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Thread Subject:
How to observe QAM singals in time-domain in Simulink?

Subject: How to observe QAM singals in time-domain in Simulink?

From: Lei

Date: 19 Apr, 2010 07:45:09

Message: 1 of 3

I am trying to build up an OFMD transmitter by using Simulink. The chosen modulation scheme is 64-QAM. I am wondering how to observe the QAM signals in time-domain.

My simulink model consists of the following key blocks: Random integer generator, QAM modulator, S/P converter, IFFT block, Cyclic prefix block, buffer and Spectrum scope.

After the IFFT algorithm, the frequency-domain QAM signals in converted to time-domian signals. How to observe the QAM signals in time-domain?

Many thanks if someone can give some guidance./Lei

Subject: How to observe QAM singals in time-domain in Simulink?

From: koubaa kamal

Date: 26 Apr, 2010 10:48:05

Message: 2 of 3

Hello,
I think there is nothing to observe after IFFT, but you can observe the QAM signal after the QAM bloc, using the "XY graph" bloc that you find in simulink/Sinks, but before that you need to get the real and imaginary parts of the QAM signal, you'll find the bloc for that in math operations in Simulink bloc set, you may need to use Scope also to visualize the imaginary and real signals independently.

> After the IFFT algorithm, the frequency-domain QAM signals in converted to time-domian signals. How to observe the QAM signals in time-domain?

Subject: How to observe QAM singals in time-domain in Simulink?

From: Warren Nunez

Date: 26 Apr, 2013 03:41:09

Message: 3 of 3

"koubaa kamal" <kamal.koubaa@gmail.com> wrote in message <hr3r15$fs2$1@fred.mathworks.com>...
> Hello,
> I think there is nothing to observe after IFFT, but you can observe the QAM signal after the QAM bloc, using the "XY graph" bloc that you find in simulink/Sinks, but before that you need to get the real and imaginary parts of the QAM signal, you'll find the bloc for that in math operations in Simulink bloc set, you may need to use Scope also to visualize the imaginary and real signals independently.
>
> > After the IFFT algorithm, the frequency-domain QAM signals in converted to time-domian signals. How to observe the QAM signals in time-domain?

Sir, I want to observe the time domain representation of the QAM signal. How do I do it? Referring to the constellation diagram, I want to have something like A*sin(wt + phi). Where 'A' is the amplitude of the constellation and 'phi' is the phase shift.

My initial plan is to separate the complex signal from the QAM modulator into its AMPLITUDE and PHASE by using the complex to amplitude-angle bloc. Then substitute the values to the equation A*sin(wt + phi). My problem now is on how to implement A*sin(wt + phi) in simulink. Or is there another way to do it?

Thanks in advance for anyone who can help me with this matter.

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