ok. Yes, I always use timed tune commands. If that were not happening correctly, I don't think I could get consistent results with TwinRx.
I am presently using 3.14.1.1. I will complete the testing (using internal LO) I've already begun with this version and then re-test some/all using 3.15. Assuming that the results are different, it would seem that Ettus should consider applying the fixes to the 3.14 branch. Rob On Mon, Jan 27, 2020 at 2:18 PM Nate Temple <nate.tem...@ettus.com> wrote: > Hi Rob, > > One other thing, if you're not on UHD v3.15.0.0, I'd recommend to update > to it. There was some phase reset and accumulator fixes with 3.15.0.0. > > https://github.com/EttusResearch/uhd/blob/UHD-3.15.LTS/CHANGELOG#L44 > > > Regards, > Nate Temple > > On Mon, Jan 27, 2020 at 11:17 AM Nate Temple <nate.tem...@ettus.com> > wrote: > >> Hi Rob, >> >> You should always use a tune request with a timed command when you want >> to align channels. >> >> One thing you could test is to try using the internal LO and see if you >> get different results. >> >> Also you could try using the integer N tuning mode, but I don't think it >> will make any difference for this issue. Checkout this great blog post on >> USRP tuning if you haven't seen it before that covers a few more tips on >> USRP tuning: >> http://www.radio-science.net/2017/12/adventures-in-usrp-tuning.html >> >> Regards, >> Nate Temple >> >> On Mon, Jan 27, 2020 at 9:33 AM Rob Kossler <rkoss...@nd.edu> wrote: >> >>> Hi Nate, >>> I changed the subject as to not further hijack the other thread. Of the >>> 16 captures I collected, some of them included a tuning command (but using >>> the same timed commands I use for other devices such as TwinRx). But, >>> others did not. For example, for the first two data points below (with >>> measured phase difference of -77 and -19 respectively). I simply issued >>> two consecutive timed streaming commands. So, I was very perplexed by the >>> results. >>> >>> In any event, I plan to re-take the data today both with and without a >>> DDC. Hopefully, if I get rid of the DDC, I will see consistent phase >>> results, but we'll see. Let me know if you have other ideas. >>> Rob >>> >>> On Mon, Jan 27, 2020 at 12:04 PM Nate Temple <nate.tem...@ettus.com> >>> wrote: >>> >>>> >>>> @Rob: With the current init process of the N310, yes it is required to >>>> first set the external LO to 5 GHz. >>>> >>>> With regards to the offsets you're seeing, I believe you should only >>>> see a possible phase difference of 180* within the two channels on the same >>>> DB. Are you issuing a tune request at the start of streaming? >>>> >>>> Regards, >>>> Nate Temple >>>> >>>> On Mon, Jan 27, 2020 at 8:20 AM Rob Kossler via USRP-users < >>>> usrp-users@lists.ettus.com> wrote: >>>> >>>>> Robert, Sammy, >>>>> I am presently running some tests which compare the X310/TwinRx and >>>>> the N310 with regard to channel-to-channel phase. In my setup, I have a >>>>> signal source that is split 8 ways (1:8 splitter) to feed the 4 channels >>>>> of >>>>> my TwinRx and 4 channels of my N310. I have seen some strange behavior of >>>>> the N310 that perhaps Robert has experienced? Take a look: >>>>> >>>>> - For the TwinRx (for which I am a more experienced user with LO >>>>> sharing), I get consistent channel-to-channel phase difference among >>>>> all >>>>> channels. This is true regardless of power cycles, re-starts of UHD, >>>>> etc. >>>>> - For the N310 (for which I am a beginner when it comes to >>>>> external LO operation) >>>>> - it seems more complex to run in this mode (as compared to >>>>> TwinRx). In order to get it to work, I have had to disable startup >>>>> QEC >>>>> calibration because it seems that the N310 initial cal occurs at >>>>> 2500 MHz >>>>> RF such that I would need to have my external LO at 5000 MHz for >>>>> startup >>>>> (during the UHD deveice 'make') and then later switch my external >>>>> LO to the >>>>> desired RF*2. Is this true? >>>>> - when I run with either external LO or internal LO, I see >>>>> inconsistent channel-to-channel phase results even between the two >>>>> channels >>>>> of a given daughterboard that share the same LO. I do not >>>>> understand how >>>>> this is possible. My results over 16 captures (with some re-starts >>>>> of UHD, >>>>> device reboots, and switching between internal/external LO) show the >>>>> following channel-to-channel phase difference between channels 0 >>>>> and 1 >>>>> which share the same LO: (values in degrees) -77, -19, -77, -19, >>>>> -77, -19, >>>>> -19, 39, -19, -19, -77, -19, -77, 39, -19, -19. Note that there >>>>> are only 3 >>>>> unique values and the delta happens to be 58 deg, but I don't know >>>>> what >>>>> that implies... >>>>> >>>>> Rob >>>>> >>>>> >>>>>
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