On Wed, Sep 1, 2010 at 9:15 PM, Sam Keene <[email protected]> wrote:

> Ok, thanks, One more question... So does that mean we control the NCO from
> the software?
>
> I will have a look at those blocks.
>
> thanks,
>
> -Sam



No, the NCO is free running. We compensate for it in software.

Tom




> --- On *Wed, 9/1/10, Tom Rondeau <[email protected]>* wrote:
>
>
> From: Tom Rondeau <[email protected]>
> Subject: Re: [Discuss-gnuradio] Newbie question on USRP2, synchronization
> done by the FPGA?,
> To: "Sam Keene" <[email protected]>
> Cc: [email protected]
> Date: Wednesday, September 1, 2010, 9:03 PM
>
>
> On Wed, Sep 1, 2010 at 8:52 PM, Sam Keene 
> <[email protected]<http://mc/[email protected]>
> > wrote:
>
> Hi,
>
> Thanks for the reply. I guess I am just trying to better understand this
> diagram:
>
>
> http://www.linuxjournal.com/files/linuxjournal.com/linuxjournal/articles/073/7319/7319f3.inline.jpg
>
> I understand what the decimating filters are doing, but I'm a little
> unclear about the NCO. Does this component phase and frequency lock for me,
> or will I have to code that myself?
>
> thanks,
>
> -Sam
>
>
> No, there is no freq/phase lock in the USRP/USRP2. We have to do this in
> software.
>
> You can reference the dbpsk and dqpsk blocks that we have already written
> or the newer dbpsk2/dqpsk2 blocks that use newer techniques for the phase,
> frequency, and timing locks.
>
> Tom
>
>
>
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