by **Gerry** » Mon Oct 10, 2016 2:48 pm

Hi sba923,

The custom function was created from observation. I have previously created the instantaneous RMS function, and I knew that it would, to some extent, smooth out the pulse burst, and saw that it creates a group of peaks. I then figured that a low pass filter would completely (or almost) smooth the peaks out for me, to give the mark/space equivalent.

This Math channel was a quick implementation, which is often not the best. In this case, I forgot to add you will need to adjust the cutoff frequency of the filter for it to work on significantly different signal frequencies. I'm sure there is a more elegant, effective solution which would not be dependent upon the frequency of the burst (unfortunately the obvious function, ABS{A}, gives a disjointed waveform, and still leaves signal peaks).

There could be a number of reasons why the Math channel doesn't appear on your PC. First of all check that you are using a version of PicoScope 6 that is new enough to be able to read the psdata file created by the latest version. If there is an issue importing the Math functions and the Math channel is not there, you should be able to just create the function on the PC that doesn't have it by typing it in (if you write down what it is). However, you still may not be able to see the resulting waveform due to the next problem.

One of the most common reasons that a Math channel waveform is not visible is that the scaling is defaulting to a wrong value. Unfortunately, when you create a Math channel, the scale used for the amplitude of the function is not normalized according to the expected range (i.e. based upon the function and the input/s that it is applied to). In your case, you can correct this by just comparing the Y-axes for the 2 PC's, and making the adjustment in the Math channel by checking the 'Override automatic range selection' check-box and entering the correct values.

Regards,

Gerry

Gerry

Technical Specialist