Mychron5 GPS not accurate

Has anyone had this issue with their Mychron5? My laps are not plotting accurately so they don’t. line up for analysis.

I have the same issue when I try comparing it on different days. I am not sure what causes it, but my guess would be the position of the satellites on different days, and/or the number of satellites and strength of them on a particular day.

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Within RSA, check the values for GPS_Nsat (number of satellites) and GPS_PosAccracy. PosAccuracy should be around 0.6 and 0.7.

these runs were within an hour and a half but I will look at the GPS_Nsat and see what that says. Thank you for the reply!

Usually it’s caused by a lack of satellites in view.

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I am assuming this would also make lap times inaccurate? Is the Mychron 4 with beacon better for lap times and testing?

Interesting if the new S model, is better in that way

I haven’t noticed that it has any effect on lap times. I’ve looked at each versus the transponder timing, and they are all fairly close.

Ok good know, thanks

It’s all relative so the lap time shouldn’t be affected.

Gps is intentionally made a little inaccurate for national safety. It will change somewhat over the course of the day. Within a run, gps will be 100% accurate from one moment to the next. But when you overlay one run with another you’ll see they are different, it equally different over the entire lap. So use this as a tool to evaluate the shapes of your corners. Whether you late apex, diamond the corner or whatever.


Exactly this. I try to emphasize not to overlay the GPS traces to compared driving lines, but to look at the shapes of the lines to determine how two drivers are driving the corner differently.

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I haven’t tried this myself to fix this particular issue, but when runs don’t align in the measures graphs you can use the ‘lap insert’ function.

Gps lap insert is buried in the lap manager, tell it to align the run to a previous test - hopefully it aligns the GPS lines too.


The other thing I use it for is to see where my daughter uses the brakes and throttle in relation to a corner. I look to see if she’s trailing onto or off of the brakes and if she’s on the throttle later than she should. I rarely export it and overlay it on Google Maps, but keep it in Race Studio.

I had the same issue. If you look closely at your GPS plot in racestudio you will see your laps (yellow and green lines) overlap. This means you are essentially driving more than 100% of the track and therefore your laptimes will be slower than actual. In my case I also had laps that were incomplete (the GPS plot did not complete the loop) so laptimes were fastest than actual. Check all your data. I had this issue across around 30% of all laps regardless of track. I sent the mychron to aim for a GPS module replacement however this did not fix the problem. They have now replaced the whole unit so time will tell…