Not recording all laps?

mjkuhno · Post by **mjkuhno** » Mon Mar 31, 2014 2:54 pm

Hi Harry and Laptimer community,

This is my first season using Laptimer and while I'm thrilled with it I seem to be having an issue where not all laps are being recorded.

I ran this past weekend on the motorcycle at VIR North and each session was 15 minutes (they were running 4 groups) though the timing of Laptimer seemed to only capture 8-10 minutes (4-5 laps; it was raining). I have the whole video portion, but at some point the telemetry just stops. Actually, in reviewing one video it picked up the corners again but the position on track, speed etc. wasn't there.

Is this a problem in Laptimer (upgraded to the latest version of GP this past Friday) or could it be something due to the rain?? Incidentally, I was using the internal iPhone GPS/accelerometer. I tried to update my Dual 150 unit last week to the compatible firmware and something went wrong...had to send it back to Dual

for some TLC.

I'm heading back to VIR North on April 7th and would really like to get this sorted before then - so any help would be appreciated.

BTW - also not ruling out user error; actually might be the primary cause since this is the first time I'm really using it (except for trial use in the 'neighborhood track' - ha!)

Thx
- Mike

bulls23 · Post by **bulls23** » Mon Mar 31, 2014 3:09 pm

mjkuhno wrote:Hi Harry and Laptimer community,

This is my first season using Laptimer and while I'm thrilled with it I seem to be having an issue where not all laps are being recorded.

I ran this past weekend on the motorcycle at VIR North and each session was 15 minutes (they were running 4 groups) though the timing of Laptimer seemed to only capture 8-10 minutes (4-5 laps; it was raining). I have the whole video portion, but at some point the telemetry just stops. Actually, in reviewing one video it picked up the corners again but the position on track, speed etc. wasn't there.

Is this a problem in Laptimer (upgraded to the latest version of GP this past Friday) or could it be something due to the rain?? Incidentally, I was using the internal iPhone GPS/accelerometer. I tried to update my Dual 150 unit last week to the compatible firmware and something went wrong...had to send it back to Dual for some TLC.

I'm heading back to VIR North on April 7th and would really like to get this sorted before then - so any help would be appreciated.

BTW - also not ruling out user error; actually might be the primary cause since this is the first time I'm really using it (except for trial use in the 'neighborhood track' - ha!)

Thx
- Mike

I think it comes down to bad reception. If for example you had it on your handlebar the reception is isn't that great because of you leaning over it. I think most bikers use an external GPS in addition, mounted on the back of the bike. And of course rain doesn't help, GPS doesn't like water (and also does not work under water

) so like I said, must have been bad reception and you should be fine using the Dual receiver.

mjkuhno · Post by **mjkuhno** » Mon Mar 31, 2014 3:15 pm

bulls23 wrote: I think it comes down to bad reception. If for example you had it on your handlebar the reception is isn't that great because of you leaning over it. I think most bikers use an external GPS in addition, mounted on the back of the bike. And of course rain doesn't help, GPS doesn't like water (and also does not work under water ) so like I said, must have been bad reception and you should be fine using the Dual receiver.

Thanks for the reply, I appreciate it. I was thinking the rain might contribute, but to be clear, the phone is mounted in an Optrix case on the tail of the bike which puts it in the clear.

It was raining pretty damn bad though so perhaps all of the rain in the atmosphere was contributing; but routing to the track with my iPhone and Google maps during driving rain (in the car, not on the track bike) wasn't an issue, so

bulls23 · Post by **bulls23** » Mon Mar 31, 2014 3:19 pm

Maybe I should clarify too:
Those are my experiences in heavy rain. If you google for GPS and rain the answer usually is it should not affect GPS reception...but your problems still sound like bad reception to me.

Post by **Harry** » Mon Mar 31, 2014 3:20 pm

The requirements for routing are a lot lower than that to derive exact lap times. Routers can use additional data like known streets etc. to compensate missing reception. Maybe you want to export one session and send it to me for analysis. Please select a lap from an incomplete session, select "Session" as scope, and .hlptrl as the format for export. Send that file to Harry@gps-laptimer.de

- Harry

P.S. Rain is definitively an issue when it comes to GPS accuracy.

mjkuhno · Post by **mjkuhno** » Mon Mar 31, 2014 3:47 pm

Hi Harry - thanks for the quick reply. I just sent the session to you for review. Hopefully it was just rain and it'll work better for dry days/sessions.

Btw - I know this was slow; first day of the season with rain...yech!

Post by **Harry** » Mon Mar 31, 2014 4:33 pm

Thanks for sending your data. I believe it is about GPS accuracy.

Looking into the overall accuracy, you can see quite some areas of low accuracy:

: iOS Simulator Screen shot 31.03.2014 17.18.23.png (45.7 KiB) Viewed 3681 times

Having a deeper look into the situation on the start / finish line, it becomes obvious that besides accuracy (which is typically added to the detection corridor to work around issues like this), the positions recorded show either a drift in GPS, or a line driven on the left of the track when starting and on the right of the track when finishing. Although any of this items should typically be handled well, the combination from rain, accuracy, drift, and line has probably been too much for the missing laps.

: iOS Simulator Screen shot 31.03.2014 17.24.17.png (51.61 KiB) Viewed 3681 times

Hope that helps,

Harry

mjkuhno · Post by **mjkuhno** » Mon Mar 31, 2014 7:30 pm

Hmmm - they recently repaved VIR. I wonder if the original points were taken on one side of the near side of the track, by the kink, and I was out further to come back across the kink?

Would there be any benefit to recalculating the lap(s) and setting the accuracy to wide?

Post by **Harry** » Mon Mar 31, 2014 7:51 pm

For triggers with direction, the detection corridor is always wide. The setting applies to triggers without driving direction only. Looking into the current map view, the trigger position looks fine. But please check yourself, I have never been to VIR

: iOS Simulator Screen shot 31.03.2014 20.37.16.png (353.05 KiB) Viewed 3674 times

- Harry

mjkuhno · Post by **mjkuhno** » Mon Mar 31, 2014 8:24 pm

Yes, that's right - that's VIR.

Ok - ill chalk it up to another learning experience for the weekend just like first time in driving rain with rain tires (and even some sleet!) and check it out again when I'm back there April 7th.

Thanks much Harry - the app is great!

Not recording all laps?

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