Harry's GPS Suite Forum

So Ive exported the files from Harrys to csv etc and got them on my PC alongside GoPro videos triggered seperatly.

Im trying to overlay them both within RaceRender. The laps were 6-8 per session. I can sync 2-3 then it goes out by 5 plus seconds at some point and gradually looses all sync.

Ive got 5-6 seasions each with multiple laps. I have out laps, sync up on start line.

The data does have some bugs as it misses the start/finish line reset every 4/5 laps but doesnt bother me too michz guessing I can probably adjust and fix the raw data if I wanted to.


Additional 'odd' point is previously in Adobe Ive sliced each lap and then taken that video length as the lap time (50 fps) and broadly this equates to what Harrys has captured. Most are 1:35s and consistant. But on the video slices Ive got some 1.29 and 1.31 which Harrys doesnt. Im guessingg Harrys with only 1Hz on an iPhone is 'at fault' with inaccuracies and the video is correct?



I will ise Harrys to trigger GoPro next time but I was having issues of the GoPro WiFi link 'terminating' after being idle for a few minutes without car movement. Is this normal? Think I can do some advanced settings and give Harrys the GoPro Wifi password within the app. Still experimenting but have to wait between track days to test anything so its a drawn out process.

Thansk for any/all help in advance.

I can't comment in RaceRender and don't know how it handles the timing information used by LapTimer. You can assume the timestamps included in the CSV files are precise and sound as long as you had no GPS drop outs. Timestamps are from GPS and will not run too fast or slow ever. Video frame timing is a lot more complicated.

- Harry

Its a CSV file and as you said, has GPS timestamps (in GMT I might add - not the local time but adjusted for that to match up to the videos). Signal was 3-4 on GPS. I guess the 1Hz may limit accurate lap times as it must make assumptions in between the two readings to estimate at X time the Start/Finish was crossed. Hence if I am right between T1 and T2, hence cross the start/finish at T1.5 ish that maybe why it misses the start finish and my laptime isn't recorded and effectively doubled.

Thanks

GPS timestamps in CSV are UTC time. A 1 Hz rate is no problem at all as long as the software is able to do proper interpolation. Taking speed development into account, the time a trigger has been passed can be calculated to 0.02s or better accuracy. Not sure however, if RR requires an export already interpolated. LapTimer exports raw data measured and applies its interpolation within the app only (e.g. during overlays or when detecting triggers).

- Harry