I'm doing a pulse count on a fairly noisy square wave signal with a cDAQ-9172 and a 9401 module. The built-in filter seems to work very well at a minimum pulse width of about 6 microseconds. However, I was wondering if the filter is capable of rejecting "inverse pulses" as well. In other words, if the signal is high and some noise causes it to drop to low and come back to high in less than 6 microseconds, will the filter reject that? If not, the counter would see two pulses separated by a very short time, which, of course, is inaccurate.
Based on my results so far, either the filter does reject these "inverse pulses" or there aren't many that drop below the threshold. Even so, it's important that these measurements be accurate basically to the exact number, so it would put me at ease if somebody knew the answer to this question.
If my wording was a little unclear, I'd be happy to try to rephrase it or maybe include a sketch of precisely what I'm talking about.
