- refactored

common/filter/digital/fir/cic_filter.m

@@ -0,0 +1,30 @@
+function [y, gain] = cic_filter(R, M, N, x)
+% [y, gain] = cic_filter(R, M, N, x)
+
+a_i = [1 -1];
+b_i = 1;
+
+a_c = 1;
+b_c = [1 zeros(1, M-1) -1];
+
+gain = (M*R)^N
+k_i = 1/(M*R);
+
+i_out = x;
+
+% Integrator
+for i=1:N,
+    i_out = k_i*filter(b_i, a_i, i_out);
+end;
+
+% Decimate
+c_out = i_out(R:R:length(i_out));
+
+% Comb
+for i=1:N,
+    c_out = filter(b_c, a_c, c_out);
+end;
+
+
+y = c_out;
+

common/filter/digital/fir/cic_plot.m

@@ -0,0 +1,23 @@
+function cic_plot(M, N, R)
+% cic_plot(M, N, R)
+
+ns = 1000;
+f = 2*(1:ns)/ns;
+H = abs(sin(pi*M.*f)./sin(pi.*f/R)).^N;
+
+subplot(2,1,1)
+plot(f,H); 
+xlabel('f / fs');
+ylabel('G');
+grid;
+
+Gain = (R*M)^N
+BitGrowth = ceil(N*log2(R*M))
+
+subplot(2,1,2)
+plot(f,20*log10(H/Gain));
+xlabel('f / fs');
+ylabel('A/dB');
+grid;
+
+Atten_fs2 = 20*log10(H(ns/2)/Gain)

common/filter/digital/iir/coef.m

@@ -0,0 +1,71 @@
+% COEF generiert IIR-Tiefpass Koeffizienten für geradzahlige Ordnung
+% [b,a] = coef(fa,fg,Q,N)
+%
+% fa   : Abtastfrequenz [Hz]
+% fg   : Grenzfrequenz  [Hz]  fg <= fa/2
+% Q    : Polgüte (Q=1.0 für Butterworth)
+% N    : Filterordnung (durch zwei teilbar)
+% Type : 'Lowpass', 'Highpass', 'Bandpass', 'Bandstop'
+%
+function [b,a] = coef(fa,fg,Q,N,Type)
+
+if (rem(N,2) > 0)
+  error('Filterordnung muss z.Zt. noch durch zwei teilbar sein!');
+end;
+
+if (strcmp(Type,'Bandstop'))
+  TF = 4;
+end;
+
+TF
+sn = sin(2*pi*fg/fa);
+cs = cos(2*pi*fg/fa);
+ak = ones(N/2,3);
+bk = ones(N/2,3);
+a  = 1;
+b  = 1;
+
+if (strcmp(Type,'Lowpass'))
+  for n = 1:N/2,
+    Qp      = 1/(2*sin(pi*(n-0.5)/N))
+    alpha   = sn/(2*Q*Qp);
+    a0      = 1+alpha;
+    ak(n,2) = -2*cs/a0;
+    ak(n,3) = (1-alpha)/a0;
+    bk(n,1) = 0.5*(1-cs)/a0;
+    bk(n,2) = (1-cs)/a0;
+    bk(n,3) = 0.5*(1-cs)/a0;
+    a       = conv(a,ak(n,(1:3)));
+    b       = conv(b,bk(n,(1:3)));
+  end;
+end;
+
+if (strcmp(Type,'Highpass'))
+  for n = 1:N/2,
+    Qp      = 1/(2*sin(pi*(n-0.5)/N))
+    alpha   = sn/(2*Q*Qp);
+    a0      = 1+alpha;
+    ak(n,2) = -2*cs/a0;
+    ak(n,3) = (1-alpha)/a0;
+    bk(n,1) = 0.5*(1+cs)/a0;
+    bk(n,2) = -(1+cs)/a0;
+    bk(n,3) = 0.5*(1+cs)/a0;
+    a       = conv(a,ak(n,(1:3)));
+    b       = conv(b,bk(n,(1:3)));
+  end;
+end;
+
+if (strcmp(Type,'Bandpass'))
+  for n = 1:N/2,
+    Qp      = 1/(2*sin(pi*(n-0.5)/N))
+    alpha   = sn/(2*Q*Qp);
+    a0      = 1+alpha;
+    ak(n,2) = -2*cs/a0;
+    ak(n,3) = (1-alpha)/a0;
+    bk(n,1) = alpha/a0;
+    bk(n,2) = 0;
+    bk(n,3) = -alpha/a0;
+    a       = conv(a,ak(n,(1:3)));
+    b       = conv(b,bk(n,(1:3)));
+  end;
+end;

common/filter/digital/iir/iirtp.m

@@ -0,0 +1,13 @@
+% IIR-Tiefpass
+% y = iirtp(fa,fg,Q,N,x)
+%
+% fa : Abtastfrequenz [Hz]
+% fg : Grenzfrequenz  [Hz]  fg <= fa/2
+% Q  : Polgüte (Resonanz)
+% N  : Filterordnung (durch zwei teilbar)
+% x  : Eingangssignal
+function y = iirtp(fa,fg,Q,N,x)
+
+[b,a] = iirtpc(fa,fg,Q,N);
+
+y = filter(b,a,x);

common/filter/digital/iir/iirtp2.m

@@ -0,0 +1,13 @@
+% IIR-Tiefpass
+% [y,zf] = iirtp2(fa,fg,Q,N,x,zi)
+%
+% fa : Abtastfrequenz [Hz]
+% fg : Grenzfrequenz  [Hz]  fg <= fa/2
+% Q  : Polgüte (Resonanz)
+% N  : Filterordnung (durch zwei teilbar)
+% x  : Eingangssignal
+function [y,zf] = iirtp(fa,fg,Q,N,x,zi)
+
+[b,a] = iirtpc(fa,fg,Q,N);
+
+[y,zf] = filter(b,a,x,zi);

common/filter/digital/iir/iirtpc.m

@@ -0,0 +1,33 @@
+% IIRTPC generiert IIR-Tiefpass Koeffizienten für geradzahlige Ordnung
+% [b,a] = iirtpc(fa,fg,Q,N)
+%
+% fa : Abtastfrequenz [Hz]
+% fg : Grenzfrequenz  [Hz]  fg <= fa/2
+% Q  : Polgüte (Resonanz)
+% N  : Filterordnung (durch zwei teilbar)
+%
+function [b,a] = iirtpc(fa,fg,Q,N)
+
+if (rem(N,2) > 0)
+  error('Filterordnung muss z.Zt. noch durch zwei teilbar sein!');
+end;
+
+sn = sin(2*pi*fg/fa);
+cs = cos(2*pi*fg/fa);
+ak = ones(N/2,3);
+bk = ones(N/2,3);
+a  = 1;
+b  = 1;
+
+for n = 1:N/2,
+  Qp      = 1/(2*sin(pi*(n-0.5)/N));
+  alpha   = sn/(2*Q*Qp);
+  a0      = 1+alpha;
+  ak(n,2) = -2*cs/a0;
+  ak(n,3) = (1-alpha)/a0;
+  bk(n,1) = 0.5*(1-cs)/a0;
+  bk(n,2) = (1-cs)/a0;
+  bk(n,3) = 0.5*(1-cs)/a0;
+  a       = conv(a,ak(n,(1:3)));
+  b       = conv(b,bk(n,(1:3)));
+end;

common/filter/digital/iir/undcc.m

@@ -0,0 +1,27 @@
+% Erzeugt Filterkoeffizienten für FIR-Filter zur Eliminierung des Gleichanteils
+% -----------------------------------------------------------------------------
+%
+% Aufruf
+% Function [coeff] = undcc(N)
+%
+% Parameter:
+% N     : Bestimmt Grösse des Koeffizientenvektors
+%
+% Rückgabewerte:
+% coeff : Koeffizientenvektor, Länge N
+
+% -----------------------------------------------------------------------------
+% Datum : 26.07.2001
+% Autor : Jens Ahrensfeld
+% Thema : Diplomarbeit
+% Datei : undcc.m
+% Benötigte Dateien: 
+%
+% -----------------------------------------------------------------------------
+function [coeff] = undcc(N)
+
+% Ansatz: y = x - arith. Mittelwert(x)
+coeff = [1.0-1/N ; -1/N*ones(N-1,1)];
+
+% -----------------------------------------------------------------------------
+% Ende undcc.m