06-12-2012 06:58 AM
is it possible to use the Counter B input (USB 6210) to reverse the counting direction periodically (for a dark count substraction) while performing a frequency measurement using the two counter, large range methode? Or is reversing only possible in edge-counting application since what matters are the active edges the counter input receives?
Thanks a lot!
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06-13-2012 05:02 AM
I would say that it is only possble in the case of edge counting.
I don´t really understand how it should be used in a frequency meaurement.
could you exlain it better maybe with a concrete example?
06-13-2012 05:50 AM
A few words concerning the large range, two counter frequency measurement: Counter 1 is fed with the frequency to measure and outputs a pulse with a duration of N input pulses. This pulse width T is measured by the second counter giving the desired frequency as f = N/T.
My idea was to directly subtract the dark count (or dark frequency if you will) by changing the counting direction of Counter 1 by applying a signal to the Counter 1 B input. This would lead to the real frequency without any dark counts. That means that my question boils down to whether the pulse generation of Counter 1 is sensitive to the applied signal at Counter 1 B input or not.
If not I would simply need another counter but it would be good to know in advance since I can't check it.
06-14-2012 04:51 AM
now I understood. No, it isn t possible with frequency measurement. You would need to use anoterh counter.