[time-nuts] Serial or other simple protocols for exchanging time
I would use the NMEA ZDA message. An (easily fixed) issue with Tom's suggestion is the message does not start with a unique character... that can cause issues with syncing to the message (syncing to the end of the previous message has its own issues). Ideally a time message should start/end with unique characters and always be the same length long. Lady Heather does not use a 1PPS input, but has code to read the time encoded in whatever message it uses to drive the display and display time. That code adjusts the message time for any offset between the time in the message and the actual time the message arrives (Heather uses the time-of-arrival of the last byte in the time message). The time offset correction is receiver dependent (it can also be affected by the operating system and serial port/USB interface).Heather uses a default, receiver dependent, time offset or the use can specify the offset (they can be positive or negative) and also has a command for measuring it (provided the OS clock is accurate). ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Precision Time Protocol – Windows 10 implementation
On Thu, Aug 8, 2019 at 7:00 PM David J Taylor via time-nuts < time-nuts@lists.febo.com> wrote: > Hi everybody! My first post here, I hope the subject is adequate for this > mailing list. > > I'm using a tiny layer 1 NTP server consisting of Raspberry Pi 3B+ with > Ublox MAX-M8Q expansion board providing GNSS (currently GPS, Galileo and > Glonass, sometimes I switch to Beidou, too) reference with PPS + a simple > patch antenna hanging near the window. Offset, jitter and rms are most > often smaller than 1 µs. The server is included in NTP pool. > > I'm using several Windows 10 machines on the same LAN, all using NTP client > software from Meinberg. The typical offset and jitter in those are about > 100-500 µs. I would like to make it lower. > [] > Thanks in advance for any suggestions! > > Adam Kumiszcza > > > Adam, > > You could feed the PPS signal to the Windows PCs as one way of making the > performance better: > > https://www.satsignal.eu/ntp/setup.html > > Performance: > > https://www.satsignal.eu/mrtg/performance_ntp.php#windows-stratum-1 > > Cheers, > David > First of all, thank you for the info you put on satsignal.eu org! I've used some of these in the initial configuration of my server. By feeding PPS signal to the Windows PC you mean adding cards or connecting boards (like Sure Electronics GPS evaluation boards) to Windows computers? My idea was to lower the time offset of machines connected by LAN to a single stratum-1 server. But maybe I'll come to that later. Out of your monitored servers on https://www.satsignal.eu/mrtg/performance_ntp.php I am amazed by performance of LeoNTP box. What do you mean by indoor antenna here? Best regards, Adam ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Precision Time Protocol – Windows 10 implementation
On Thu, Aug 8, 2019 at 7:01 PM Tim Lister wrote: > On Thu, Aug 8, 2019 at 8:07 AM Adam Kumiszcza > wrote: > > > > Hi everybody! My first post here, I hope the subject is adequate for this > > mailing list. > > > > I'm using a tiny layer 1 NTP server consisting of Raspberry Pi 3B+ with > > Ublox MAX-M8Q expansion board providing GNSS (currently GPS, Galileo and > > Glonass, sometimes I switch to Beidou, too) reference with PPS + a simple > > patch antenna hanging near the window. Offset, jitter and rms are most > > often smaller than 1 µs. The server is included in NTP pool. > > > > I'm using several Windows 10 machines on the same LAN, all using NTP > client > > software from Meinberg. The typical offset and jitter in those are about > > 100-500 µs. I would like to make it lower. I've heard that one of the > > latest versions of Windows 10 provides support for PTP protocol (IEEE > > 1588v2). Hence my questions: > > > > 1. Did anybody try using it on Windows 10 already? From what I can tell > > right now, there's only a demonstration web site showing it works when > > using Ubuntu Linux as a virtual machine [1]. Or should I wait a bit for > > more robust implementation? > > EndRun Technologies > (https://endruntechnologies.com/products/grandmaster-clocks/ptp-slaves) > make mention of a Windows PTP slave - not sure if it's the same > version you have found. It does also make mention of the fact that > precision is limited on Windows depending on version although from > what I gather from the satsignal.eu that precious on Windows improved > with 7 or later. > It's additional software here. As far as I understand, recent Windows 10 versions introduced under-the-hood internal implementation of PTPv2, with kernel support for it. > > 2. Do I guess correctly that current implementation of PTP works only on > > Ethernet? Some of the computers are on wlan. > > For deterministic timing I think it has to be Ethernet and as outlined > in their white paper (https://endruntechnologies.com/pdf/PTP-1588.pdf) > it works best if you have hardware timestamping in the NICs at each > end and IEEE1588 compatible network switches (and even when the claim > to support it, apparently they don't always do it properly: > > https://www.linkedin.com/pulse/ptp-support-high-end-ethernet-switches-heiko-gerstung > ). > You may be able to do some Pi-to-Windows PTP experiments with a > crossover cable. Not sure if the Pi has the hardware timestamping, > seems unlikely given the low cost of the Pi's as in the 3B+ (and below > I believe) the Ethernet is provided by a combined Ethernet/USB2 hub > and limited by the speed of the USB2. > Pi 3B+ has only software timestamping, and even this is not completely clear (I had to patch the kernel). Pi-to-Windows direct crossover testing is a great idea! Best regards, Adam ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Precision Time Protocol – Windows 10 implementation
On Thu, Aug 8, 2019 at 4:07 PM Adam Kumiszcza wrote: > Hi everybody! My first post here, I hope the subject is adequate for this > mailing list. > > I'm using a tiny layer 1 NTP server consisting of Raspberry Pi 3B+ with > Ublox MAX-M8Q expansion board providing GNSS (currently GPS, Galileo and > Glonass, sometimes I switch to Beidou, too) reference with PPS + a simple > patch antenna hanging near the window. Offset, jitter and rms are most > often smaller than 1 µs. The server is included in NTP pool. > > I'm using several Windows 10 machines on the same LAN, all using NTP client > software from Meinberg. The typical offset and jitter in those are about > 100-500 µs. I would like to make it lower. I've heard that one of the > latest versions of Windows 10 provides support for PTP protocol (IEEE > 1588v2). Hence my questions: > > 1. Did anybody try using it on Windows 10 already? From what I can tell > right now, there's only a demonstration web site showing it works when > using Ubuntu Linux as a virtual machine [1]. Or should I wait a bit for > more robust implementation? > 2. Do I guess correctly that current implementation of PTP works only on > Ethernet? Some of the computers are on wlan. > 3. Is there any other way of making the clients' time offset lower? > Although there is one method using WSL, there is also the "native" method https://techcommunity.microsoft.com/t5/Networking-Blog/Top-10-Networking-Features-in-Windows-Server-2019-10-Accurate/ba-p/339739 "Precision Time Protocol - Try it out!" PTP can be used across any IP network, but if there is non deterministic latency (jitter), there is a fairly obvious effect. The offset should reduce over time, but jitter will affect this. I've already tried setting PTP on the Raspberry Pi 3B+. It needed a kernel > recompilation with a patch I found here: [2], but I'm not sure it works > correctly. > I have run PTP on a rPi 3B without any kernel modifications as a grandmaster (with a ublox GPS to provide time and PPS), and experimented with different NICs (intel, broadcom and solarflare, all with HW timestamping) as clients in x64 hosts. There are two issues with using a rPi as a PTP grandmaster, the crystal is "not very stable", and the NIC is connected over USB, both of these add jitter which is noticeable on PTP. The jjitter is obvious when compared to a meinberg m600 with the HQ OXCO option.connected to a Solarflare NIC in a Linux host. To remove the jitter issues, you might care to try the ublox connected (via a suitable level converter for NMEA and PPS) to a hardware serial port on a Linux X64 host. I have not tried the native Windows PTP client, there are also 3rd party clients from greyware and fsmlabs. > As you can see on the screenshot below, PTP appears here as a server, but > I'm not sure if it's used at all. > [image: status16.PNG] > > Ptp4l status shows this: > > pi@zegar:~ $ systemctl status ptp4l > ● ptp4l.service - Precision Time Protocol (PTP) service >Loaded: loaded (/lib/systemd/system/ptp4l.service; enabled; vendor > preset: enabled) >Active: active (running) since Wed 2019-08-07 12:32:28 CEST; 24h ago > Docs: man:ptp4l > Main PID: 323 (ptp4l) > Tasks: 1 (limit: 4915) >CGroup: /system.slice/ptp4l.service >└─323 /usr/sbin/ptp4l -f /etc/linuxptp/ptp4l.conf -i eth0 > > Aug 07 12:32:31 zegar ptp4l[323]: ptp4l[6.631]: port 1: link up > Aug 07 12:32:31 zegar ptp4l[323]: ptp4l[6.631]: port 1: FAULTY to LISTENING > on FAULT_CLEARED > Aug 07 12:32:31 zegar ptp4l[323]: [6.631] port 1: link up > Aug 07 12:32:31 zegar ptp4l[323]: [6.631] port 1: FAULTY to LISTENING on > FAULT_CLEARED > Aug 07 12:32:38 zegar ptp4l[323]: ptp4l[13.526]: port 1: LISTENING to > MASTER on ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES > Aug 07 12:32:38 zegar ptp4l[323]: ptp4l[13.526]: selected best master clock > b827eb.fffe.006e65 > Aug 07 12:32:38 zegar ptp4l[323]: ptp4l[13.526]: assuming the grand master > role > Aug 07 12:32:38 zegar ptp4l[323]: [13.526] port 1: LISTENING to MASTER on > ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES > Aug 07 12:32:38 zegar ptp4l[323]: [13.526] selected best master clock > b827eb.fffe.006e65 > Aug 07 12:32:38 zegar ptp4l[323]: [13.526] assuming the grand master role > > Thanks in advance for any suggestions! > > Adam Kumiszcza > > [1] > > https://techcommunity.microsoft.com/t5/Networking-Blog/Windows-Subsystem-for-Linux-for-testing-Windows-10-PTP-Client/ba-p/389181 > [2] https://github.com/twteamware/raspberrypi-ptp/issues/2 > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Precision Time Protocol – Windows 10 implementation
From: Adam Kumiszcza First of all, thank you for the info you put on satsignal.eu org! I've used some of these in the initial configuration of my server. By feeding PPS signal to the Windows PC you mean adding cards or connecting boards (like Sure Electronics GPS evaluation boards) to Windows computers? My idea was to lower the time offset of machines connected by LAN to a single stratum-1 server. But maybe I'll come to that later. Out of your monitored servers on https://www.satsignal.eu/mrtg/performance_ntp.php I am amazed by performance of LeoNTP box. What do you mean by indoor antenna here? Best regards, Adam ___ Adam, One thing - I note you say "single stratum-1 server". With GPS/Raspberry Pi being so cheap, why not have several servers each with a separate antenna? You already have a PPS signal from your existing GPS, so I was thinking simply of distributing that the the Windows PCs, and feeding it to the serial port's DCD signal. If the PC doesn't have a serial port, check on the motherboard because there are sometimes serial port headers left unconnected by the PC manufacturer. If it doesn't have such a header, add a serial port card. If it's a laptop then you might use a serial-over USB connection, but that's likely either not to carry the serial control lines, or be of inferior performance to other methods. LeoNTP - my shack is on the second floor of a UK 2-storey house, and the antenna for the LeoNTP is a magnetic-mount standard puck antenna, mounted on the base of an desk light which is actually on top of a loudspeaker, so the antenna is near the roof but indoors. Check with your Android mobile phone what the GPS signal levels actually are in your possible locations - I think Apple don't allow you to access that information. For this level of performance there's no need for timing antennas. My other GPS antennas are simple on a window sill on a south-facing, second floor window. http://www.satsignal.eu/ntp/2019-01-08-1330-23b-GPS-antenna-farm.jpg The key here is to have some conducting magnetic material under the antenna, not just sitting on its own. There's more about the LeoNTP here: http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=272 Cheers, David -- SatSignal Software - Quality software for you Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] TI LMK05318 clock sync
Anyone had a play with this device ? 1pps (or whatever) input, http://www.ti.com/lit/ds/symlink/lmk05318.pdf For those with a radio interest, or telecom interest.. I will order an eval board and see what its like... Yeah, I know its easy to do with a micro or fpga , but the phase noise from the internal VCO is impressive. I have no idea what the random stuff < 1Hz in adev territory is like. -glen ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
