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Digital FM demodulation

Started by benpeterson May 6, 2008
Hi all, 

I have a question,

I have a wav.file, which is a FM modulated signal. It has 3 channels.
I want to demodulate them, in Signal Processing Toolbox of Matlab. (but
just the first and second channel (not the third one))

I used "demod" function, but it functions very bad and the problem is
that, i need to demodulate both channels at the same time (mixed), in order
to have both of them together at the end too.

I don't know how to do it.
As is said, "demod" function returns an unclear plot. 

Do you have any idea, how i can demodulate both channels at the same time?

 

thanx in advance,
benpeterson 


On Tue, 06 May 2008 07:31:39 -0500, benpeterson wrote:

> Hi all, > > I have a question, > > I have a wav.file, which is a FM modulated signal. It has 3 channels. I > want to demodulate them, in Signal Processing Toolbox of Matlab. (but > just the first and second channel (not the third one)) > > I used "demod" function, but it functions very bad and the problem is > that, i need to demodulate both channels at the same time (mixed), in > order to have both of them together at the end too. > > I don't know how to do it. > As is said, "demod" function returns an unclear plot. > > Do you have any idea, how i can demodulate both channels at the same > time? > > > > thanx in advance, > benpeterson
How are the three channels modulated? Is it like FM broadcast radio, with several channels that are frequency division multiplexed at baseband, then FM modulated onto a carrier? Is it three FM carriers each with it's own modulation? What? I'm sure that Matlab's 'demod' function is designed to work with one FM signal, so presumably you'd be able to demodulate the FM broadcast case and do post-processing. If you've got three carriers in your .wav file then you'll have to separate them out and then demodulate. -- Tim Wescott Control systems and communications consulting http://www.wescottdesign.com Need to learn how to apply control theory in your embedded system? "Applied Control Theory for Embedded Systems" by Tim Wescott Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html