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Wrong lap times for Racepark Meppen

Posted: Sun Aug 23, 2020 7:55 am
by zekarus
We had yesterday some issues at Racepark Meppen. Pixel 3A and iPhone 11 both had to short rounds. It looks like the timer is stopping at a section on the other side of the finish line.

Image

Re: Wrong lap times for Racepark Meppen

Posted: Tue Aug 25, 2020 8:19 am
by Harry
Please export one lap this occurs for to both KML and HLPTRL and send it to harry@gps-laptimer.de. Add “Meppen issue” as a comment. Thanks.

- Harry

Re: Wrong lap times for Racepark Meppen

Posted: Tue Aug 25, 2020 9:37 pm
by zekarus
Looks like I have to wait for version 24 as I'm on Android 10.

Re: Wrong lap times for Racepark Meppen

Posted: Wed Aug 26, 2020 7:47 am
by Harry
zekarus wrote:
Tue Aug 25, 2020 9:37 pm
Looks like I have to wait for version 24 as I'm on Android 10.
Yes, or install the beta. It is pretty stable and will go to release soon.

- Harry

Re: Wrong lap times for Racepark Meppen

Posted: Wed Aug 26, 2020 8:29 pm
by Harry
Hello,

Here is the analysis of your data. The two pictures below show two of your laps which should actually be one. LapTimer detects start / finish after Turn 5. Explanation - see orange and red lines in picture #1: after passing turn 5, LapTimer received the driving direction (from GPS) shown in orange. Using a very big Wide detection corridor (red line), LapTimer considers this a situation s/f is passed and the lap is finished and the next one start.
1.jpg
1.jpg (396.58 KiB) Viewed 173 times
2.jpg
2.jpg (389.01 KiB) Viewed 173 times

It is pretty obvious, the corridor is far too big here. Measuring the distance from the map it is around 115 meters to the left and right. Assuming you use the default values, this 115 meters are a combination from the 80 meters Wide corridor plus GPS accuracy reported by the GPS at this time (I assume around 35 meters).

So while I do not see there is a general problem with the track set, we have two problems summing up: accuracy in that corner is comparably bad. This repeats for other laps. This is usually because of driving direction and the way your car's body shields this day's satellites. So we get 35 meters corridor width added where we have something like ten usually. Furthermore the track is a small one and the default wide corridor is probably too big here.

To work around the next time, please reduce the Wide corridor width to something like 50 meters.

You can join your fragments too. Select the first segment lap from Lap List, follow Fixes / Positions, and select the join icon in the bottom.

- Harry