gnuplot_binary ("/opt/local/bin/gnuplot")
%load -ascii tek0005CH1.csv 

% Decide where the two samples are
T_signal = 500000:504000; % signal + noise
T_noise = 400000:404000; % noise only 

% Find the sampling period, assuming it is constant 
T_samp = tek0005CH1(2, 1) - tek0005CH1(1, 1);

wavwrite("output.wav", tek0005CH1(:,2), 1/T_samp, 16 );

figure(1);
subplot(2,1,1);
plot(T_signal, tek0005CH1(T_signal, 2))
title('Signal and Noise Time Domain');
subplot(2,1,2);
plot(T_noise, tek0005CH1(T_noise, 2))
print -djpg signal_noise_time_domain.jpg

fft_signal = fft(tek0005CH1(T_signal, 2));
fft_noise = fft(tek0005CH1(T_noise, 2));
fft_length = size(fft_signal,1)+1;
BANDDIV = 2.5; % take this fraction of the bandwidth 
fft_domain = 1:(fft_length/2/BANDDIV);
fft_freq = linspace(1, 1/T_samp/2/BANDDIV, fft_length/2/BANDDIV);

figure(2);
subplot(2,1,1);
semilogy(fft_freq, abs(fft_signal(fft_domain) ));
title('Signal and Noise Energy Spectrum');
subplot(2,1,2);
semilogy(fft_freq, abs(fft_noise(fft_domain) ));
print -djpg signal_noise_freq_domain.jpg