Cutoff frequency and Sampling Frequency

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sampling frequency

What is the difference of Cutoff Frequency and Sampling Frequency when it comes to sensor Input?
 

cutoff frequency

Let's say, you have: a sensor, an anti-aliasing filter, an A/D.
Theoretically (Nyqist theorem) the cutoff frequency of the anti-aliasing filter should be 1/2 of the sampling frequency. In practice the cutoff frequency should be even smaller; it depends (among other things) on the number of poles in the filter.
 

sampling frequency aliasing

The sampling frequency is related to the mesage signal frequency: fs>=2fm
where fs is the sampling frequency and fm is the high frequency component of the message signal ( information signal)

Cut off freq is the frequency at which the power reduces to half of it's maximum value
 

sinusoidal signal sampling frequency

Hello!

I am proposing you to have cut off frequency for the filter before the SH or ADC according to:

Fcutoff <= Tsampling/4

or even

Fcutoff <= Tsampling/8

Please note that

Fsampling = 4*Fss

guaranteed the band width of the sampler not worse than 3 dB.

You should take into consideration the characteristic of the filter before SH (if any) and the ADC when you calculate the bandwidth of the entire sampling and conversion system.

I think that is a good idea to test your system with sinusoidal signal (SS) and to apply the paper

https://www.ieindia.org/pdf/88/88ET104.pdf
 

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