RE: [Discuss-gnuradio] OFDM results.

[Per Zetterberg]

> -----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 ?