When is the best time to use filtering with my Pico?  I was watching an alternator ripple with a bunch of noise, would you use it then?  I was watching 2 TPS signals on a GM TAC with a bunch of noise especially when running, would you use it then?  Would filtering on a Pico keep you from seeing a drop out?

Thanks for any input from a novice user.

Sveddy,

Heavy handed use of filtering can certainly obscure important information.  It is not advisable to use it on high frequency stuff like secondary or primary ignition.

I recall a post on another forum where everyone was baffled by a Pico capture of an EDIS CKP that would reduce amplitude as RPM increased.  The problem was user error.  A 1kHz filter was deployed which filtered out the CKP when its frequency approached that threshold.  See images.

If you are using a 4000 series scope, you have a LOT of power there.  Oversampling can detect and display a lot more noise.  Dialing down the sampling when it is not necessary will reduce the noise as well.

Filter is best used on slower signals that you want to shave the hair off of.  You can also make your capture with or without filter and then apply or remove filter from the capture later to get the desired effects.

We will actually be discussing these techniques in our Group Therapy session this Thursday and it is also the subject of our next tutorial movie update.

Feel free to save out a screen of your capture and post the data file here.  You can't really show a PicoScope capture with just an image.   ;)

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Here is the complete file.

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Sveddy,

Thanks for sharing that.

I think the activity in your ripple is the 400Hz field modulation:

http://www.autonerdz.com/cgi/yabb2/YaBB.pl?num=1202770788

Not external RFI.

Here is your file back at you with some filter.  You can still see the activity there just not as very well.  Pico shows you EVERYTHING if you let it.   ;)

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So, are we saying we should filter alternator ac waveforms?  I would assume we are looking for the basic diode pattern failures that we are all used to seeing.

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So, are we saying we should filter alternator ac waveforms?

No, not at all.  Let Pico show you everything, then filter if desired.  TPS and O2 are prime candidates for filter.

In your capture, it was also not necessary to run the scope at 10 MS/s.  That's way overkill for what you were doing.   ;)