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Re: [Discuss-gnuradio] Newbie question on USRP2, synchronization done by

From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] Newbie question on USRP2, synchronization done by the FPGA?,
Date: Wed, 1 Sep 2010 21:28:52 -0400

That's no different than a straight analog receiver though, where LO phase is generally not coherent with carrier or modulation phase. So you use PLL or similar demodulators to recover carrier phase


Principal Investigator
Shirleys Bay Radio
Astronomy Consortium

On Sep 1, 2010, at 9:19 PM, Tom Rondeau <address@hidden> wrote:

On Wed, Sep 1, 2010 at 9:15 PM, Sam Keene <address@hidden> 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.



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


--- On Wed, 9/1/10, Tom Rondeau <address@hidden> wrote:

From: Tom Rondeau <address@hidden>
Subject: Re: [Discuss-gnuradio] Newbie question on USRP2, synchronization done by the FPGA?,
To: "Sam Keene" <address@hidden>
Cc: address@hidden
Date: Wednesday, September 1, 2010, 9:03 PM

On Wed, Sep 1, 2010 at 8:52 PM, Sam Keene <address@hidden> wrote:

Thanks for the reply. I guess I am just trying to better understand this diagram:


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?



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.


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