Designing a Digital filter from given Transfer function ? Coefficient Calculation ?
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First of all i am not a expert in signal processing i just know the A B C
my question is how to design a filter for my speech codec where i capture speech and compress and tx it over air
so in this event my codec hardware from Texas Instruments TLV320AIC3204 gives me a flexibility to program the filters present in it by the given transfer function
N0 + (N1 * z^-1)
H(z)=---------------------
2^23 - (D1 * z^-1)
Above is an IIR Filter Example
my job is to find out the filter coefficients NO,N1,D1 and fill them up to the codec chip so that i can realize it on an hardware for that i want to take the help of matlab
any way i have some other transfer functions also waiting like biquad filters with a transfer function as below using which i can cascade a LPF and HPF to form a BPF using Biquad blocks
Transfer Function of Each biquad:
N0 + (2* N1 * z^-1 ) + (N2 * z^-2)
H(z)=----------------------------------------
(2^23) - (D1 * z^-1) - (D2 * z^-2)
how to realise this filter in matlab now Help me please
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Answers (3)
Dimka
on 26 Jul 2013
Edited: Dimka
on 26 Jul 2013
Maybe it would be you can help...
clc; clear; close all;
fs = 8e3;
fc = [200 3.5e3];
order = 2;
% b - nominator of complex transfer function; a - denominator;
[b, a] = butter(order, 2*fc/fs, 'bandpass');
disp([{'Numerator'} num2str(b); {'Denominator'} num2str(a)])
%%check
f = fs/2*linspace(0, 1, 8192);
h = freqz(b,a, 8192);
K_dB = 20*log10(abs(h));
plot(f/1e3, K_dB, fc/1e3, [-3 -3], 'or', 'LineWidth', 2); grid on;
xlabel('frequency, kHz'); ylabel('|H|, dB')
axis([min(f/1e3) max(f/1e3) -60 10])
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