Harry's GPS Suite Forum

I'm more confused after reading threads on here so I'm creating one for my problem. I'm using Galaxy s3 running android 4.3. I'm using Qstarz 818xt external Bluetooth at 10hz and for ODB I'm using an odblink mx that HLT reports running about 10hz.

this is a short video of where I stand now in my configuration:
ODB 1.5s
GPS 1.5s
Accelerometer 1.5s
https://www.youtube.com/watch?v=J9F4s8TVG10

using the default sensor delays of 1.5 for gps and 1.0 for ODB and .5 for accelerometer my data cannot be synced properly to dashmaster at all. The RPM shift points are about a half second off. I'm gotten the shift matching the sound on my recordings for the shift to what looks almost correct using 1.5s for ODB sensor delay but my real confusion lies in that my ODB is 10hz, shouldn't I be decreasing the value but decreasing the value puts it out of synch even worse so with it now at 1.5s for ODB it's at least pretty damn close but its confusing, If I move it down to .5 the difference between the sound of my car shifting and the rpm guage showing the shift is like 2 seconds. doesn't make sense to me. Should be adjust this value up or down to further refine the ODB?

Secondly, the accelerometer I set to match the other two, I notice when braking almost stopped the lineal decal is still relatively high even though stopped so I need to drop this down to the default of .5, I think that was the default for the accelerometer and while on that topic does HTL use the ACCELEROMETER from the phone or from the GPS position and calculate the value?

Lastly the GPS sensor delay? The Gforces for Lineal and lateral are coming from the accelerometer I presume so I presume I should probably just leave this at the default of 1.5.

I can live with other pieces not being perfect at this point but this really frustrates me. The same behavior is exhibited in dashware as well as racerender.

if anyone can suggest what to change and whether increase or decreasing a value based on the video linked in this message you have my gratitude. Thanks
BoomSpoon

This *is* a complex topic and I regularly find myself mixing up negative and positive changes As you seem to be pretty advanced in dealing with this topic I just want to add some hints here:

• Higher than usual update rates (standard assumption is 1 Hz GPS, 3 Hz OBD, 30 Hz acceleration) will allow reduced delays. So for a 10 Hz OBD stream, it seems to be logic you reduce that delay. As all the values are relative to each other, there should be no reason to change GPS and acceleration at the same time.
• Delays are applied during recording (the time LapTimer merges all the streams). So in case you expect a change in results, you need to record something new.
• While it is a good idea to find the sync point using audio and rpm, do not use the gear display to synchronize. Gear is not delivered by OBD but is calculated from rpm, tires, speed, ratios. So gear will always be behind until the clutch is fully engaged again - often a second after the gear has actually been changed.
• When using acceleration to sync, first make sure it is valid at all. LapTimer's calibration works on tracks only, forces on public streets are usually too low to finish the last calibration step. LapTimer uses measured acceleration, but you may override it by a GPS based recalculation (in Lap Details / Recalculate).

In terms of perception when watching the result, the most important sync is between audio and rpm (if available) - and this is what you need to adjust in the over layers.

- Harry

Harry wrote:This *is* a complex topic and I regularly find myself mixing up negative and positive changes As you seem to be pretty advanced in dealing with this topic I just want to add some hints here:

• Higher than usual update rates (standard assumption is 1 Hz GPS, 3 Hz OBD, 30 Hz acceleration) will allow reduced delays. So for a 10 Hz OBD stream, it seems to be logic you reduce that delay. As all the values are relative to each other, there should be no reason to change GPS and acceleration at the same time.
• Delays are applied during recording (the time LapTimer merges all the streams). So in case you expect a change in results, you need to record something new.
• While it is a good idea to find the sync point using audio and rpm, do not use the gear display to synchronize. Gear is not delivered by OBD but is calculated from rpm, tires, speed, ratios. So gear will always be behind until the clutch is fully engaged again - often a second after the gear has actually been changed.
• When using acceleration to sync, first make sure it is valid at all. LapTimer's calibration works on tracks only, forces on public streets are usually too low to finish the last calibration step. LapTimer uses measured acceleration, but you may override it by a GPS based recalculation (in Lap Details / Recalculate).

In terms of perception when watching the result, the most important sync is between audio and rpm (if available) - and this is what you need to adjust in the over layers.

- Harry

Ok, I think I follow you. So with the sensor delays being relative I think I understand it makes sense to change only one of the values. The accelerometer from my S3 seems to be at 25hz so I'll make that tweak to update rate and set the Sensor delay back to the default of .5 for the accelerometer. What you said about the track makes sense as during testing I forget this step is taken care of during the first hard braking action so I think for my street testing I understand the "recalculate is definitely the better option.".

so, I'll keep messing around but I'm gonna reset the sesor delays back to default and reduce the ODB sensor delay from 1.0 (default) to 0.4 and since that's relative see what I get.

my ultimate "GOAL" is to be able to import the video and .CSV file into Dashware or RaceRender and not have to adjust the synchronization at all. That's the lovely little "fantasy island" I'm living on

Thanks for the tips, If I find a super awesome config for my setup I'll attach my final resolution.

Later.

The bad thing is there is no "correct" configuration. It depends so much on individual sensors, connection types, smartphone that a super precise setting requires individual calibration. The good thing is you will not need to adjust it all the time. Once it is done and you keep your configuration, you don't need to readjust it. Finally, for most users the standard settings is fine. The better solution planed for some time already is an auto calibration on channel basis (i.e. not event sensor). There are relations between noise and rpm, between GPS and OBD speed, between speed increase and longitudinal acceleration and so on. One day, LapTimer will do all of that for you

- Harry

Thanks but this is just pointless on a Galaxy S3 and android 4.3. I'm sick of it now, until Kit Kat comes out for the S3 or I get another phone like an S4 or S5 which I can't upgrade until September but I'm done. No matter what I try this just will never work properly with the S3 (at least my model) and android 4.3 and I can't mount my tablet (it's too damn big) but since it runs android 4.1.2 harrys seems to work just fine with it, can encode videos, can record using my 818xt and ODBlink MX without any stupid synchronization issues using the default values but not my S3 running android 4.3, everything is just a problem.

I quit.