The "timed command" concept in UHD allows multiple N2xx with SBX or WBX to be phase-aligned on tuning, using a special "resynch"
hardware feature of the synthesizers used (ADF4351). However, this functionality is not exposed in the gr-uhd interface. Furthermore, on the WBX, even with timed commands there will be a 180deg phase-ambiguity, due to the 2XLO mixer. The units will either be in-phase with each other, or exactly 180deg out-of-phase with each other, since the state of the divider in the 2XLO mixer cannot be controlled from the outside. On 2014-09-15 09:36, Ralph A. Schmid, dk5ras wrote: > As far as I know this phase error is caused by the PLL concept that does not > care for the phase of the reference to build the output signal always with > reproducible phase relation to the reference. > > So you will have to find some workaround like an auto align procedure, or use > another transceiver concept that keeps the phase consistent through the whole > path, from the reference to the output carrier. > > Ralph. > > FROM: [email protected] > [mailto:[email protected]] ON BEHALF OF > sarankumar > SENT: Monday, September 15, 2014 7:27 AM > TO: GNURadio Discussion List > SUBJECT: [Discuss-gnuradio] phase synchronizing USRPs in GNU Radio > > Hi all, > > I am trying to phase synchronize multiple usrp's using 10 MHz reference and 1 > pps. I was able to get them synchronised but with constant phase offset > between. But every time I retune or rerun the flowgraph the phase offset > changes. how can I estimate and compensate the phase offset between USRPs > without rerunning or retuning USRP? The purpose is to do DOA estimation. I > use WBX daughterboard and USRP N210. > > Regards, > > Saran > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio [1] Links: ------ [1] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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