Re: [Discuss-gnuradio] Handling of IQ files

[Marcus D. Leech]

On 03/19/2016 02:05 PM, Henry Barton wrote:

So there’s no “read x samples, divide by y, do such-and-such, and you have a frequency-domain array” that I can average over time?

Sent from Windows Mail

Gnu Radio has various types of FFT blocks, filters, decimators, etc, etc.    But there is no big, blue 'Do that thing that Henry Barton wants to do'
  button.  It's a development framework for developing DSP applications, largely in the radio space.  One could *use* Gnu Radio to
  *build* a "signal analysis workbench", but Gnu Radio isn't in and of itself, "a signal analysis workbench".

Just as GCC isn't "that cool spreadsheet app I'd love to have", but it can certainly be *used* to *build* "that cool spreadsheet app I'd love
  to have".

From: Nikos Balkanas
Sent: ‎Saturday‎, ‎March‎ ‎19‎, ‎2016 ‎1‎:‎31‎ ‎PM
To: James Humphries
Cc: Henry Barton, address@hidden

Hi,

I missed your second part. gr-fosphor is realtime, so It will follow whatever frequencies you have. Frequency hops show as frequency bands in a frequency spectrum.

The frequency spread of a single plot, is your sampling frequency.

HTH,

Nikos​

On Sat, Mar 19, 2016 at 7:22 PM, James Humphries <address@hidden> wrote:

Hi Henry,

There is a script, read_complex_binary.m, that is included with gnuradio. You can use that with Octave or Matlab to read the I/Q recordings from a file as a time vector.

-Trip

On Sat, Mar 19, 2016 at 12:43 PM, Henry Barton <address@hidden> wrote:

Is there any simple formula for plotting spectrum (finding the intensity of each frequency component, Hertz by Hertz) from IQ recordings? Specifically I need to know how to read an IQ file and somehow dissect clusters of samples. I’ve written programs that deal with large amounts of data from files, so I think this shouldn't be too hard. I want to write my program so that it takes in a multi-hour IQ file and averages it like the 24-hour band averaging on the University of Twente WebSDR site. This would allow users to average an IQ file over time and see the most active frequencies and times. There’s no utility for this yet, and I’d like to write it and release it on my blog.

On a side note: is it possible to go “frame-by-frame” in an IQ file? For example, to follow the hops of a 900-MHz FHSS device.

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