[OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

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planetshg
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[OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

Postby planetshg » Wed May 31, 2017 10:30 pm

Dear Harry,
fellow users,

I am kind of sorry to bother you with another thread like «halp! me OBD iz choppesy» - but maybe you're going to have the one, final idea.

In one line:
Choppy data from OBDLink MX BT AND WiFi with OP3 as soon as XGPS160 gets connected; default parameters and frequent recommendations to it have been tested.

En detail:
Until recently, I used a OnePlus 3 (Android 7.1.1 / OxygenOS 4.1.3) in conjunction with an OBDLink MX BT in a 2012 BMW M5. It worked flawlessly, apart from internal GPS being not so accurate (1 Hz). Even with default settings* it recorded smoothly and correctly.

Hungry for more GPS accuracy, I added a SkyPro XGPS160 to the mix, which connects via BT as well. OBD data became choppy instantly, showing as step-wise update with pauses inbetween where gauges aren't being updated. HLT reports system load being below 20%, often around 10%, when recording at 1080p using the phone's internal cam.

The phone is stock without root, no GPS helper app is installed, even OBDLink app is uninstalled. The only app capable of connecting to OBD and XGPS sensors is HLT GP 21.0.5. For testing purposes and to reduce any disturbances as far as possible, I even had Airplane Mode enabled, plus BT obviously. The M5's Bluetooth is disabled in Media and Telephone settings, all pairings with it were deleted (even those for phones absent completely).

So, I read a vast amount of threads in this forum Google found for obvious search terms and I tried these often-mentioned settings:
  • Exclude PIDs for MAP, MAF and Throttle: 010B01100111, even 09020160010B0105010601100111
  • Default Protocol: ISO 15765-4 CAN (11 bit ID, 500 kbps) that would get selected by OBDLink app as well
  • Adaptive Timing: Aggressive
  • Sequential Requests: Yes
  • CAN Multi Requests: 3 PID adaptive, 3 PID minimal, 2 PID minimal
  • OBD Extrapolation: Aggressive
Of course, I did not apply all of them at once but one-by-one, frequently falling back to default settings* and applying different sets of above parameters.

As all this did not solve the choppiness, I swapped the Bluetooth OBD sensor for a OBDLink MX WiFi, as I thought that the OP3's Bluetooth stack may be shi...overloaded. However, the problem still exists, regardless if using default settings* or some parameter combination like given above.

As soon as I disconnect the XGPS, the OBDLink MX BT will continue to work fine again.
Cannot say the same for the WiFi variant, because it's quite bitchy to get connected and wasn't so cooperative in the evening. Supposedly, it would be smooth then again, too.

Usually I consider myself a very tech-savvy person («Mr T is pretty handy with computers!»).
Next experiment will be done using a different phone (Nexus 4 Mini).

However I'd like to ask if you could spot any major mistake or path unexplored by me.
By any means, ask for details I may left out or logs I could provide.

Cheers from Wuppertal and thanks for reading,
Philipp

* Default Protocol: auto; Adaptive Timing: Optimized; Ignore NO DATA/NAK Replies: Yes, CAN Multi Requests: Off; Set UART Baud Rate: No; Exclude PIDs: empty; OBD Extrapolation: Adaptive


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Re: [OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

Postby Harry » Thu Jun 01, 2017 3:12 am

This is not about the GPS or the OBD input but rather an issue with a combination of GPS and OBD update rates not interpolated correctly by LapTimer. We had some threads on this too, but I'm using my smartphone right now and can't find it (so please search again). There is an OBD Extrapolation expert setting that influences this behavior. It is applied during recording and will not fix existing recordings.

It does not seem to help for all situations either. Instead a change in the interpolation approach would be required (major rework).

Harry


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Re: [OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

Postby planetshg » Thu Jun 01, 2017 11:25 am

From what I read on the forum, setting OBD Extrapolation to aggressive should be what's needed?
Unfortunately, that did not help so much in my case.
Got that old Nexus 4 settled with HLT meanwhile and will give it a try. Your reply took away some hope, however. ;-)


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Re: [OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

Postby planetshg » Thu Jun 01, 2017 8:33 pm

As you predicted, the other phone (Nexus 4 with Android 5.1.1) did not perform better.
It's a pity that this combination of top devices for Android does not work out well currently.

Can I help you in any way reworking the interpolation? ;-)


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Re: [OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

Postby Harry » Fri Jun 09, 2017 12:35 pm

planetshg wrote:As you predicted, the other phone (Nexus 4 with Android 5.1.1) did not perform better.
It's a pity that this combination of top devices for Android does not work out well currently.

Can I help you in any way reworking the interpolation? ;-)


Only be being patient until I find the time to revisit this area.

- Harry


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Re: [OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

Postby Sonertial » Sun Jun 11, 2017 11:50 am

I've been having this same issue, but with the Kiwi3.

I have found that I can fix the problem in my case, by lowering the Sensor delays.

Currently I have the following settings:
Sensor Delays
Dual XGPS: 0.3
Any OBD: 0
Internal Acceleration: 0.3
Overlay Syncronization
Video: 1

For me, this lines everything up and removes the choppiness. (I'd want to increase the accelerometer delay a bit more but it drops out if I set it higher than the GPS)


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Re: [OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

Postby gplracerx » Sun Jun 11, 2017 4:45 pm

There's another thread where it's also been pointed out that noise in the OBD wheel speed data is related to the OBD data not lining up with the GPS speed data. The sensor delays may need to be tweaked.


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Re: [OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

Postby habeb00 » Mon Jun 12, 2017 11:30 am

Sonertial, thank you for the delay information. I experienced the same choppiness in my last track outing and was using the XPS160, KIWI3 & GoPro Session. My RPM data was jumping all over the place.
Will have to run some test when the car is back online. Would be fantastic if this works, leaving my only concern with using the correct throttle PID for my vehicle.


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Re: [OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

Postby planetshg » Mon Jun 19, 2017 9:38 pm

Thank you so much, Sonertial - reducing the delays in this way is helping a lot!
It still is a mile away from the smoothness HLT got me used to - however, this way I can wait for Harry. ;-)

Which setting do you run for OBD Extrapolation?


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Re: [OP3+OBDLink MX+XGPS160] Choppy OBD data when XGPS160 in use

Postby Sonertial » Wed Jun 21, 2017 2:56 pm

planetshg wrote: ...

Which setting do you run for OBD Extrapolation?



Sorry for the delay in answering , good to hear the settings are helpful :)

I currently have it set to Aggressive. I've looked pretty closely at how the interpolation/extrapolation works, my opinion is that it is almost always better than taking the nearest measured value, hence Aggressive, which opens the interpolation/extrapolation window as wide as possible. The key is to set the delays so that the OBD replies are always within that window which is centred on the GPS fix time. (I think. Harry's probably laughing at me.)



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