Thank you, Steve, for such a detailed and helpful answer!

I'll need to read, think and then have another session on the rig before I can come back, but thank yiou again for the offer!
John

20181027 1000rpm.psdata Hello, newbie here! I'm a engineering student studying crankshaft vibration, using a Picoscope 2204. I have a toothed wheel on the crank nose and an inductive sensor, that shows a nice raw trace, but the frequency analysis is as noisy as - a noisy thing! Please see picture. ...