Many data-acquisiton boards are recommended to use anti-aliasing filters between the analog inputs and the ADC. Here what I understand from anti-aliasing: If one has a DC like signal and the freq. of interests of the signal is not more than 10Hz one can use an RC low pass filter with a 20Hz cutoff freq.
But what if the signal is a pulse? I want to make an RC aliasing filter for pulse frequencies changing between minimum 3Hz up to 500Hz. My sampling freq is 4kHz. In this case, one might use an RC filter with a cutoff freq of 1kHz but this could effect the rising and falling edge shapes significantly. I still want the pulse shape as sharp good as possible.
Is there a rule of thumb for an RC antialasing filter if the input is a pulse in daq systems?