Re: What Should be Sampling Frequency Fs in Practical Circui
starfish,
Regarding your first question:
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Steps in determining minimum sampling frequency;
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Calculate, estimate, or measure the amplitudes of frequencies above the maximum frequency of interest.
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Decide what amplitude of aliased components can be tolerated in the sampled signal. This, along with the info determined above will determine the amount of attenuation that must be provided by the anti-aliasing filter at the Nyquist (fs/2) frequency.
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Decide the maximum number of poles you can accept in your anti-aliasing filter. This will be determined by economics, size, etc. Then calculate the frequency at which this filter will provide the minimum acceptable attenuation (determined above). The minimum acceptable sampling frequency is twice this value.
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Regarding your 2nd question:
Yes. A zeroth order hold circuit, followed by a low pass filter will reconstruct the waveform.
Regards,
Kral