octave script to plot modem states from ofdm_demod c program

git-svn-id: https://svn.code.sf.net/p/freetel/code@3464 01035d8c-6547-0410-b346-abe4f91aad63

diff --git a/codec2-dev/octave/ofdm_demod_c.m b/codec2-dev/octave/ofdm_demod_c.m
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+% ofdm_demod_c.m
+% David Rowe April 2018
+%
+% Plots data from The C OFDM demodulator ofdm_demod, in similar format to
+% plots from Octave OFDM demodulator ofdm_rx.m
+%
+% Useful for of line analysis of a demod run
+
+function ofdm_demod_c(filename)
+  ofdm_lib;
+  more off;
+
+  % init modem
+
+  Ts = 0.018; Tcp = 0.002; Rs = 1/Ts; bps = 2; Nc = 17; Ns = 8;
+  states = ofdm_init(bps, Rs, Tcp, Ns, Nc);
+  ofdm_load_const;
+  states.verbose = 0;
+
+  load(filename);
+  
+  figure(1); clf; 
+  plot(rx_np_log_c,'+');
+  mx = 2*max(abs(rx_np_log_c));
+  axis([-mx mx -mx mx]);
+  title('Scatter');
+
+  figure(2); clf;
+  plot(phase_est_pilot_log_c(:,2:Nc),'g+', 'markersize', 5); 
+  title('Phase Est');
+  axis([1 length(phase_est_pilot_log_c) -pi pi]);  
+
+  figure(3); clf;
+  stem(timing_est_log_c)
+  title('Timing Est');
+
+  figure(4); clf;
+  plot(foff_hz_log_c)
+  mx = max(abs(foff_hz_log_c))+1;
+  axis([1 max(length(foff_hz_log_c),2) -mx mx]);
+  title('Fine Freq');
+  ylabel('Hz')
+
+endfunction