pkg load signal;

[y, fs] = audioread("modulator22.wav");
range = 0:1/fs:(1/fs)*(size(y)-1);
#plot (range, y);
#xlabel ("Time (s)");
#ylabel ("Amplitude (arbitrary unit)");
b=fir1(30,1000/(fs/2));
yfiltered=filter(b,1,y);

a=butter(8,1000/(fs/2));
ybuttered=filter(a,1,y);

[h,w]=freqz(a,1)
freqz_plot(w,h);





newfsdwn = 4000;
n=fs/newfsdwn;
ydwn = downsample(ybuttered, n);
audiowrite("modifiedwithdownsample.wav",ydwn,newfsdwn);

ydec = decimate(ybuttered,6);
fsndec = fs*size(ydec)/size(y);
audiowrite("modifiedwithdecimate.wav",ydec,fsndec);





y_min = find(range >= 0,1);
y_max = find(range <= 0.3,1,"last");
yf= y(y_min:y_max);

[power, duration] = frequencySpectrum(ybuttered, fs, true);



spectrogram(ybuttered, fs, 5, 30);