I just realized my last message was rejected because of the size of the attachments. I am resending it with the picture in Google Drive.
Indeed, just for completeness: The captures below were done with the case open, one with the GPSTXCO connected and without it: With it: https://drive.google.com/file/d/173OqgJsi_7j0BYpE939FipxcMe8onXuI/view?usp=drivesdk Without it: https://drive.google.com/file/d/16vPzIC1fLphIlyw-_QG5Yc4pm0fgBC0H/view?usp=drivesdk The difference is quite noticeable. And if on top of it, you close the case, you have the perfect storm. Thanks Fran On Fri, Jan 5, 2024, 11:53 Francisco Gallardo lópez < f.gallardo.lo...@gmail.com> wrote: > Indeed, just for completeness: > > The captures below were done with the case open, one with the > GPSTXCO connected and without it: > > With it: > > > Without it: > > > > The difference is quite noticeable. And if on top of it, you close the > case, you have the perfect storm. > > Thanks > Fran > > El jue, 4 ene 2024 a las 18:36, Francisco Gallardo lópez (< > f.gallardo.lo...@gmail.com>) escribió: > >> >> I was guessing that because grabbing the device out of the box makes the >> interference weaker, I would say that even taking the GPS TCXO out also >> helps, a bit. >> >> Did somebody try soldering some metallic shielding on the board? it seems >> like it is designed for that. >> >> >> On Thu, Jan 4, 2024, 18:16 Marcus D. Leech <patchvonbr...@gmail.com> >> wrote: >> >>> On 04/01/2024 10:54, Francisco Gallardo lópez wrote: >>> >>> Hi Brian, >>> >>> Yes sir, precisely each 80 MHz... You found the root cause. >>> >>> Shit, that is a considerable inconvenience. I saw the spike gets >>> stronger or weaker depending on whether the USRP box is opened. Actually, >>> it is weaker when opened. I will check whether I can improvise some >>> shielding directly in the board itself. >>> >>> Any suggestions here? >>> >>> This STRONGLY suggests that the mechanism is radiative coupling. The >>> box acts as a waveguide cavity at certain frequency >>> ranges. Lining the box with carbon-foam RF absorber will help. >>> >>> This also explains why my observations show the spur as considerably >>> weaker--I'm using an ad-hoc box from Hammond that >>> is quite a bit larger than the factory box. >>> >>> >>> >>> Thanks! >>> Fran >>> >>> >>> On Thu, Jan 4, 2024, 16:00 Brian Padalino <bpadal...@gmail.com> wrote: >>> >>>> On Thu, Jan 4, 2024 at 8:52 AM Francisco Gallardo lópez < >>>> f.gallardo.lo...@gmail.com> wrote: >>>> >>>>> As for the USB2, I just tried. It is still there (see attached (you >>>>> can see the USB type in the terminal)) >>>>> >>>>> [image: Screenshot from 2024-01-04 13-31-53.png] >>>>> >>>> >>>> 1560 MHz is the 39th harmonic of the 40 MHz reference used in the >>>> device. >>>> >>>> Check to see if you have interference spikes every 80 MHz or so. >>>> >>>> Brian >>>> >>> >>> _______________________________________________ >>> USRP-users mailing list -- usrp-users@lists.ettus.com >>> To unsubscribe send an email to usrp-users-le...@lists.ettus.com >>> >>> >>> _______________________________________________ >>> USRP-users mailing list -- usrp-users@lists.ettus.com >>> To unsubscribe send an email to usrp-users-le...@lists.ettus.com >>> >>
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