Amplitude Modulation a .Mp3 file

Hi, I'm trying to amplitude modulate a .mp3 file which is already saved in the system. Now when I'm trying to multiply it with a high frequency carrier wave I'm getting an error regarding the frames. The audio signal is in a matrix of [1024*1] but the carrier is in a matrix of [1*1] Also I need to convert it into digital form and transmit it using Arduino

I'm using MATLAB 2013 and designing it on Simulink.

Any suggestions?

[Krishna Gaire]

Hi Aman, I am also trying to amplitude modulate a .mp3 file and would really appreciate if you could help me out. I have sound clips that are about 3-4 seconds in human audible range. I want to convert them into ultrasonic range so that when I transmit them they are not audible to humans. I read that I need to use amplitude modulation. I used the modulate function of matlab.

[y,Fs] = audioread('TakeASelfie.mp3');
x = modulate(y,30700, 62000, 'am');
soundsc(x,62000)
audiowrite('modulated.wav', x, 62000)

In the above example, I was trying to convert my audio clip to 30.7kHz. However, after I performed modulation, the length of the clip was decreased. How can I change the frequency of my sound clip without changing the length of it? Thank you.

I have asked the same question in the community as well. If you would like you could answer the question there.

Answer 1

[Walter Roberson]

wavread() already converts the file to digital form.

There is no problem multiplying a 1024 x 1 vector by a 1 x 1 scalar.