Thank you very much for your reply. Really appreciate your efforts. Thats very bad news for me :/
Would it be possible to obtain the same effect with an external RF mixer? I have two LFTX v1.0, however i am transmitting a complex message signal? Maybe i could use the LF boards to modulate an external carrier at 900 MHz, and then still use my current code. Marcus D. Leech wrote: > > > > You can't reliably get a fixed, known phase-offset because the > synthesizers on most cards are fractional-N synthesizers, and they have > a random phase offset every time they're retuned or reset. > > This is > standard behavior for frac-N synthesizers, and not peculiar to USRP > hardware. > > The only exception is the the SBX card, which has > experimental code to use a special SYNC feature to allow initial phase > offsets to be the same across multiple SBX. This requires both new UHD > drivers, and new FPGA code to make it work. > > On Tue, 17 Apr 2012 > 05:42:51 -0700 (PDT), RuneS wrote: > >> Hello on the list, >> >> Im using > Gnuradio 3.3.0, for other reasons, thus is the only option for me >> for > this project. However Im currently trying to make a 180 phase > difference >> from Tx_A to Tx_B, of the same signal on a USRP1. >> >> > Hence i make my signal source, like : >> >> src = gr.sig_source_c(100000, > gr.GR_CONST_WAVE, 1, 0) >> >> my sink: tx = usrp.sink_c(0, nchan=2, > fusb_block_size = 1024, >> fusb_nblocks=4, fpga_filename=fpga) >> >> make > interleaver: intl = gr.interleave(gr.sizeof_gr_complex) >> >> make a > complex 180' phase turner for my Tx_B branch: multip_B = >> > gr.multiply_const_cc((-1 - 0j)) >> >> connect like so: >> >> > self.connect(src, (intl, 0)) >> self.connect(src, multip_B, (intl,1)) >> > self.connect(intl, tx) >> >> I get signal on both Tx outputs, however i > have a 4 db signal level >> difference, and every time i run my program i > get a different phase >> difference, between my two outputs? Im using a > network analyser, to check >> the difference. It looks pretty random? >> > >> Lastly my daughterboards are from 3-10-2006. From earlier maling > list >> replies i understand that they are already made to run on FPGA > clock, which >> fits with a steady phase difference, however is random > for everytime i run >> my program. I dont see 180' as i expect + the > phase keeps changing, for >> every run. There is no noticeable driff when > the program is running. >> >> Hope im clear, or else please reply > question, and i'll clarify as i can. > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > -- View this message in context: http://old.nabble.com/Gnu-Radio-3.3.0-signal-phase-shift-tp33701392p33703596.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
