Smoothnes of OBD data

Discussion related to external OBD and other sensors
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PitrsRS
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Smoothnes of OBD data

Post by PitrsRS »

Hi,

what´s important for smoothnes of OBD data during overlay (except refresh rate)? I have OBDLink LX. I tried overlay yesterday and it´s really "shi*y".
I know sometimes I need to disconnect phone from BT of the car and keep only OBD and GPS to increase OBD speed rate. But this time it does not helped.

in expert settings I only changed Throttle position to D, everything else is in "standard" settings.

There may be a problem in OBD itself? It use to be OK some time ago, but then I had older FW in OBD adapter.
2016 SEAT Leon CUPRA 290 ST

HLT Grand Prix (Android) + OBDLink LX BT + XGPS160 + GoPro 7 Black
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Harry
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Re: Smoothnes of OBD data

Post by Harry »

There is a known problem in sensor fusion resulting in smooth, but stepped movements of OBD data. The problem occurs (at least) in situations with a high rate GPS and a lower rate OBD. E.g. 10 Hz GPS and 8 Hz OBD.

Furthermore, please check if you get consistent OBD readings. It is fine to have ups and downs in update rate by 1 or 2 Hz, but the rate should never drop to 0. The later means there is some problem in communication or connection.

- Harry
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Re: Smoothnes of OBD data

Post by PitrsRS »

Few years ago (approx 4), when I bought OBDLink I had refresh rate about 8Hz and faster, but in last 1-2 years I see rapid fall in refresh rate in HLT (I´m happy if I get over 6Hz). Maybe it depends on firmware on OBD? I can try some older firmwares. Or exclude all unnecessary PIDs?

On track, i had timer view, so I did not check rates on OBD :/ But yes, data are realy "stepped", you can see it in the picture (also on video it´s really annoying)
I tried DashWare and RaceRender and I saw RaceRender have a feature to artifically smooth data. Do you planning something similar in the app?
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2016 SEAT Leon CUPRA 290 ST

HLT Grand Prix (Android) + OBDLink LX BT + XGPS160 + GoPro 7 Black
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Re: Smoothnes of OBD data

Post by Harry »

Hello,

The rate variation is not a real problem as long as it doesn’t drop to zero - which signals a loss of communication. LapTimer applies a quite sophisticated approach to interpolate data correctly independent from varying rates. Or the other way around: rate variation is not the source of anything you will see in overlays. So I assume you run into the first problem I mentioned in my last answer. Do a short manual recording on your way to work using the internal GPS(!) and your LX. Data in gauges should be smooth.

On update rates: LapTimer utilized all known technics to raise OBD rates. You may need to adjust some OBD Tweaks to benefit from this. See the OBD / Engine document available on http://www.gps-laptimer.de/documentation Skipping PIDs is possible, but is not a big lever. There are better ones like parallel requests and ECU filtering.

Harry
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Re: Smoothnes of OBD data

Post by PitrsRS »

Hi Harry,

So I tried it only with internal GPS, and result is the same like before. You can see it in the picture. I checked expert settings. Before I had one custom PID defined (fuel), so I disabled it, without success. Also I make a short screen recording on engine page. Rate flows between 1 to 15Hz.
I double checked everything (I hope so). Also I tried several firmwares. I also disconnected smartwatch, so to the phone only OBD was connected via BT nothing else.

It´s possible there is a problem with data flow from the car?

and here is live video from app
[youtube]https://youtu.be/yUZEySMU1n8[/youtube]
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Re: Smoothnes of OBD data

Post by Harry »

Yes, this is too much... Please create a log as described in the Debugging OBD FAQ here in the forum.

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Re: Smoothnes of OBD data

Post by PitrsRS »

Ok, I will. Thanks Harry.
2016 SEAT Leon CUPRA 290 ST

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Re: Smoothnes of OBD data

Post by PitrsRS »

But. I tried OBDLink app, and I also noticed same problems there. If I look on revs and I try to slowly raise them, gauge is not smooth just like in HLT. So I think problem will be somewhere else :/ Unfortunately I don´t have access to any other car than VW brand (SEAT and Skoda) to try it on different car.
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Re: Smoothnes of OBD data

Post by Harry »

Do the log please, maybe we can see something we can work around.

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Re: Smoothnes of OBD data

Post by PitrsRS »

Hi Harry, I did a log, you should have it in your mail ;)
2016 SEAT Leon CUPRA 290 ST

HLT Grand Prix (Android) + OBDLink LX BT + XGPS160 + GoPro 7 Black
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