Re: [Discuss-gnuradio] RFX 900 200mW

[Vincenzo]

Thanks Matt!
really precious answer..
actually, transmitting an 8 MHz wide signal at 820MHz without bypassing
the ISM filter.. what kind of attenuation should I expect? ..I mean..
just a rough estimate of its magnitude..

thanks

vincenzo


On Tue, 2008-07-29 at 00:06 -0700, Matt Ettus wrote:
> Vincenzo Pellegrini wrote:
> >
> > Hi everybody,
> > just a simple question:
> > does the RFX900 provide 200mW just out of the box? Do I have to take 
> > care of something in particular in order to obtain them?
> >
> > Actually, what are the appropriate gain values that I should pass to 
> > subdev.set_gain() n order to maximize correctly the output power?
> >
> > Sorry for bthering the list with such questions but I was unable to 
> > have them answered in the RFX900 section of the wiki.. maybe I'll add 
> > them myself once I'll have fully understood the issue..
> 
> 
> That is a saturated power level.  For any linear signal you will need to 
> back off a bit.  In any case, you control the output power by 
> controlling the amplitude of the signal you send to the USRP.  +/-32767 
> will be the max power but will result in RF clipping.  You will need to 
> find the max power you can get with your particular signal and still 
> maintain enough linearity.  If you need a dB or 2 more, you can bypass 
> the ISM band filter with a cap of about 100pF and then cut the traces to 
> the filter.
> 
> Matt
>