how extract spectr signal a modulated signal amplitude ??

I need a program that extracts the spectr of an amplitude modulated signal

Answer 1

[Wayne King]

The spectrum of an amplitude-modulated signal is simply its Fourier transform. Unless you are asking about how to extract the envelope of an amplitude-modulated signal. That you can do using the Hilbert transform (require Signal Processing Toolbox)

 Fs = 10000;
 t = 0:1/Fs:1;
 x = [1+cos(2*pi*10*t)].*cos(2*pi*1000*t);
 y = hilbert(x);
 plot(t(1:2000),x(1:2000)); hold on;
 plot(t(1:2000),abs(y(1:2000)),'r','linewidth',2);
 plot(t(1:2000),-abs(y(1:2000)),'r','linewidth',2);

[lahssan]

thank you rather I need real or complex cepstrum signal to signal.

[Wayne King]

Are you sure you don't mean you want the spectral envelope?