Mysterious noise with MATLAB

[mattgwilson]

Hello,

I'm working on implementing MATLAB code to record from a PicoScope 544A and am having trouble with a huge noise signal. Everything works fine using the PicoScope6 software, but noise is added when I do the same thing (as far as I can tell) in MATLAB.

I'm curious if anyone has ideas on where this might be coming from, since it seems to be a software issue.

My current method for testing is to output a signal and trigger from an external waveform generator straight into the PicoScope (270 kHz burst, 50ms duration, 100mVpp amplitude). With the same sampling rate, ADC conversion of 16 bits, and duration, the matlab signal still is shifted up and has higher frequency noise added.

Any thoughts would be greatly appreciated!

Matt

[tomriis11]

Having the same problem.

[tomriis11]

I figured out the issue. You get significantly different noise levels depending on the range used. I attached photos of a 60 mV sine wave recorded at ranges 100 mV, 500 mV, 2V, 5V. You can see a clear progression where noise increases with range values.