FIR Filters

FIR——Finite impulse response, finite impulse response.

FIR filter, also known as non-recursive filter, convolution filter, the current output of the filter is related to the current input value and the previous input value. The formula is as follows:

  x is the input sequence, y is the filtered output sequence, and h is the FIR filter coefficient.

IIR Filters

IIR——Infinite impulse response, infinite impulse response.

IIR filter, also known as recursive filter, the current output of the filter is not only related to the current input value, the previous input value, but also the previous output value. Therefore, the impulse response of IIR filter tends to 0, but never 0, which is one of the differences from FIR filter.

The formula is as follows:

The following is confirmed by experiments: