- added

git-svn-id: http://moon:8086/svn/matlab/trunk@128 801c6759-fa7c-4059-a304-17956f83a07c
2020-07-23 11:10:12 +00:00
parent 0631c89f10
commit 1f5b0b0570
8 changed files with 288 additions and 1 deletions
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+function [Bp,Ap] = boost3a(fs, fc, bw, gain, P);
+%BOOST - Design a boost filter at given gain, center
+%        frequency fc, bandwidth bw, and sampling rate fs
+%        (default = 1).
+%
+%        Cookbook formulae for audio EQ biquad filter coefficients
+%        by Robert Bristow-Johnson  <rbj@audioimagination.com>
+
+Q = bw/fs;
+
+Bp = zeros(P, 3);
+Ap = zeros(P, 3);
+for p=1:P,
+	kp = IIRCalcQp(p, P);
+	[Bp(p,:),Ap(p,:)] = peaking(fs, fc, kp*Q, gain);
+endfor
+
+B = Bp(1,:);
+A = Ap(1,:);
+if nargout==0
+  close
+  freqz(B,A);
+  title('Boost Frequency Response')
+end
+
+endfunction
+
+function [B,A] = peaking(fs, fc, Q, K)
+	k1=-cos(2*pi*fc/fs);
+	k2=(1-tan(Q/2))/(1+tan(Q/2));
+	Pz = [1 k1*(1+k2) k2]; % define denominator coefficients
+	Qz = [k2 k1*(1+k2) 1]; % define numerator coefficients
+	Num = (Pz*(1+K) + Qz*(1-K))/2;
+	Den = Pz;
+	B = Num;
+	A = Den;
+	
+endfunction
+
+function kp = IIRCalcQp(p, P)
+	kp = 1.0/(2*sin(pi*(2*p-1)/(2*P)));
+	
+endfunction