axi_adc_decimate: Added matlab file for filters

library/axi_adc_decimate/m2k_decim.m

@@ -0,0 +1,46 @@
+clear all;
+close all;
+
+decim_rate = 50000;
+
+h_cic = dsp.CICDecimator(decim_rate,1,6);
+gainCIC = (h_cic.DecimationFactor*h_cic.DifferentialDelay)^h_cic.NumSections
+[h1, w1] = h_cic.freqz();
+
+fs = 1;
+fPass = 0.20;
+fStop = 0.50;
+ast = 70;
+
+CICCompDecim = dsp.CICCompensationDecimator(h_cic, ...
+    'DecimationFactor',2,'PassbandFrequency',fPass, ...
+    'StopbandFrequency',fStop,'SampleRate',fs, ...
+    'StopbandAttenuation',ast);
+[h2, w2] = CICCompDecim.freqz();
+CICCompDecim.coeffs()
+
+FC = dsp.FilterCascade(h_cic,CICCompDecim);
+[h3, w3] = FC.freqz();
+
+subplot(311); hold on;
+plot(w1/pi, 20*log10(abs(h1)/gainCIC)); 
+plot(w2/pi, 20*log10(abs(h2))); 
+hold off; grid
+
+subplot(312); plot(w3/pi, 20*log10(abs(h3)/gainCIC)); grid
+
+% M   = 8;   % Decimation factor
+% Fp  = 40;  % Passband-edge frequency
+% Fst = 60;  % Stopband-edge frequency
+% Ap  = 0.1; % Passband peak-to-peak ripple
+% Ast = 80;  % Minimum stopband attenuation
+% Fs  = 800; % Sampling frequency
+% HfdDecim = fdesign.decimator(M,'lowpass',Fp,Fst,Ap,Ast,Fs);
+% HNyqDecim = design(HfdDecim,'kaiserwin','SystemObject', true);
+% 
+% [h4, w4] = freqz(HNyqDecim);
+% subplot(313); plot(w4/pi, 20*log10(abs(h4))); grid
+
+nt = numerictype(1,12,11);
+fdhdltool(h_cic, nt);
+fdhdltool(CICCompDecim, nt)