On 11/01/12 08:31 PM, Armando Rocha wrote: > Hi > > Please note that I am referring to a differential phase. Even if the NCO > phase is not continuous the differential phase should remain unchanged (I > think the NCO is the same). > > Thanks for your contribution > > > Ah, OK. So you're dealing with two independant DDC chains here, which operate off of two different NCOs, as far as I know, since in most cases the two chains may be tuned to entirely different frequencies. I think the NCOs are programmed separately, from UHD, which means there will be a phase difference between them every time the (two) NCOs are programmed.
Fixing this would require FPGA changes in the USRP1, which at this point is utterly frozen as far as I know. You'd need some kind of "commit" logic that caused the two NCOs to be re-started at exactly the same time after being programmed. I don't *think* this can be done purely within UHD, but maybe it can. I'm sure Josh or Matt could comment. This is similar to what happens with the synthesized analog cards--they end up with some random differential phase offset every time their frequencies are changed, due to the way the frac-N synthesizers work. -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
