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% cohpsk_demod_plot.m
% David Rowe May 2015
%
% Plot Octave outputs from cohpsk_demod, c2dec, to visualise what's going on
% when errors hit the system
#{
$ ./cohpsk_get_test_bits - 5600 | ./cohpsk_mod - - | ./ch - - --No -40 | ./cohpsk_demod - - -o cohpsk_demod.txt | ./cohpsk_put_test_bits -
octave> cohpsk_demod_plot("../build_linux/src/cohpsk_demod.txt")
#}
function cohpsk_demod_plot(fn)
Nc=7; Nd=2; Ns=6;
load(fn);
Ncf = 100; % number of codec frames to plot
Nmf = Ncf/2; % number of modem frames to plot
Nms = Nmf*Ns; % number of modem symbols to plot
figure(1)
clf;
% plot combined signals to show diversity gains
combined = rx_symb_log_c(:,1:Nc);
for d=2:Nd
combined += rx_symb_log_c(:, (d-1)*Nc+1:d*Nc);
end
plot(combined*exp(j*pi/4)/sqrt(Nd),'+')
title('Scatter');
axis([-2 2 -2 2])
figure(2)
clf;
subplot(211)
plot(rx_phi_log_c(1:Nms,:))
title('phase')
axis([1 Nms -pi pi])
subplot(212)
plot(rx_amp_log_c(1:Nms,:))
title('amplitude')
axis([1 Nms 0 1])
figure(3)
subplot(211)
plot(rx_timing_log_c)
title('rx timing');
subplot(212)
stem(ratio_log_c)
title('Sync ratio');
figure(4)
plot(f_est_log_c - 1500)
title('freq offset est');
axis([1 Nmf -50 50])
figure(5)
y = 1:Nms;
x = 1:Nc*Nd;
z = 20*log10(rx_amp_log_c(1:Nms,:));
mesh(x,y,z);
grid
title('Channel Amplitude dB');
a = min(min(z));
b = max(max(z));
axis([1 Nc*Nd 1 Nms a b])
end
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