Jumpy hall signal

[Nathan]

What would cause a hall signal to jump up and down on all 3 phases ? i.e all 3 phases have the same not clean hall pulses.

Picture of oscilloscope view attached.

 

[Skalabala]

What are you using for their power source?

 

[Nathan]

A power supply for testing them. I was having problems getting the sinewave controller to autoidentify motor hence i did this test with power supply to motor on oscilloscope. How to fix this ?

 

[jk1]

If its like that on all 3 hall sensors is it some type of noise? not sure if other have seen this do you need to add some type of noise filters on the hall wires ?

 

[Nathan]

Yes on all 3 phases, how can I fix this as it wont autoidentify the halls ?

 

[docw009]

Do you have a two or four channel scope so you can watch two or all three of the sensors outputs to see if there is a relationship between these glitches?

Years ago, I was vexed with something like this in an automotive cam position sensor (also Hall effect) on my car. Two overlapping rectangular waves were glitching each other at higher RPM. I could also see it on my scope but couldn't get rid of it. Turned out to be real simple. Loose ground nut in wire harness.

I would be surprised if a ground is the case here, but you said all three do this, so maybe looking at more than one will yield some clues.