gsignal (version 0.3-1)

cl2bp: Constrained L2 bandpass FIR filter design

Description

Constrained least square band-pass FIR filter design without specified transition bands.

Usage

cl2bp(m = 30, w1, w2, up, lo, L = 2048)

Arguments

m

degree of cosine polynomial, resulting in a filter of length 2 * m + 1. Must be an even number. Default: 30.

w1, w2

bandpass filter cutoffs in the range 0 <= w1 < w2 <= pi, where pi is the Nyquist frequency.

up

vector of 3 upper bounds for c(stopband1, passband, stopband2).

lo

vector of 3 lower bounds for c(stopband1, passband, stopband2).

L

search grid size; larger values may improve accuracy, but greatly increase calculation time. Default: 2048, maximum: 1e6.

Value

The FIR filter coefficients, a vector of length 2 * m + 1, of class Ma.

Details

This is a fast implementation of the algorithm cited below. Compared to remez, it offers implicit specification of transition bands, a higher likelihood of convergence, and an error criterion combining features of both L2 and Chebyshev approaches

References

Selesnick, I.W., Lang, M., and Burrus, C.S. (1998) A modified algorithm for constrained least square design of multiband FIR filters without specified transition bands. IEEE Trans. on Signal Processing, 46(2), 497-501. https://www.ece.rice.edu/dsp/software/cl2.shtml

See Also

Ma, filter, remez

Examples

# NOT RUN {
w1 <- 0.3 * pi
w2 <- 0.6 * pi
up <- c(0.02, 1.02, 0.02)
lo <- c(-0.02, 0.98, -0.02)
h  <- cl2bp(30, w1, w2, up, lo, 2^11)
freqz(h)

# }