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So you have two single tones coming from ADC; one at 1Hz, and one at 1KHz and you want to filter off the 1Khz and pass the 1 Hz
You haven't said anything about Fs of signal itself. You have chosen Fs of 1KHz first then FS of 5KHz. You can't just pick a value. Your Fs must be that of input signal and should be same as ADC Fs unless you have done downsampling which I doubt.
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The Fs of signal itself is 25MHZ .
This example is for testing the function of the FIR IP filter , and I want to know how to make a low-pass FIR IP filter with high sampling frequency signal ?
thanks a lot !!!