hello!
I'm using ni usb-6002 to read voltage signal. The signal comes from a feed-horn. Then it was processed to normal DC voltage(frequency downconversion, filtering, envelope detection) that ni usb-6002 can read. The vi I'm using looks like this.
I do not have the usb-6002 attached to my computer when I took this picture but as you can see it's pretty simple. I set the samples to read to 50 and I use the RSE mode. Then I save the data to a TDMS file. I found a matlab script that could convert tdms file to m file so that I could edit the data in matlab.
I then plot the data in matlab. The raw data looks like this
Through some previous tests and measurements I was expecting the data to be around 0.9 - 1. However, as you can see in the plot, there are a lot of spikes(the ones at about 16:00 and 18:30 are just fluctuations on the actual signal so these ones are good).
So what did I do wrong? Should I lower the sampling rate or samples to read(I am trying to maintain the sampling rate at 50hz)? Or is it just because there's too much environmental noise and these spikes cannot be eliminated?