Re: [Discuss-gnuradio] help accessing fft bins in python script

[mleech]

The vector sink is for debugging only.  Don't use it in production code, because there's no convenient way to

  vacuum it out, so it grows without bound.

 

When I've had this problem, I use a vector-probe block, and have a function probe running at a couple of Hz,

  and then leverage the dependency-tree evaluator to have my own function called with the result of the

  function probe.  There are other ways, that's the one I personally find most convenient. But there are message

  queues and sundry other methods as well.

 

 

 

 

On 2014-10-16 13:36, Brad Hein wrote:

 

Using qa_fft.py for inspiration[1], I'm trying to feed a raw capture file into an fft of size 32 and then review the 32 fft bins at an instantaneous point in time[2]. I must be doing something wrong however because when I review the vector sink's data() method, it returns a rather large array (compared to the 32-element array I am expecting). data() seems to return an array with the same number of elements as samples fed into the fft. I just want an array of the 32 fft bins so I can calculate the relative power in the given band.

 

Any help/pointers appreciated! 

Thanks

 

 

[1] http://gnuradio.org/redmine/projects/gnuradio/repository/revisions/master/entry/gr-fft/python/fft/qa_fft.py

[2] https://github.com/regulatre/grfun/blob/9dbbf676d2fea013787720273af0b419699c75a4/hello-fft/decodeDump162.py

 

 

[Brad Hein]

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