Re: [Discuss-gnuradio] Re: new to GNU radio

[George Nychis]

Brian Padalino wrote:
> On Tue, Mar 4, 2008 at 1:27 PM, Manav Rohil <address@hidden> wrote:
> > thanks for the replies...
> >  So that means if i dont have a USRP, i cannot simulate a packet
> >  transmission/reception entirely in software since the data will never be
> >  modulated to the carrier frequency.
>
> No need for a USRP ... just simulation!
>
> >  What is the alternative..Write a mixer block(using gr.multiply_cc) in
> >  software and feed the data bits and a local oscillator to this?The
> >  output of the mixer will then be the modulated signal at the carrier
> >  frequency i want...And then I demodulate it using costas's receiver...
>
> It depends on what you're trying to simulate.  The RF hardware with
> I/Q phase/DC imbalances?  Just baseband distortions?  Fading?  Doppler
> spread?  Multipath?  AWGN?
>
> I recommend the book:
>
>     "Simulation of Communication Systems" ISBN 0-306-46267-2
>
> It's heavy on the math, and it's really for advanced readers - but it
> covers everything.
>
> I believe there may be some channels implemented within GNU Radio
> right now, but there hasn't been much discussion of using GNU Radio
> strictly for simulation.
>
> Hope this helps.

There is a basic channel model added in the benchmark_loop.py case:
http://gnuradio.org/trac/browser/gnuradio/trunk/gnuradio-examples/python/digital/benchmark_loopback.py#L35

- George