Potentiometer Gap and Filter Ringing

[depressed]

We have a potentiometer wiper (+6V at one end and -6V at the other) that revolves 360 degrees around the pot.  DASYLab is set up to look for noise in the system and picks up the gap in the potentiometer.  DASYLab interprets the change from -6V to +6V as a large spike (appears as a sawtooth pattern) and fails our noise test.  We tried to use a relay to "blank out" the gap but it was still picked up as a sudden change in voltage, thus creating a spike.  There is a hi pass filter in place after the sawtooth signal.  Is there a way that the universal filters can help?

[TomRizzo]

I would use a trigger not to monitor the signal when is above 5.95 Volts and below -5.95 Volts so that the system will not monitor it.

It would be very difficult to filter an infinite value as per the moment you go from 6 to -6.

[depressed]

We have tried something like this before.  The problem is that when it goes into the filter afterwards, the filter sees the difference in the voltage and causes a spike.  We used a trigger and a relay to close the line but the butterworth filter sees the large dV/dt change.  DASYLab is "aware" of the voltage data even though it is not looking at it.  That is where the problem comes in.  We need a way for the filter to accept the change in voltage.  Maybe the FIR filter could be useful?

[TomRizzo]

You could try with an FIR filter but, in my opinion, yu need to build your worksheet to only monitor your test through the working area of your potentiometer.  Than can be done without to many problems.  As example, you could 0 the error trigering while in the wrong range.

We do something similar all the time.