How much better is the race box mini?

  • I have a Garmin GLO2 and a RaceBox Mini, both are good, but the Mini is incredible, also the RaceBox app is good for car performance benchmarking.

    Racebox Mini Pro's

    Extremely precise and smooth(25hz)

    Good native app

    Easy, almost auto connection, no power on button

    Larger battery

    Usb C port, you dont need to go with your prehistoric mini usb everywhere xD

  • Awesome. Will get mine in a few weeks.

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