Re: [Discuss-gnuradio] Fwd: Creating a FFT plot like the one in this youtube variable

[Marcus Müller]

The FFT of any signal you take always represent that signal's whole bandwidth -- so if you have a complex signal taken at 1MS/s, you'll see 1MHz of bandwidth, and if you take one of 100MS/s, you'll see 100MHz.
Hence, this is not by any means a limitation of the processing (FFT) you do to the signal -- it's simply a matter of what your signal represents physically. This question really illustrates the importance of reading up on theory!

Best regards,
Marcus

On 23.07.2015 15:48, Ashraf Younis wrote:

Thank you all so much. I am able to get the single peak with the sin wave. I go through the readings when time allows, thank you for the suggestions.

In the mean time, I am curious to know if GRC is able to produce a FFT for a wide band. For example, can it produce one for the FM radio channels, show its various peaks.

On Thu, Jul 23, 2015 at 9:32 AM, Mike Harpe <address@hidden> wrote:

Seconded.

I am a reader of this list. I am working to learn DSP using Gnuradio and I can tell you firsthand that you have got to do the reading. DSP is very complex math. If you don't have that background it's very slow going. I have had to re-learn trigonometry and basic calculus just to read the introductory material. It's starting to make sense after investing months of hobby time in it.

This list is an invaluable resource as well.

Mike Harpe, N4PLE

Sellersburg, IN

On Thu, Jul 23, 2015 at 9:27 AM, Marcus Müller <address@hidden> wrote:

Hi Ashraf,

A single complex sine tone will only have one spectral peak.
I think you will see great profit in understanding a bit of the math/signal theory involved. GNU Radio has a suggested reading page, especially made for these cases:
https://gnuradio.org/redmine/projects/gnuradio/wiki/SuggestedReading
Go through Michael Ossman's tutorial (under Math).

In fact, reading through that list, there's a distinct lack of free ressources that bridge the gap between "why? and what are complex signals?" and digital communication basics, ie. stuff like "what is the spectrum/a fourier transform".
If you have access to a university library or so, grab a book on basics of signals and linear systems; like in every mature scientific community, there's some healthy dispute on what students should be having access to, but if you're looking for something relative precise, yet not too mathematical and free, have a look at Lapidoth, which is available here as a PDF:
http://www.afidc.ethz.ch/A_Foundation_in_Digital_Communication/Getting_The_Book.html
Read chapters 2 and 6.

Best regards,
Marcus

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