1 files changed, 0 insertions, 72 deletions
diff --git a/octave/phase_noise.m b/octave/phase_noise.m
deleted file mode 100644
index 37e933c..0000000
--- a/octave/phase_noise.m
+++ /dev/null
@@ -1,72 +0,0 @@
-% phase_noise.m
-% David Nov 2019
-
-% Close-in look at phase noise.  Feed in a off-air sample file of a
-% sine wave, extracts the phase noise contour and returns the Doppler
-% spreading function that can be used to model the channel in
-% simulations
-
-function spread_FsHz = phase_noise(file_name)
-  Fs = 8000;
-  s = load_raw(file_name);
-  % skip past wave header
-  s = [zeros(256,1); s(256:end)];
-  S = abs(fft(s(1:Fs).*hanning(Fs)));
-  [mx mx_bin] = max(S);
-  ftone = mx_bin-1;
-  
-  figure(1); clf;
-  plot(20*log10(S(1:Fs/2)))
-  title('Input Spectrum');
-  
-  % downshift to baseband and LPF.  We just want the sinusoid with as little
-  % additive AWGN noise as possible
-  sbb = s' .* exp(-j*(1:length(s))*2*pi*ftone/Fs);
-  [b a] = cheby1(4, 1, 20/Fs);
-  sbb_lpf = filter(b,a,sbb);
-
-  spread_fsHz = sbb_lpf;
-  
-  % estimate and remove fine freq offset, and HF phase noise
-  
-  st = Fs; en = 20*Fs;
-  phase = unwrap(angle(sbb_lpf(st:en)));
-  fine_freq = mean(phase(2:end) - phase(1:end-1));
-  sbb_lpf_fine = sbb_lpf .* exp(-j*(1:length(sbb_lpf))*fine_freq);
-  phase = unwrap(angle(sbb_lpf_fine(st:en)));
-
-  printf("length: %3.2fs freq: %5.1f\n", length(s)/Fs, ftone+fine_freq*Fs/(2*pi));
-
-  figure(2); clf;
-  plot3((st:en)/Fs, real(sbb_lpf_fine(st:en)),imag(sbb_lpf_fine(st:en)))
-  title('Polar phase trajectory');
-
-  figure(3); clf;
-  S2 = fftshift(fft(sbb_lpf_fine(Fs:Fs*11)));
-  [mx mx_bin] = max(abs(S2));
-  S2dB = 20*log10(abs(S2));
-  mxdB = 10*ceil(max(S2dB)/10);
-  x = -10:0.1:10;
-  plot(x,S2dB(mx_bin-100:mx_bin+100));
-  axis([-10 10 mxdB-40 mxdB])
-  title('Close in Phase Noise Spectrum');
-  xlabel('Freq (Hz)');
-  grid;
-  
-  figure(5); clf;
-  t = (st:en)/Fs;
-  plot(t, phase,'b;phase;');
-  title('Unwrapped Phase');
-  xlabel('Time (sec)')
-  ylabel('Phase (radians)')
-  
-  figure(6); clf;
-  beta = 0.00001;
-  rate_of_change_Hz = filter(beta, [1 -(1-beta)],phase(2:end) - phase(1:end-1))*Fs/pi;
-  plot(t(2:end), rate_of_change_Hz)
-  title('Rate of change of phase (Hz)');
-  xlabel('Time (sec)')
-  ylabel('Freq (Hz)')
-
-  spread_FsHz = sbb_lpf_fine/std(sbb_lpf_fine);
-end