I have some (well lots) of data signals which are measurements of current pulses. The current pulses are the result of spark breakdowns (20 kV + 700 pF capacitor so quite energetic) and my problem is that noise, and displacement current signals are clouding the underlying current pulse.
The noise and the displacement current signals are quite high frequency. The actual pulse, is much lower so I am wanting a low pass filter. I use Origin Labs and in there I can apply a low pass FFT filter and I find that for the most part, a cut off of about 7 MHz does the trick for some of the more well defined pulses, sometimes I have to use something higher like 15 MHz.
I have a lot of measurements and would like to speed this process up by getting Matlab to do it for me.
The data files should all be the same length and all the same resolution (A cursory looks says each file has 9900 points, with a time step of 4e-10 seconds, so about 4 uS of data).
I just don't have a clue where to start with this in Matlab. I don't need anything fancy, I merely want to pull out an approximate value of the current. I have tried something simple like performing the FFT and then making all values above a certain frequency = 0 then doing the inverse FFT but that appears to do nothing at all!
I can't post a picture of the signal, apparently I need some reputation on here or something first. But I may be able to host it on my Flickr page if needs be.