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Re: [Discuss-gnuradio] OFDM results.

From: Bob McGwier
Subject: Re: [Discuss-gnuradio] OFDM results.
Date: Fri, 06 Jun 2008 14:37:48 -0400
User-agent: Thunderbird (Windows/20080421)

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.


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.



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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