Re: [Discuss-gnuradio] Modifying vectors

[Patrick Strasser]

Eric Blossom wrote:
> On Fri, Mar 17, 2006 at 10:27:45AM +0100, Patrick Strasser wrote:
>
> > Hello!
> >        fft = gr.fft_vfc(fft_size, True, window.hanning(fft_size))
> >        ifft = gr.fft_vcc(fft_size, False, window.hanning(fft_size))
> >
> >        self.connect(s2p, fft      )
> >        self.connect(fft, ifft     )
> >        self.connect(ifft, p2s     )
>>
> > now I want to modify data between fft and ifft.
> > Do I have to make a custom block in python (I'd like to do this anyway...)?
>
> Depends on what you want to do.  A few of the blocks support an
> optional "vlen" constructor argument.  These will apply the given
> operation to a vector of items.
>
> If for example you want to independently filter the bins, you could
> use gr.stream_to_streams, a bunch of filter blocks, then
> gr.streams_to_stream.  See
> gnuradio-core/src/python/gnuradio/blksimpl/filterbank.py 

So you can use these blocks with vectors of that type too. Clever shortcut!

No, I want to interpolate between the bins. I want to modify the 
spextrum. I know there is at least one other way (resampling), but this 
is the most straight forward way for me.

> This isn't completely sorted out.  Besides adding the "vlen" attribute
> to many blocks, we've also considered using a Numeric  / NumPy / SciPy
> "ufunc" (universal function) mechanism and then a small number of
> GNU Radio blocks that know how to apply ufuncs across streams.
> "ufuncs" would probably be easier to write in the common cases than
> full GNU Radio blocks.

And a ufunc would be able to modify the stream on the fly?

Patrick
--
Engineers motto: cheap, good, fast: choose any two
Patrick Strasser <patrick dot strasser at  tugraz dot at>
Student of Telematik, Techn. University Graz, Austria