oh! That means 341 ppb frequency error, which *really* shouldn't be happening.
I'd like to get some statistics of that error, how are you measuring it? Best regards, Marcus On Wed, 2018-12-05 at 12:55 +0100, Florian Kaltenberger wrote: > Sorry typo. I did use a frequency of 3.51GHz. > > > On 5 Dec 2018, at 12:54, Marcus Müller <marcus.muel...@ettus.com> > > wrote: > > > > Hi Florian, > > > > trying to get my head to understand the order of problems here: > > Could you try to use a higher frequency (say, --freq 2e9 instead of > > 3.5e6)? > > I'd thing 3.51 MHz is out of range for the N310, anyway? > > > > Best regards, > > Marcus > > > > On Wed, 2018-12-05 at 11:49 +0100, Florian Kaltenberger via USRP- > > users > > wrote: > > > So I can confirm that there is a frequency offset between the two > > > USRP N310s when using only an octoclock (10MHz + PPS) to > > > synchronize. > > > I have measured with the tx_waveforms program > > > ./tx_waveforms --args > > > "addr=192.168.x.2,time_src=external,clock_src=external,master_clo > > > ck_r > > > ate=122.88e6" --rate 122.88e6 --freq 3.51e6 --wave-type SINE -- > > > wave- > > > freq 10e6 --gain 100 > > > on the first USRP N310 (x=10) and then on the other (x=20). There > > > is > > > an offset of 1200Hz between the peaks of the sinusoids between > > > the > > > two measurements. > > > Using an external LO didn't change anything either. Unless I need > > > to > > > provide any other arguments in that case? > > > I also tried to do a test where I use both USRPs simultaneously > > > ./tx_waveforms --args > > > "addr0=192.168.10.2,addr1=192.168.20.2,time_src=external,clock_sr > > > c=ex > > > ternal,master_clock_rate=122.88e6" --rate 122.88e6 --freq 3.51e6 > > > -- > > > wave-type SINE --wave-freq 10e6 --gain 100--channels "0,4" > > > but unfortunately that does not work at all at my testbench > > > (program > > > hangs and no signal transmitted). > > > My UHD version is 3.13.0.2 (UHD_3.13.0.HEAD-0-g0ddc19e5) > > > Any help appreciated. > > > Thanks! > > > Florian. > > > > > > > On 04/12/2018 21:29, Florian Kaltenberger via USRP-users wrote: > > > > Hi Marcus and Robin, > > > > thanks for your answers, this is helpful information. I should > > > > add, > > > > that I actually tried the synchronization with an octoclock > > > > (10MHz > > > > + PPS), but it did not give me the expected results, i.e., I > > > > saw > > > > some residual frequency offsets. But maybe I screwed up at some > > > > point. Let me do some more measurements and get back to you on > > > > this. > > > > Florian. > > > > > > > > > On 04/12/2018 18:57, Marcus D. Leech via USRP-users wrote: > > > > > On 12/04/2018 10:14 AM, Florian Kaltenberger via USRP-users > > > > > wrote: > > > > > > Hi there, > > > > > > I just discovered that in addition to the external 10MHz > > > > > > reference in, the USRP N310 also has external local > > > > > > oscilator > > > > > > inputs, one for each daughterboard and each TX/RX. So does > > > > > > that > > > > > > mean that in order to synchronize multiple N310 in > > > > > > frequency, > > > > > > phase, and time, it is no longer sufficient to use an > > > > > > octoclock > > > > > > to provide a 10MHz reference and PPS? If so, at what > > > > > > frequency > > > > > > do you have to drive the external LOs and at what power? > > > > > > Florian. > > > > > > > > > > > In addition to what Robin posted, I'll observe that the > > > > > external > > > > > LO port is an *additional feature* of this device. > > > > > > > > > > You should still be able to use the external 10MHz and 1PPS > > > > > ports > > > > > the same way you would with a B210 or E310, since the AD9371 > > > > > front-end chip is similar to the AD9361 chip used in the > > > > > B210 > > > > > and E310. > > > > > > > > > > The thing about synchronizing multiple independent PLL > > > > > synthesizers, though, compared to a strictly-shared-LO, is > > > > > that > > > > > the former will > > > > > experience both phase ambiguities, and have a higher mutual > > > > > phase-noise than the latter, which is why you might decide to > > > > > choose > > > > > the latter. > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > USRP-users mailing list > > > > > USRP-users@lists.ettus.com > > > > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > > > > > -- > > > > Follow us on Google+, LinkedIn, or Twitter! > > > > > > > > > > > > _______________________________________________ > > > > USRP-users mailing list > > > > USRP-users@lists.ettus.com > > > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > > > -- > > > Follow us on Google+, LinkedIn, or Twitter! > > > _______________________________________________ > > > USRP-users mailing list > > > USRP-users@lists.ettus.com > > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
