Added a LFM matlab script testbench to validate FrFT DPW

codegen_fracFdpw/TBc_fracFdpwLFM.m

@@ -0,0 +1,149 @@
+%% Test fracF_dpw using a physical LFM
+%
+% Parameters chosen to match previous FrFT validation work:
+%
+%   Fs   = 512 MHz
+%   T    = 1 us
+%   B    = 64 MHz
+%
+% Matched FrFT order:
+%
+%   a = -(2/pi)*atan(Fs/(beta*T))
+%
+% where:
+%
+%   beta = B/T
+%
+% Notes:
+%   - FFT is computed on the original (non-interpolated) signal.
+%   - FrFT is computed on the interpolated signal.
+%   - Power spectra are averaged across the entire DPW.
+
+clear
+clc
+close all
+
+%% Signal parameters
+
+N       = 512;
+Nframes = 64;
+
+Fs = single(512e6);
+T  = single(1e-6);
+
+B    = single(64e6);
+beta = B/T;
+
+%% Time axis
+
+t = single((-N/2:N/2-1).') / Fs;
+
+%% Generate LFM
+
+x = exp(1j*pi*beta*(t.^2));
+
+x = complex(single(real(x)), ...
+            single(imag(x)));
+
+%% Create DPW
+
+X = repmat(x,1,Nframes);
+
+%% Interpolate exactly as Simulink
+
+halfbandInterp = dsp.FIRHalfbandInterpolator;
+
+Xint = halfbandInterp(X);
+
+%% Matched FrFT order
+
+aMatch = single(-(2/pi)*atan(Fs/(beta*T)));
+
+fprintf('\n');
+fprintf('Fs      = %.3f MHz\n',double(Fs)/1e6);
+fprintf('T       = %.3f us\n',double(T)*1e6);
+fprintf('B       = %.3f MHz\n',double(B)/1e6);
+fprintf('aMatch  = %.6f\n',double(aMatch));
+
+%% FFT reference
+%
+% FFT detector operates on the original non-interpolated signal.
+
+FFTref = fftshift(fft(X,[],1),1)/N;
+
+%% FrFT
+%
+% FrFT detector operates on the interpolated signal.
+
+[Achirp,H,Cchirp,Aa] = fracF_init(aMatch);
+
+Ffrft = fracF_dpw( ...
+    Xint,...
+    Achirp,...
+    H,...
+    Cchirp,...
+    Aa);
+
+%% Mean power spectrum across the DPW
+
+Pfft = mean(abs(FFTref).^2,2);
+
+Pfrft = mean(abs(Ffrft).^2,2);
+
+%% Peak comparison
+
+peakFFT  = max(Pfft);
+peakFrFT = max(Pfrft);
+
+gain_dB = 10*log10(double(peakFrFT/peakFFT));
+
+fprintf('\n');
+fprintf('FFT peak power       : %.6f\n',double(peakFFT));
+fprintf('FrFT peak power      : %.6f\n',double(peakFrFT));
+fprintf('Processing gain      : %.3f dB\n',gain_dB);
+
+%% Normalize spectra for display
+
+Pfft_dB = 10*log10(Pfft/max(Pfft));
+
+Pfrft_dB = 10*log10(Pfrft/max(Pfrft));
+
+%% Display averaged spectra
+
+figure
+
+subplot(2,1,1)
+
+plot(Pfft_dB)
+
+grid on
+
+ylim([-60 5])
+
+title('FFT Mean Power Spectrum')
+xlabel('FFT Bin')
+ylabel('Power (dB)')
+
+subplot(2,1,2)
+
+plot(Pfrft_dB)
+
+grid on
+
+ylim([-60 5])
+
+title(sprintf('FrFT Mean Power Spectrum (a = %.6f)', ...
+      double(aMatch)))
+
+xlabel('FrFT Bin')
+ylabel('Power (dB)')
+
+%% Report peak locations
+
+[~,idxFFT]  = max(Pfft);
+[~,idxFrFT] = max(Pfrft);
+
+fprintf('\n');
+fprintf('FFT peak bin        : %d\n',idxFFT);
+fprintf('FrFT peak bin       : %d\n',idxFrFT);
+fprintf('\n');

codegen_fracFdpw/TBc_fracFdpwNO.m

@@ -12,7 +12,7 @@ clc
 
 %% Test parameters
 
-a = single(0.999);
+a = single(1);
 
 N       = 1024;
 Nframes = 1024;

resources/project/SDMLmaWG7GHkKoV_kJ80kV-luys/Doi5RFBzLXa6WtYn0DqckQqKRLQp.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Info location="TBc_fracFdpwLFM.m" type="File"/>

resources/project/SDMLmaWG7GHkKoV_kJ80kV-luys/rEvooC0-TWPmhyjb2otHax51pGId.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Info>
+    <Category UUID="FileClassCategory">
+        <Label UUID="design"/>
+    </Category>
+</Info>

resources/project/SDMLmaWG7GHkKoV_kJ80kV-luys/rEvooC0-TWPmhyjb2otHax51pGIp.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Info location="TBc_fracFdpwNO.m" type="File"/>

resources/project/SDMLmaWG7GHkKoV_kJ80kV-luys/rFgbE7J0q1IfyjFFVSXP14Sbh30p.xml

@@ -1,2 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<Info location="TBc_fracFdpw.m" type="File"/>