Waveform display issues

Ask any non-NVH related questions about using PicoDiagnostics software here.
Liteace
TwoWaves
TwoWaves
Posts: 238
Joined: Fri Jan 27, 2012 12:25 pm

Waveform display issues

Post by Liteace »

Hi All used my scope today for the 1st time wanted to check MAP and o2 sensor but having a small problem with display, as you can see I cant get a nice neat fine line, blue trace MAP, red trace o2, what am I doing wrong ?

picowave.png
DONT SHOOT YOURSELF IN THE FOOT

GRUSS
TwoWaves
TwoWaves
Posts: 119
Joined: Tue Dec 27, 2011 11:16 pm

Re: Waveform display issues

Post by GRUSS »

Looks as though your capturing quite a bit of interference, try hanging the leads away from the ignition. Turn your sample rate down to loose some of the hairy spider,Slowly adjust the resolution Upwards from 12bit to see if that clears it up. Also try adding a low pass filter to the capture after you have stopped the recording. I'd also lower thetime base to say 10 seconds as well..
HTH

Alan
Pico Staff Member
Pico Staff Member
Posts: 264
Joined: Thu May 25, 2006 8:02 am

Re: Waveform display issues

Post by Alan »

Great advice from Gruss above. Moving the leads away from sources of interference may help a bit but the noise is probably present in the wiring loom of the vehicle due to wires being close together - this is normal. The low pass filter option should remove the noise (filters inside the ECU do the same thing).

I would also up the 1V range used for the 02 up from 1V to 2V as with the noise on top of the near 1V signal its going slightly out of range.

If you are having problems getting the filtering sorted then upload the waveform and one of us will tweak the file for you.

Dave Hill
TwoWaves
TwoWaves
Posts: 63
Joined: Fri Jun 22, 2007 8:15 am

Re: Waveform display issues

Post by Dave Hill »

I tend not to be overly concerned with noisy captures. In the early days of scoping I became a little obsessed with trying to get a super clean signal, like those seen in the "Automotive Pre-set" examples. Real life capturing is seldom so tidy though & now Pico have given us the ability to apply filters to files that we have previously saved, there seems less of a reason to even think about filtering a live capture. In fact you will often limit yourself in doing so.

Just my thoughts.

:D

User avatar
Robski
Advanced User
Advanced User
Posts: 598
Joined: Tue Sep 14, 2010 6:36 pm
Location: Yorkshire

Re: Waveform display issues

Post by Robski »

Agreed...................take the capture............clean up after...............don't worry when capturing live.

Liteace
TwoWaves
TwoWaves
Posts: 238
Joined: Fri Jan 27, 2012 12:25 pm

Re: Waveform display issues

Post by Liteace »

Thanks guys the filter has done the job
DONT SHOOT YOURSELF IN THE FOOT

Liteace
TwoWaves
TwoWaves
Posts: 238
Joined: Fri Jan 27, 2012 12:25 pm

Re: Waveform display issues

Post by Liteace »

So would the filter work on say this waveform:

http://www.picoauto.com/support/post25756.html#p25754

of MAF that Gruss posted,

Sorry for all the question, Im have been using various scopes over the years and never seen a waveform like these, they have all been just a line
DONT SHOOT YOURSELF IN THE FOOT

User avatar
Robski
Advanced User
Advanced User
Posts: 598
Joined: Tue Sep 14, 2010 6:36 pm
Location: Yorkshire

Re: Waveform display issues

Post by Robski »

Yes a filter will work,you just have to be careful you don't filter too much.

Liteace
TwoWaves
TwoWaves
Posts: 238
Joined: Fri Jan 27, 2012 12:25 pm

Re: Waveform display issues

Post by Liteace »

Thanks for the help guy's, all the scopes Ive had over the years have never had a filter, they've just displayed a line so that through me a bit

Thanks
DONT SHOOT YOURSELF IN THE FOOT

User avatar
Robski
Advanced User
Advanced User
Posts: 598
Joined: Tue Sep 14, 2010 6:36 pm
Location: Yorkshire

Re: Waveform display issues

Post by Robski »

It also depends how much sample rate you have set, the higher the rate the more dots drawn.

Post Reply