Re: [Discuss-gnuradio] Handling of IQ files

[Henry Barton]

I'm planning to write my program from scratch in C#. I understand the basics of the FFT now; I had always wondered how transient signals would show up in a window if they were significantly shorter than the time covered by an FFT window, and I see now that there is a tradeoff: more samples = higher frequency precision but fewer FFT windows can be drawn. I've observed this in HDSDR where RBW can be either frequency-precise or do fast windowing. But as everyone says, the FFT is tremendously complex, so I will probably use a 3rd-party library. I'm currently working out how to use the AForge .NET library.

> Date: Tue, 22 Mar 2016 09:20:41 +0100
> From: vittben@gmail.com
> To: discuss-gnuradio@gnu.org
> Subject: Re: [Discuss-gnuradio] Handling of IQ files
>
> Happy to read you replay Henry!
> Feel free to rip/change/upgrade my work, but let me know about ur progress, pse!
> Remember that it's fairly resource hungry ( file larger that 250 Mb
> crashes the app also on my I7/16Gb), but it's a starting point.
> I think that with GNURADIO it's possible to refine this task... I've a
> lot to study!
>
> Victor I3VFJ
>
> 2016-03-21 20:45 GMT+01:00 Henry Barton <kw4eg@outlook.com>:
> > I like the concept of your program. It looks just like what I’m trying to
> > write.
> >
> > Sent from Windows Mail
> >
> > From: Vitt Benv
> > Sent: ‎Sunday‎, ‎March‎ ‎20‎, ‎2016 ‎4‎:‎16‎ ‎PM
> > To: discuss-gnuradio@gnu.org
> >
> > Hi,
> > this [ https://sourceforge.net/projects/automodrecog/ ] is my little
> > effort about handling IQ files.
> > The input IQ file is recorded with HDSDR, very nice piece of sw, that
> > as a good recording scheduler. By the way the file provided can be
> > played with it. I do also some tests with IQ file produced by R&S
> > EM100 receiver.
> > I wrote this [horrible] application for personal use and it's very raw
> > IMO....
> > I'm interested on HF monitoring and the main goal is to find SSB
> > emission along time, not quite simple task.
> >
> > In brief:
> > - read params from input file
> > - split it in smaller chunk and save FFT for each chunk
> > - sum (maxhold) or avg (average) all the FFTs
> > - find relevant ( over threshold) carrier and try to "pack" them to
> > find "bandwidth" associated
> > - build a report as .html page with a .png file that represent the result.
> >
> > The most difficult part is to estimate the best "threshold", and at
> > the moment I'm almost stuck there.... and moreover RL reclaims my
> > presence :-)
> >
> > ... my euro "cent" on the subject.
> >
> > Victor I3VFJ
> >
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