Re: [Discuss-gnuradio] Understanding the c++ interface

[Eric Blossom]

On Tue, Nov 14, 2006 at 06:37:05PM -0800, Dan Halperin wrote:
> Eric Blossom wrote:
> > The rx_mux value of -1 means "do the right thing".  It ends up setting
> > the mux to 0x32103210.
> >
> > The tx_mux value of -1 means "do the right thing".  For the single
> > channel case it sets it to 0x0098.
> >   
> 
> Cool. Thanks!

You're welcome!

> > The basic_tx has _very_ low output power.
> > Be sure to set the rx gain to its maximum value.
> >   
> 
> This seems to have fixed the problem.

Good.

> Interesting. Does this mean that the python scripts are doing
> daughterboard-specific cleverness to get good output even though they
> report the gain to be 10db? (I intend to dive into the Python scripts in
> the future to see what's up, I just haven't had time yet).

Actually the RX side of the RFX daughterboards contains an additional
h/w gain control.  We control all the gains with a single knob, since the
daughterboard specific python code (db_*.py) knows how they should
work together.

>From the python interface we export a couple of useful
methods:

  u.subdev.gain_range()  -> (min, max, step_size)   # in dB (more or less)
  u.subdev.set_gain(g)

The gain_range returned is a function of the daughterboard to which
you are talking.

> >> As an aside, is there a good reason the decimation/interpolation
> >> arguments are not standardized across the various scripts? It's hard to
> >> remember whether the argument is -I, -i, -D, or -d... similar questions
> >> apply to frequency arguments (-f vs. -F).
> >
> > The arguments are standardized across the python code.  Please feel
> > free to submit a patch that makes these match the python code.  (You
> > happen to be using two pieces of C++ code that were written at the
> > beginning of time to test early usrp functionality.  They don't get
> > used much, and were almost dropped from the distribution because they
> > don't know how to talk to the daugtherboards.)
> >   
> 
> Well then I'll have to do just that :-).

Thanks!

Eric