Hi Moses, The PPS input is just a trigger that is used to set the time on the device. There is nothing for it to lock to and currently nothing that detects the presence of the signal. Setting the clock and time source on the USRP Sink/Source blocks to external and the Sync to "unknown PPS" will sync the device time to the PPS signal. More directly, you can use the set_time_next_pps() and set_time_unknown_pps() methods to set the time on the device to a specific time.
Regards, Michael E. West On Fri, May 17, 2024 at 7:21 AM Moses Browne Mwakyanjala <mbkit...@gmail.com> wrote: > Hi Marcus, > > The external 10MHz did the trick. I have another related question which I > think we can address here without opening a new ticket. The USRP B210 has a > 1PPS port. However, I was not able to poll the status of the time source, > "pps_locked". When I searched for a list of all onboard sensors, the only > visible sensor was "ref_locked". Am I missing something? How can I use and > poll the status of 1PPS? > > Regards, Moses > > > On Wed, May 15, 2024 at 6:04 PM <discuss-gnuradio-requ...@gnu.org> wrote: > >> Send Discuss-gnuradio mailing list submissions to >> discuss-gnuradio@gnu.org >> >> To subscribe or unsubscribe via the World Wide Web, visit >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> or, via email, send a message with subject or body 'help' to >> discuss-gnuradio-requ...@gnu.org >> >> You can reach the person managing the list at >> discuss-gnuradio-ow...@gnu.org >> >> When replying, please edit your Subject line so it is more specific >> than "Re: Contents of Discuss-gnuradio digest..." >> >> >> Today's Topics: >> >> 1. USRP B210 Frequency Offset (Moses Browne Mwakyanjala) >> 2. Re: USRP B210 Frequency Offset (Marcus D. Leech) >> >> >> ---------------------------------------------------------------------- >> >> Message: 1 >> Date: Wed, 15 May 2024 11:52:27 +0200 >> From: Moses Browne Mwakyanjala <mbkit...@gmail.com> >> To: GNURadio Discussion List <discuss-gnuradio@gnu.org> >> Subject: USRP B210 Frequency Offset >> Message-ID: >> < >> cabysgdmphq54warsy--5-7renj3pfrahtowuce_rss8ypq-...@mail.gmail.com> >> Content-Type: text/plain; charset="utf-8" >> >> I've encountered a consistent frequency offset of around 2ppm with my new >> B210. Operating at a sample rate of 4 MSPS with the "internal" clock, all >> calibrations were performed using a sine wave from an Agilent signal >> generator. >> >> Though seemingly minor, the 800Hz offset at UHF poses challenges in >> receiving low-rate data from orbiting satellites. Is there an automated >> method to approximate and mitigate this offset? Currently, I manually >> adjust the frequency by subtracting the offset in ppm. However, I'm >> curious >> if there are more sophisticated solutions available, excluding reliance on >> GPS or a 10MHz reference. >> >> Best regards, >> Moses >> >> [image: image.png] >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: < >> https://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20240515/3082954d/attachment.htm >> > >> -------------- next part -------------- >> A non-text attachment was scrubbed... >> Name: image.png >> Type: image/png >> Size: 33653 bytes >> Desc: not available >> URL: < >> https://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20240515/3082954d/attachment.png >> > >> >> ------------------------------ >> >> Message: 2 >> Date: Wed, 15 May 2024 09:10:13 -0400 >> From: "Marcus D. Leech" <patchvonbr...@gmail.com> >> To: discuss-gnuradio@gnu.org >> Subject: Re: USRP B210 Frequency Offset >> Message-ID: <ec4c50e0-0e19-494a-b25b-f273464fe...@gmail.com> >> Content-Type: text/plain; charset="utf-8"; Format="flowed" >> >> On 15/05/2024 05:52, Moses Browne Mwakyanjala wrote: >> > I've encountered a consistent frequency offset of around 2ppm with my >> > new B210. Operating at a sample rate of 4 MSPS with the "internal" >> > clock, all calibrations were performed using a sine wave from an >> > Agilent signal generator. >> > >> > Though seemingly minor, the 800Hz offset at UHF poses challenges in >> > receiving low-rate data from orbiting satellites. Is there an >> > automated method to approximate and mitigate this offset? Currently, I >> > manually adjust the frequency by subtracting the offset in ppm. >> > However, I'm curious if there are more sophisticated solutions >> > available, excluding reliance on GPS or a 10MHz reference. >> > >> > Best regards, >> > Moses >> The on-board clock on a B210 is good to about 2.5PPM. So, it's working >> as you would expect. >> >> There's nothing built in to the UHD API for this, because normally, if >> you care about clock accuracy beyond what the internal clock >> can supply, you use an external, better, clock. GPSDOs are not very >> expensive these days, and you can pick up used >> 10MHz OCXO units fairly cheaply as well... >> >> >> > >> > image.png >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: < >> https://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20240515/db078ea5/attachment.htm >> > >> -------------- next part -------------- >> A non-text attachment was scrubbed... >> Name: image.png >> Type: image/png >> Size: 33653 bytes >> Desc: not available >> URL: < >> https://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20240515/db078ea5/attachment.png >> > >> >> ------------------------------ >> >> Subject: Digest Footer >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >> ------------------------------ >> >> End of Discuss-gnuradio Digest, Vol 259, Issue 8 >> ************************************************ >> >
