I am strugling with a question that I hope someone can help me with.
I am recording single molecule events which I detect is picoampere square deflections.
I wish to use as gentle low-pass bessel filtering as possible.
The lowest filter settings my amplifier allow are 10 kHz and 100 kHz, and my digitizer have a maximal sampling rate of 500 kHz. I am afraid of corrupting my signal to much, but do not have the intuitive understanding of sampling and filtering to know if I am doing something wrong. Here is what I do:
I filter the signal with a 100 kHz bessel filter and digitize it with a 500 kHz sampling rate. I then wish to filter my digitized data with a 35 kHz digital filter.
Would this mess up my data? I hear people say that I am on safe ground if i sample at appropximatly 10x my filter settings, but I get to this 'safe zone' only when I do the post-sampling digital filtering. So I guess what I realy do not understand is if the order of filtering, sampling, filtering does something nasty to the data.
I hope I was able to communicate my question clear enough.
Thank you very much, Best regards, Michael