fir2

B = fir2(N, F, M)
B = fir2(N, F, M, GRID_N)
B = fir1(N, F, M, GRID_N, RAMP_N)
B = fir1(N, F, M, GRID_N, RAMP_N, WINDOW)

Parameters

N:

Integer

F, M:

Vector

Description

Produce an order N FIR filter with arbitrary frequency response M over frequency bands F, returning the N+1 filter coefficients in B. The vector F specifies the frequency band edges of the filter response and M specifies the magnitude response at each frequency.

The vector F must be nondecreasing over the range [0,1], and the first and last elements must be 0 and 1, respectively. A discontinuous jump in the frequency response can be specified by duplicating a band edge in F with different values in M.

The resolution over which the frequency response is evaluated can be controlled with the GRID_N argument. The default is 512 or the next larger power of 2 greater than the filter length.

The band transition width for discontinuities can be controlled with the RAMP_N argument. The default is GRID_N/25. Larger values will result in wider band transitions but better stopband rejection.

An optional shaping WINDOW can be given as a vector with length N+1. If not specified, a Hamming window of length N+1 is used.

Examples