Lap Time Accuracy

[PS14]

I have a 8 lap heat race that I logged, and i'd like to know why the GPS generated lap times seem so generic compared to the lap times recorded by Race-Monitor (uses a transponder). I turned Auto Race Track detection OFF and entered my Start/Finish coordinates. I also have a sector0 coordinate as well.

RCP TRANSPONDER
LAP1 19.00 18.840
LAP2 18.40 18.523
LAP3 18.60 18.546
LAP4 18.40 18.424
LAP5 18.60 18.535
LAP6 18.60 18.733
LAP7 18.60 18.594
LAP8 18.60 18.629

[stieg]

Hey PS14,

What version of the firmware are you running and what type of RCP are you using? Cheers?

[rdoherty]

Hi PS14, can you upload your log file somewhere for us to take a look at? Thanks!

[toga94m]

I have a 8 lap heat race that I logged, and i'd like to know why the GPS generated lap times seem so generic compared to the lap times recorded by Race-Monitor (uses a transponder). I turned Auto Race Track detection OFF and entered my Start/Finish coordinates. I also have a sector0 coordinate as well.

RCP TRANSPONDER
LAP1 19.00 18.840
LAP2 18.40 18.523
LAP3 18.60 18.546
LAP4 18.40 18.424
LAP5 18.60 18.535
LAP6 18.60 18.733
LAP7 18.60 18.594
LAP8 18.60 18.629

Your RCP lap times are all multiples of 0.2 seconds, which is a 5Hz rate. What's your logging rate? In theory the GPS on a newer unit can log at 50Hz (0.02 seconds per update) but I don't know how accurate position updates are at that speed. GPS position accuracy is maybe +/-20 feet, which is a large percentage of the distance of a lap that only takes 19 seconds.

I ran 6 passes of an autocross this weekend, with GPS start/finish set manually at the start & finish timing lights, and my RCP MK1 laptime wasn't very close to the optical timer, even on a 40-second run. It was detecting start & finish though.

[PS14]

Ryan/Stieg Sorry, i should have included that. I have the MK2 running V2.9.0. you got a spot I can upload to, the files to large for here?

toga94, do you use the AEM Data?

[PS14]

I uploaded it to dropcanvas. heres the link: http://dropcanvas.com/9swus

[rdoherty]

Are you viewing these lap times in the RaceCapture app or somewhere else? In the log the times have enough decimal places to give 3 significant digits. I'm thinking this is just a display bug and not logging.

For example I see a laptime of 0.3083 minutes. Which is 18.498s. But if the app is rounding or trimming, this may cause it to show up as 18.50s or 18.40s.

[PS14]

those came from AEM Data, but I see similar results in podium. so all time is recorded in ms? now the sector times make a little more sense.

[rdoherty]

Got a link to your data in Podium? I will take a look.

[PS14]

https://podium.live/events/a-s-5-20-2016-kd14

[rdoherty]

Thanks! Yeah it's a display bug, your laptimes are recorded with much more precision. I'll fix it today.

[PS14]

Thanks, looking at the log and knowing its in ms the data makes more sense. now I just gotta figure out how to get Laptime/Sector#/Sector time to display in AEM.

I understand the transponder and GPS times wont ever match. is there an impact to the time GPS times since its got a 5-8 feet fudge factor?

so much data, so many questions. Thanks for the quick responses.

[PS14]

I pulled this data out of the log. if I compare the laptime to the transponder time, theres major variances (+/-). with the sector times, theres some issue (drivers not that consistant)

LAP LAPTIME S0TIME S1TIME
1 41.7 16.302 9.702
2 18.798 9.102 9.498
3 18.6 9.102 9.498
4 18.498 9 9.498
5 18.402 8.898 9.6
6 18.498 8.898 9.6
7 18.702 9.102 9.6
8 18.702 9.102 9.498
9 18.6 9.102 11.4
10 27.402 16.002 0

[rdoherty]

RCP doesn't fully support sector times, so you can ignore those for now.

[rdoherty]

I dug into this more, I don't think this is a display issue, the values actually do end up as numbers ending in 0. This is probably due to 10HZ GPS.

Can you upload your configuration? Podium is recording that your sample rates are all 0, which is impossible. Thanks!