Re: [Discuss-gnuradio] OFDM results.

[Bob McGwier]

The USRP is not in the same league with the USRP2.  The on board 
oscillator is much better but external oscillators will make it even 
better.  So the answer is a big yes, the USRP2 will be better.

Bob


Per Zetterberg wrote:
>  
>
>   
> > -----Original Message-----
> > From: Bob McGwier [mailto:address@hidden 
> > Sent: den 6 juni 2008 09:23
> > To: Per Zetterberg
> > Cc: address@hidden; 'Per Zetterberg'
> > Subject: Re: [Discuss-gnuradio] OFDM results.
> >
> > In your sixteen QAM and other figures I see two effects.
> >
> > Notice just the slightest hint that arcs through the top four 
> > constellation points in the 16 QAM is not straight.  This 
> > curvature is caused by nonlinearity.
> >
> > Your result almost surely can NOT be clock jitter.  If you 
> > had a lot of clock jitter,  the pictures would look much 
> > worse.  Notice the dispersion gets larger as your proceed 
> > away from the origin.  This is almost surely phase noise in 
> > some oscillator.
> >
> > Bob
> >
> >     
>
> Thanks!
>
> New question:
> Would the phase noise get smaller in USRP2 where we can use an external
> reference, given that we use a high precision external reference ?
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