Re: [Discuss-gnuradio] Handling of IQ files

[Nate Temple]

Hi Henry,

Here are a few open source applications you may find useful to reference to 
build your tool.

rtl_power + heatmap.py (c/python) - Hard coded to use the RTL-SDRs
https://github.com/keenerd/rtl-sdr/blob/master/src/rtl_power.c
http://kmkeen.com/rtl-power/

rtl_power port that uses FFTW - https://github.com/AD-Vega/rtl-power-fftw

inspectrum (c++) - https://github.com/miek/inspectrum

Such Samples by Tim O'Shea - GR Based Sample Data File Visualization
https://oshearesearch.com/2015/05/22/such-samples-a-gnu-radio-tool-for-sample-data-visualization/
https://oshearesearch.com/2015/12/08/such-samples-2/

- Nate


> On Mar 19, 2016, at 11:05 AM, Henry Barton <address@hidden> 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
> 
> 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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