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Topic: Quadrature Amplitude Modulation in Real-Time
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GIRAY

Posts: 11
Registered: 1/16/10
Quadrature Amplitude Modulation in Real-Time
Posted: May 30, 2010 3:49 PM
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Hi to all,

I am working on a project for my communications class and I was wondering if any of you can help me out.

I'm using two computers for this project, one is receiver other is transmitter.

The goal is to send two message signals into the sound card, ie two ipods playing simultaneously and use analoginput function in order to take the sound in to MATLAB. The data acquired from two ipods is a matrix of size 44100 x 2. So one column has info for left ipod and other column for the other ipod.

The transmitter and receiver are set up with the use of modulate and demod functions and set up to be a 'qam' modulator and demodulator.

The problem I am encountering is when I recover the signals at the receiver side the signals are mixed, I mean they cannot be seperated. When I set the receiver pc to output from left speaker only, I can hear both of the songs play. I am trying to split the songs so that the QAM scheme is established.

At the receiver side I am setting as follows
chan2=analogout(1,1:2)
so that I can have two columns of info flowing through; the workspace is showing recovered signals as two single column vectors but when I play it they are not splitting to right and left.

Maybe I'm messing up the conversion of Hz to discrete time domain?

If needed I can post my code, thank you.



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