Re: [Discuss-gnuradio] Benchmark_ofdm_tx Benchmark_ofdm_rx

[Eric Blossom]

On Tue, Jul 01, 2008 at 05:17:06PM +0200, matteo zunino wrote:
> 
> > > > > Hi,
> > > > > 
> > > > > i've a question about these two functions. My aim is to modify these
> > > > > benchmarks in order to create a trasmission system that can choose
> > > > > to put on a single carrier a BPSK or a QPSK modulation. My problem
> > > > > is this one, how can i comunicate to the receiver what carriers are
> > > > > BPSk adn what QPSK?
> > > > > 
> > > > > Thanks a lot
> > > > 
> > > > This is typically done by sending some kind of 'map' at the low rate
> > > > at the beginning of packet.  Take a look at WiMAX to see how
> > > > complicated this can get ;)
> > > > 
> > > > Eric
> > 
> > > I've seen it ;) but i've problem too even if i konw what carriers
> > > are BPSK and what are QPSK. I've studied how to modify ofdm.py in
> > > order to transmitt for example the first 10 signals with BPSK
> > > modulation and tre other with QPSK, but when i want to demodulate, i
> > > don't know which point of gr_ofdm_frame_sink.cc i must modify to
> > > demodulate correctly. Do you think my project is possible actually
> > > in gnuradio OFDM?
> > 
> > Sure it's possible.  You'll have to do some work.


> Excuse me for the continue questions but i've not such a big
> experience in Gnuradio. Where i i would modify gr_ofdm_frame_sink.cc
> in order to arrive to my aim? I don't know c++ language very well
> and i don't know where i can find it in this function
>
>  Thanks a lot
>
> Matteo

Matteo, I haven't looked at this code in a while and don't plan to at
this time.  I'm working on other pieces of GNU Radio right now.

You asked me if it's possible, and I said yes.  It will take some
study and some work.  Perhaps this is an opportunity to improve your
programming skills?  You may have to look beyond gr_ofdm_frame_sink.cc
and understand how the whole OFDM system is put together.

Each piece and feature of GNU Radio got written because somebody cared
about that part.  We all started out knowing nothing.  You appear to
be the person that cares about doing different modulations on
different subcarriers.  You know what you want.  You know a little bit
about the current code.  You're exactly where you're supposed to be to
get started on it...

Good luck!
Eric