Re: [Discuss-gnuradio] Synchronize USRP in which level

[Josh Blum]

On 01/30/2013 09:00 PM, Gong Zhang wrote:
> Hi,
> My last topic "Synchronize multiple USRP-N210s"may be a big one which
> gives no reply.If I want to synchronize two USRPs without cable or
> GPSDO,I should design a synchronization protocol.Simply A sends some
> time-stamped samples to B ,then B record local time when receiving these
> samples.Knowing the distance between them,we can synchronize B with
> A.Apparently the synchronization accuracy depend on we make the
> timestamps in which level.Ethernet involve in 10s of microseconds jitter
> shows that we should do it on FPGA.Does UHD have this function?
> Any comments will be valuable to me.
> Thanks.

Start here, you can do this with plain UHD in C++ or with the gnuradio
gr-uhd component in python or C++:
http://code.ettus.com/redmine/ettus/projects/uhd/wiki

The sync docs should explain just about everything:
http://files.ettus.com/uhd_docs/manual/html/sync.html

Many examples of timed transmission and reception:
http://code.ettus.com/redmine/ettus/projects/uhd/wiki#Code-Examples

Awesome project/use case for these features:
https://github.com/jmalsbury/pre-cog/wiki

-josh

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