Re: [Discuss-gnuradio] EDACS Control Channel

[Eric Blossom]

On Sat, Apr 15, 2006 at 10:43:40PM -0500, Rick Parrish wrote:
> Ryan Pape wrote:
> 
> >Given my rudimentary knowledge on the topic (and gnuradio in general)
> >which (if any) of the examples present would be my best starting point
> >given that I'm hoping to do this, even initially, right off the air
> >with the TV RX?
> > 
> >
> To follow-up on Ryan's original question ... I've looked at the examples 
> and documentation. A few grumbles ...
> 

> 1. I can't find straightforward examples.

Start here:
  http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html


The non-GUI examples are considerable more simple than the GUI
examples.   Try usrp_wfm_rcv_nogui.py (Yes, it's wideband, not
narrowband, but it's pretty simple).

For narrow band rx, try usrp_nbfm_rcv.py

> 2. there are no comments (no, the GPL preamble doesn't count)

Several of the examples contain comments, as does the majority of the
guts of the implementation.  We generally don't comment stuff that's
obvious.  We do assume a working knowledge of python.

> Part of the problem (for me at least) is that I don't write Python. It's 
> just not my choice for scripting.


Nice tutorial here: http://docs.python.org/tut/tut.html
Or if you prefer PDF, try this: http://docs.python.org/download.html


> Let me see if I can translate what Ryan wants into the types of building 
> blocks found in GNU radio.
> 
> 1. something to convert the USRP into a NBFM receiver. I've seen an NBFM 
> example but again, it's all python so I can't tell where to modify it 
> for this application. I'd like to break this out into two peices.

Extract receive_path from usrp_nbfm_rcv.py

> 1a. "how-to" example that downconverts an RF signal into an IF or 
> baseband signal

Take a look at gnuradio-examples/python/usrp/usrp_rx_cfile.py.  
It tunes the front end and DDC, decimates and writes the resulting
complex baseband data to a file.

> 1b. "how-to" example that builds on the above to produce AM, FM, or NBFM 
> audio from the baseband or IF samples; this includes various bandwidths 
> ie. 100 khz, 30khz, 15khz and 8 khz.

http://www.nd.edu/~dshen/GNU/Tutorial/7.html
http://www.nd.edu/~dshen/GNU/


> Some other nice-to-have how-tos are:
> 
> 1. read data from an audio file (with the audio chunks delivered in 
> "real" time) and/or record to an audio file.

In gnuradio-examples/python/audio:

   audio_play.py
   audio_to_file.py
   audio_copy.py

> 2. a sample processing block that adds some sort of audio effect along 
> with example plumbing that uses the audio.in and audio.out (PC 
> microphone and speakers).

  spectrum_inversion.py


Eric