Hi Malcolm

Sorry about the confusion with what you were asking

I just skimmed over your post and thought I had sent the relevant info that might help.

I agree with Carl regarding what you are possibly seeing in the primary trace. But, I have noticed that your voltage setting may be also screwing with your waveform.

I would not advise using the auto range.



Also,
In your Cam and Crank capture the timebase you are using and the sample rate you are using means your sample interval will be around 200Us which is probably a bit slow for catching fast frequency signals. There is a good chance you will miss vital information or glitches.



I hope this may help you in the future

Cheers
James