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.
on 2013-01-31 04:02
on 2013-01-31 04:52
On 01/30/2013 09:00 PM, Gong Zhang wrote: > 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/w... Awesome project/use case for these features: https://github.com/jmalsbury/pre-cog/wiki -josh
on 2013-01-31 07:55
2013/1/31 11:51, Josh Blum wrote: On 01/30/2013 09:00 PM, Gong Zhang wrote: >> Thanks. > Awesome project/use case for these features: > https://github.com/jmalsbury/pre-cog/wiki > > -josh My target is to sample signal at the same time with two USRP connected to different PCs placed in different place.The sync accuracy should be within microsecond.I can not use cable and GPSDO,which gives no external sync signal such as PPS.The only way maybe sync their local time,which is usually unsynchronized due to the instability of oscillator.So I need a time-stamp exchange based sync protocol. Thank you for your time.
on 2013-01-31 09:28
On 01/31/2013 12:54 AM, Gong Zhang wrote: >>> Any comments will be valuable to me. >> > Thank you for your time. Sounds feasible. Suppose you did something simple like a synchronization pulse. Send out a pulse that all devices could detect. Record the time the pulse was detected at each device to establish an absolute time amongst the devices. The precog project does stuff like this for the frequency hopping and TDMA engines to sync up the time windows for transmission and hopping, etc... https://github.com/jmalsbury/pre-cog/wiki -josh