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Member
Posts: 2

# Reversing counting direction in frequency measurement (large range, two counters)

Hello there,

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!

Michael

Active Participant
Posts: 433

# Re: Reversing counting direction in frequency measurement (large range, two counters)

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?

Best regrds

Andrea P.

Member
Posts: 2

# Re: Reversing counting direction in frequency measurement (large range, two counters)

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.

Thanks!!

Active Participant
Posts: 433

# Re: Reversing counting direction in frequency measurement (large range, two counters)

Hi,

now I understood. No, it isn t possible with frequency measurement. You would need to use anoterh counter.

Best regards

Andrea