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

[Martin Braun]

A very simple way would just be to write your block downstream of the
FFT in Python. You can then operate on the vectors in the work function.

M

On 10/16/2014 07:44 PM, address@hidden wrote:
> 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]
>>
>> _______________________________________________
>> Discuss-gnuradio mailing list
>> address@hidden <mailto:address@hidden>
>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
> 
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