Re: [Discuss-gnuradio] Running OFDM files

[Tom Rondeau]

Jose Emilio Gervilla Rega wrote:
> Hello all,
>
> I will give you more details about my problem because someone has 
> asked me for them(thank you):
>
> The OFDM system we are using is which is defined in this link:
>
> http://gnuradio.org/trac/browser/gnuradio/branches/developers/n4hy/ofdm/gnuradio-core/src/python/gnuradio/blksimpl?rev=5763
>
> The file ofdm.py is the transmitter and the other ones are receiver 
> and synchronization modules. When I run ofdm.py which I've copied into 
> the folder I told you on the other topic(the first one), appear some 
> errors. If I type ./ofdm.py the output is:
>
> ./ofdm.py: line 23: import: order not found
> from: can't read /var/mail/numpy
> from: can't read /var/mail/gnuradio
> ./ofdm.py: line 26: import: order not found
> from: can't read /var/mail/gnuradio.blksimpl.ofdm_receiver
> ./ofdm.py: line 35: sintax error near token no hoped `('
> ./ofdm.py: line 35: `class ofdm_mod(gr.hier_block):'
>
>
> I'm using Linux Ubuntu 7.04 and gnuradio 3.1.1.
>
> Thank you all for help us!!

Jose,

You are not quite using those blocks correctly, anyway. They depend on 
their location to be properly imported. All of the core OFDM blocks are 
locaked in blks2impl and can be imported using gnuradio.blks2:

from gnuradio import gr, blks2

Then you can access blks2.ofdm or blks2.ofdm_receiver.

If you are working on a new type of synchronization, you'll want to 
place that in blks2impl. You'll find there are already four different 
types already there: ofdm_sync_pn, ofdm_sync_pnac, ofdm_sync_ml, and 
ofdm_sync_fixed. The fixed version simply knows how long to delay the 
triggering and assumes no frequency offset and was used just to test the 
mod/demod blocks. Of the rest, only the PN sequence synchronization 
currently works (and may be the only one that will ever work of these).

I think a bit of reorganization is due for the sync blocks, anyway. They 
do 1 or 2 steps too many. I would like to remove the ofdm_sampler from 
it, put that block in ofdm_receiver and output two streams from each 
sync: a timing trigger for when the preamble is detected and the fine 
frequency derotated OFDM symbol. The idea being a general interface for 
different OFDM sync blocks like yours that we could fit in.

Make sense?

Tom