Re: [Discuss-gnuradio] USRP and XCVR2450 Noise Figure

[bjoernm]

Zitat von "Matt Ettus" <address@hidden>:

> On 07/15/2010 08:51 AM, Jeffrey Lambert wrote:
> > Hello,
> >
> > The noise figure will in large part depend upon the receiver front-end
> > that is attached the USRP or in the daughter board that is used. In that
> > case that you would like to know the noise figure of the USRP without
> > any RF front-end then the results may vary whether you are using a
> > BasicRX board or one of the LFRX boards. For a 50 Ohm system, either of
> > these should yield accurate results. Mainly, the noise figure of the
> > USRP will be derived from the AD9862 digitizer. Since this IC contains
> > an amplifier, the noise figure will vary with the gain of the PGA.
> >
> > I too am interested in measuring the noise figure of the USRP. If you
> > are unable to find anything, I will be able to supply measurement data
> > within the next few weeks for a USRP device and BasicRX daughterboard.
>
> The USRP + BasicRX will have a noise figure of around 35dB, since it  
> has no amplification.  If designing a daughterboard, you can use  
> that number as the noise figure of the ADC for your calculations of  
> the overall noise figure.
>
> Matt


Hi,

Thanks a lot for your help!

Can I also use those 35db as the total noise at the input of the USRP  
to compute the signal to noise ratio?

For that I'd also need the transmitting Power Pt. Would you by any  
chance also have an idea how i could figure out Pt?

best and thanks a lot!
Björn