iircomb (Digital Filter Design Toolkit, MathScript Function)
Owning Class: singlerate
Syntax
[b, a] = iircomb(n, bw)
[b, a] = iircomb(n, bw, ab)
[b, a] = iircomb(n, bw, t)
[b, a] = iircomb(n, bw, ab, t)
Description
Designs an infinite impulse response (IIR) comb filter.
Inputs
Name  Description  
n  Specifies the order of the filter. n is a positive integer.  
bw  Specifies the bandwidth of the filter notch or peak at ab dB. bw is a doubleprecision, floatingpoint number that must fall in the range (0, 2/n).  
ab  Specifies the attenuation, in decibels, that corresponds to the bandwidth bw. ab is a doubleprecision, floatingpoint number greater than zero. The default is 3.0103, which corresponds to a 3 dB bandwidth, a commonly used bandwidth for a filter.  
t  Specifies the type of IIR comb filter you want to design. t is a string that accepts the following values:

Outputs
Name  Description 
b  Returns the numerator of the designed IIR filter. b is a real vector with a length of n+1. 
a  Returns the denominator of the designed IIR filter. a is a real vector with a length of n+1. 
Examples
[b, a] = iircomb(10, 0.001, 3.0103);
fft_mag = abs(fft(b, 16384)./fft(a, 16384));
figure;
plot(0:1/8192:1, fft_mag(1:8193));
[b, a] = iircomb(10, 0.001, 3.0103, 'peak');
fft_mag = abs(fft(b, 16384)./fft(a, 16384));
figure;
plot(0:1/8192:1, fft_mag(1:8193));