GPS/Accelerometer out of sync with OBD II data?

EatMeerkats · Post by **EatMeerkats** » Sat Jul 25, 2015 4:00 pm

Hi Harry,

Thanks for the great product! I recently got an OBDLink MX Bluetooth for use with HLT, and I tried it for the first time at an autocross recently. I'm using an external GoPro for video, and I've done my best to manually sync the data up with the video in DashWare, but the accelerometer readings still seem a little out of sync. I am using the default sensor delays in HLT.

The resulting video is here. Is this a case of not syncing the data with the video correctly, or a case where the OBD II data is not in sync with the phone's internal sensors? Any help would be greatly appreciated... thanks in advance!

Post by **Harry** » Sat Jul 25, 2015 4:55 pm

Thanks!

No band width currently, I can't watch the video right now. But if acceleration and OBD is out of sync, you need to adjust one of the delays for the next run.

- Harry

Post by **Harry** » Sat Jul 25, 2015 4:57 pm

I meant one of the OBD / accelerometer delays. Adjusting video sync alone will not help here...

ereynold60 · Post by **ereynold60** » Tue Aug 11, 2015 10:10 pm

For my setup (LG G3 Android, OBDLinkMX BT and Dual XGPS160A)... I found that I needed to adjust the "OBD delay" value in the expert settings. This value has a default of 1 second, and I found I needed to set it at 1.8 seconds to be in sync with GPS. My OBD data was coming in too early related to both video and GPS.

How to do this?

I exported a lap in CSV file, open in Excel and plot GPS and OBD Wheel Speed columns... then use a formula like VLOOKUP the create an "adjusted OBD speed" value in a separate column... and fiddle with a pseudo-delay until they match: Here is a 'formula' for adding 0.7 second delay:

=VLOOKUP((E10-0.7),E$2:Z$1516,22)

This looks for an entry that is 0.7 seconds later and uses that OBD value...

So, Excel never makes sense unless you are the one doing it... but the idea is to try and find the difference in GPS and OBD speeds and using that to adjust your OBD delay value.

After I did this, made some test runs and did some fine tweaking... and now have GPS and OBD sync'd.

I still need to adjust video delay from default of 1.0 down to 0.6 ... this I set by listening to audio for a gear shift and having it match OBD RPM.

EatMeerkats · Post by **EatMeerkats** » Tue Aug 11, 2015 10:37 pm

Thanks, ereynold60! I still need to buy an external GPS receiver (because using my phone results in only 1 Hz data collection), but I should be ordering one today/tomorrow and will give that a try this weekend.