 The frequency response of the FIR filter is drawn like this. It's almost
the same as the IIR filter. (The difference of phase, green line, is caused
by function atan[x]. Don't be careful of that... )
This is a way to make an FIR filter which has almost the same characteristics by using IIR filter's
impulse response, which is not directly related to IIR coefficients.
That's it for this tutorial. Please understand (1)The spectrum of unit impulse is flat and any frequency has the same amount. (2)The spectrum of impulse response is the same as the filter's frequency response. (3)FIR filter's coefficients is the same as its impulse response. (4)Therefore, if you can pick up IIR's impulse response, you can make an FIR filter which has almost the same characteristics.
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