• To: mathgroup at smc.vnet.net
• Subject: [mg43812] Re: Signal Processing Help please..
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Tue, 7 Oct 2003 02:40:51 -0400 (EDT)
• Organization: Universitaet Leipzig
• References: <blj5ft\$1e2\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

the Fourier[]  transform may be complex, and you should Plot[]
the Abs[] value or the Arg[]ument

Regards
Jens

"Marcos G." wrote:
>
> Hi guys,
> I am a new user of Mathematica 4.0 and I am trying to do some signal
> analyzis when I get some weird errors with Mathematica.
> Please, any help are welcome and I really appreciate it.
> What I want to do is:
>
> I have this PAM signal definition:
>
> s(t) = Sum(ak p(t-kT),k=0,k=15)
>
> {ak} is a binary sequence with k going from 0 to 15
> ak = {0010011010111100}
>
> And p(t) is a pulse:
>
>             +------+
>              |           |
>              |           |
> +-------+          +-------+
> -1.5  -0.5   0   0.5      1.5  ---------------->
>                                                                  t
>
> More details is attached in the notebook file.
> [contact the author to get the attachmenet -moderator]
>
> What I want to do is to get the Fourier Transform of the PAM signal
> s(t).
>
> The problem is that when I plot this fourier transform I am getting
> always:
>
> "is not a machine size real number...."  and the plots comes empty, just
> with the axis.
>
> For me it seems ok, but I can't understand why is complaining.
>
> Thanks you all..
>
> Marcos

```

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