Hi Larry, we had a similar issue with our force plate. It was solved when we changed the USB cable that connects the amplifier and the PC with a shielded USB cable. If you still want to use the data you have already collected, we had some success to clean the data using median filtering. Check this MATLAB document if you are interested:

https://www.mathworks.com/help/signa...-a-signal.html

Huseyin