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From: Rehan Dar on 26 Jun 2010 02:57
Hey there

I have been looking around the Communications Reference Guide. I am trying to plot a PAM signal after doing the PAM modulation. I can't seem to be able to find anything that can help me.

Here is how I am generating my PAM signal:

M = 2;
randSeq = randint(1, 256, [1, 0]);
h = modem.pammod;
h.M = M;
h.inputtype = 'integer';
h.symbolorder = 'binary';
pamOutput = modulate(h,randSeq);

I'm new to MATLAB Comm. Tool Kit so forgive me for the stupid questions. What I'm trying to do here is that I have generated a 'binary' sequence of 256 integers. After that's done, I'm trying to modulate this sequence into a Binary PAM signal. After wards, I want to use a RC pulse shaping filter before transmitting it to my channel. Does my code make any sense in regards to what I'm doing?

Also, the main thing I wanted to ask was whether I can view how the Binary PAM signal looks like? Any help is appreciated! Thanks in advance!

-Rehan
From: Wayne King on 26 Jun 2010 06:52
"Rehan Dar" <mrehandar(a)gmail.com> wrote in message <i048c1$cjp$1(a)fred.mathworks.com>...
> Hey there
>
> I have been looking around the Communications Reference Guide. I am trying to plot a PAM signal after doing the PAM modulation. I can't seem to be able to find anything that can help me.
>
> Here is how I am generating my PAM signal:
>
> M = 2;
> randSeq = randint(1, 256, [1, 0]);
> h = modem.pammod;
> h.M = M;
> h.inputtype = 'integer';
> h.symbolorder = 'binary';
> pamOutput = modulate(h,randSeq);
>
> I'm new to MATLAB Comm. Tool Kit so forgive me for the stupid questions. What I'm trying to do here is that I have generated a 'binary' sequence of 256 integers. After that's done, I'm trying to modulate this sequence into a Binary PAM signal. After wards, I want to use a RC pulse shaping filter before transmitting it to my channel. Does my code make any sense in regards to what I'm doing?
>
> Also, the main thing I wanted to ask was whether I can view how the Binary PAM signal looks like? Any help is appreciated! Thanks in advance!
>
> -Rehan

Hi Rehan, the modulate method outputs a complex-valued baseband representation of your signal.

stem(real(pamOutput))

Does that answer your question?

Wayne
From: Rehan Dar on 26 Jun 2010 16:09
"Wayne King" <wmkingty(a)gmail.com> wrote in message <i04m4l$k1q$1(a)fred.mathworks.com>...
> "Rehan Dar" <mrehandar(a)gmail.com> wrote in message <i048c1$cjp$1(a)fred.mathworks.com>...
> > Hey there
> >
> > I have been looking around the Communications Reference Guide. I am trying to plot a PAM signal after doing the PAM modulation. I can't seem to be able to find anything that can help me.
> >
> > Here is how I am generating my PAM signal:
> >
> > M = 2;
> > randSeq = randint(1, 256, [1, 0]);
> > h = modem.pammod;
> > h.M = M;
> > h.inputtype = 'integer';
> > h.symbolorder = 'binary';
> > pamOutput = modulate(h,randSeq);
> >
> > I'm new to MATLAB Comm. Tool Kit so forgive me for the stupid questions. What I'm trying to do here is that I have generated a 'binary' sequence of 256 integers. After that's done, I'm trying to modulate this sequence into a Binary PAM signal. After wards, I want to use a RC pulse shaping filter before transmitting it to my channel. Does my code make any sense in regards to what I'm doing?
> >
> > Also, the main thing I wanted to ask was whether I can view how the Binary PAM signal looks like? Any help is appreciated! Thanks in advance!
> >
> > -Rehan
>
> Hi Rehan, the modulate method outputs a complex-valued baseband representation of your signal.
>
> stem(real(pamOutput))
>
> Does that answer your question?
>
> Wayne

Thanks alot Wayne! It helped....i see that the PAM modulation maps the 0's to -1 and 1's to +1's...my question is what part does the complex part of the PAM output plays in this whole case (If you dont mind answering)? How can we just ignore it?
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