RPM data is very "noisy"

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ckowalc
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RPM data is very "noisy"

Postby ckowalc » Fri May 22, 2015 4:10 am

I noticed the RPM data from my BT OBD reader is very noisy especially under wide open throttle. I used exponential smoothing in Excel to try to make the data look better but it seems like there may be a better way and maybe fix the issue at the source of the problem. I wonder if there would be a way to use the vehicle speed to prevent the spikes? Only issue I could see with this is when you clip the throttle on downshifting.

Here is a comparison video with top being smoothed and bottom being raw data (run through Dashware's filter I guess). Also just learned how to blur stuff so I was trying that out. :P



Also, on another note Dashware uses an throttle position scale of 0-100 and HLT uses 0-1 . I spent about a little while trying to figure out why the throttle data wasnt showing up. If anybody else has Dashware that is why, you need to adjust the throttle gauges to min:0 and max:1.


ckowalc
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Re: RPM data is very "noisy"

Postby ckowalc » Sat May 23, 2015 3:29 am

Here is a graph of the raw data (blue) vs. the smoothed data (red) from the same time range as the video posted above. Here it is clear what I mean by the noise in the data.

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Harry
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Re: RPM data is very "noisy"

Postby Harry » Sat May 23, 2015 6:11 am

I just searched the forum and found viewtopic.php?t=2237#p11630 Can you please check how OBD and GPS update rates relate for you configuration?

Harry


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ckowalc
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Re: RPM data is very "noisy"

Postby ckowalc » Tue Jul 14, 2015 8:05 pm

My latest recordings were 4.35 Hz for the GPS and 3.77 Hz for the RPM over a random 60 seconds.

I am using a Qstarz at 10 Hz but am having the issue in this thread: viewtopic.php?f=9&t=2062&p=15907#p15904


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Re: RPM data is very "noisy"

Postby ereynold60 » Tue Jul 21, 2015 8:41 pm

I can attest to the same behavior. Porsche Cayman S (981). I have Android GrandPrix edition, external GPS at 10Hz, and OBDlinkMX BT connected at 12-13Hz... I get noisy data under acceleration, and not only RPM, but also throttle position and wheel speed. I've yet to figure it out after fiddling with numerous settings for CAN Multi-requests, various PIDs, et.al.

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Harry
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Re: RPM data is very "noisy"

Postby Harry » Tue Jul 21, 2015 9:42 pm

Acceleration is measured using the built in accelerometer, not OBD. Acceleration is always a bit noisy and setting the level go smoothing is a difficult exercise. Smoothing to strong caps min and max values. Smoothing to a smaller extend leaves visible noise. Not a topic that is finally solved, but not related to the GPS/OBD discussion here.

For rpm and throttle, please test both with Multi CAN request and without. The later should remove the noise (the lower the OBD rate, the less noise).

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Re: RPM data is very "noisy"

Postby ereynold60 » Tue Jul 21, 2015 9:59 pm

Harry - I meant I get noisy OBD data (RPM, Throttle, Wheel Speed) when accelerating, as in going faster, full-throttle, increasing velocity... not acceleration, as in G-load.


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Re: RPM data is very "noisy"

Postby ereynold60 » Wed Aug 12, 2015 4:51 pm

With the results of some recent testing, v19.0.15 seems to be much smoother in RPM and Wheel Speed values from OBD... Harry - were there updates to this area?


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Re: RPM data is very "noisy"

Postby Harry » Wed Aug 12, 2015 8:59 pm

I do not think so... But a big piece of software like this often starts to do things one doesn't expect :-)


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OBD Data Jumpy in Overlay

Postby uncwes » Wed Sep 16, 2015 1:28 am

[Moved to original topic]

I'm having the same issue as was discussed in this topic: viewtopic.php?f=20&t=2997, but no solution was ever arrived at. The original author never replied that he got things working properly.

When I export data, or do an overlay, I'm getting crazy, jumpy fluctuations in the RPM, speed & throttle data.

I have a 2009 MX-5, OBDLink LX, and Qstarz 818XT GPS unit running on a Droid Turbo.

The Qstarz is the new addition. Things were fine when I used my phone's GPS for previous events but obviously was limited to 1HZ.

I've tried various settings for CAN to no avail. I'm thinking of sending in my log files but has anyone else had this problem and fixed it?

For the test I just did in my driveway, I'm seeing the crazy jumpy data but the debugging log is showing very consistent RPM updates of 10-20 ms.



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