Re: [questions] GPS+PPS vs NTP server, why a huge offset ?
On 24/06/2022 11:26, Harlan Stenn wrote: I chatted with him a couple of months' ago. He's doing OK. Thanks, that's good to hear. He did a lot of work, which was much appreciated. Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv -- This is questions@lists.ntp.org Subscribe: questions+subscr...@lists.ntp.org Unsubscribe: questions+unsubscr...@lists.ntp.org
Re: [questions] GPS+PPS vs NTP server, why a huge offset ?
On 23/06/2022 15:33, Thibaut HUMBERT wrote: Hi David! I tested with your dll: https://www.satsignal.eu/ntp/x86/loopback-ppsapi-provider.zip The PPS was not detected, I don't know what I did wrong. Here is the content of my ntp.conf: server 127.127.20.3 minpoll 2 maxpoll 2 mode 89 prefer fudge 127.127.20.3 time2 0.125 refid NMEA server 127.127.22.1 minpoll 2 maxpoll 2 true fudge 127.127.22.1 refid uPPS FYI, the pagehttps://kb.meinbergglobal.com/kb/time_sync/ntp/ntp_for_windows/using_pps_signals_on_windows was updated today, there is a new link to "serialpps-20120321-signed.zip". Thibaut, It's not "my" DLL, but one provided by Meinberg IIRC. If you use the PPS you /must/ mark one of your other sources as "prefer". Without that any PPS doesn't work. I take it that my Serial Port LEDs program shows a flashing DCD (when NTPd is stopped)? Good to hear that there is an updated link. -- Cheers, David Web: https://www.satsignal.eu -- This is questions@lists.ntp.org Subscribe: questions+subscr...@lists.ntp.org Unsubscribe: questions+unsubscr...@lists.ntp.org
Re: [questions] GPS+PPS vs NTP server, why a huge offset ?
On 22/06/2022 22:42, Thibaut HUMBERT wrote: I continued my tests with the NMEA+PPS on a CH341A in USB, and comparing over one night with several NTP sources: I am at ± 1ms on average. I tried with an ESP8266: without success. I tried a Raspberry PI 1B: ok, but always an 10ms offset. And the solution is difficult to transport in the middle of nowhere for a night with the telescope. Now, I use an another desktop computer (with RS232) with the CH341A for the NMEA on USB and the pin PPS directly connected on the RS232 CD. The PPS signal is well detected by the softwarehttps://www.satsignal.eu/software/net.htm#SerialPortLEDs However, I can't find the zip for using the PPS DLL on the real serial interface: http://people.ntp.org/burnicki/windows/serialpps-20120321-signed.zip The link is down, and nothing on Google Do you know where I can find the zip serialpps-20120321-signed.zip? Thanks everyone! Thibaut, The original serial driver hack doesn't work on Windows-10, IIRC. Instead use the PPS API Loopback Provider. https://kb.meinbergglobal.com/kb/time_sync/ntp/ntp_for_windows/using_pps_signals_on_windows As I don't see that for download, I have put my copy on my Web page. https://www.satsignal.eu/ntp/x86/index.html https://www.satsignal.eu/ntp/x86/loopback-ppsapi-provider.zip Please let Martin Burnicki know about the errors on his Web page. -- Cheers, David Web: http://www.satsignal.eu -- This is questions@lists.ntp.org Subscribe: questions+subscr...@lists.ntp.org Unsubscribe: questions+unsubscr...@lists.ntp.org
Re: [questions] Re: GPS+PPS vs NTP server, why a huge offset ?
On 17/06/2022 03:03, Daniel O'Connor wrote: Yes, Thiebaud, USB is not good enough for PPS signals! This is absolutely false. If you are using it for NTP then GPS+PPS over USB is quite adequate (from personal experience). Ian Lepore (RIP) who worked for Micro Semi and worked on FreeBSD did a bunch of tests on a PPS over USB setup and found it more than acceptable for keeping a PC in (good) time. Here's the thread:https://lists.freebsd.org/pipermail/freebsd-arm/2019-August/020263.html See if your motherboard has a true serial port - perhaps just as a header but not a back connector. If not, just set the offset of the PPS to ~10.3 milliseconds (10.3 - IIRC the offsets are in milliseconds but please check). Plus or minus 10.3, try it and see! Not perfect, but better than nothing. You might find better results using that GPS/PPS with a Raspberry Pi as a stratum-1 server and offering that as a server on your LAN. The next level would be something where you can do an input capture on the PPS I don't think there are any pre canned solutions. I made one with a Beagle Bone Black and a uBox GPS module but it's not exactly turn key. Or for a server then you would need a fancy (ie ) internal card. The Raspberry Pi does not have an input capture timer, but I believe you can do better with DMA hackery (I haven't tried though). If a 125 us uncertainty in the PPS is something you can tolerate, so be it. If you are bothering with PPS then presumably you want better accuracy than can be achieved without it. No need for DMA hackery. Standard NTP with the Raspberry Pi can handle PPS on a GPIO signal with a couple of edits to allow the PPS support already built into the kernel to be attached to the appropriate GPIO pin. Not out of the box, but very little effort required. The Raspberry Pi can act as a server for hundreds of clients. If you mean a PC-based Windows server, that's not something I would immediately recommend, but if you must a £20 serial card may be all you need to add. -- Cheers, David Web: http://www.satsignal.eu -- This is questions@lists.ntp.org Subscribe: questions+subscr...@lists.ntp.org Unsubscribe: questions+unsubscr...@lists.ntp.org
[questions] Re: GPS+PPS vs NTP server, why a huge offset ?
On 16/06/2022 10:00, Thiebaud HUMBERT wrote: To do the inversion, I just changed the "Pulse Mode" parameter to "Falling edge" from "Rising edge". The offset induced by the "pulse length" has disappeared. But there is still an offset of around 10.3ms, which I think is induced by USB as explained in this article about other chipsets (https://lists.freebsd.org/pipermail/freebsd-usb/2019- August/016078.html) Yes, Thiebaud, USB is not good enough for PPS signals! See if your motherboard has a true serial port - perhaps just as a header but not a back connector. If not, just set the offset of the PPS to ~10.3 milliseconds (10.3 - IIRC the offsets are in milliseconds but please check). Plus or minus 10.3, try it and see! Not perfect, but better than nothing. You might find better results using that GPS/PPS with a Raspberry Pi as a stratum-1 server and offering that as a server on your LAN. Cheers, David -- Cheers, David Web: http://www.satsignal.eu -- This is questions@lists.ntp.org Subscribe: questions+subscr...@lists.ntp.org Unsubscribe: questions+unsubscr...@lists.ntp.org
Re: [questions] Re: Date and time are wrong.
On 10/06/2022 11:15, David Woolley wrote: On 10/06/2022 08:47, joshua wrote: connect to the right timezone NTP doesn't use timezones. All servers use times based on UTC. Any timezone issue is a local problem, in your operating system. Maybe he means the zone for the pool servers, but there's too little information to help. David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv -- This is questions@lists.ntp.org Subscribe: questions+subscr...@lists.ntp.org Unsubscribe: questions+unsubscr...@lists.ntp.org
[questions] Re: Date and time are wrong.
On 10/06/2022 08:47, joshua wrote: As title states, we've been unable to connect to the right timezone without doing it manually. I was wondering if anybody has been having these problems? I have already tried to change the server to the Dutch server with no succes.. The times are now so far apart that our Yealink products arent able to even communicate anymore. Firewall allowing NTP? Operating system? Source and version of NTP? Post configuration file? -- Cheers, David Web: http://www.satsignal.eu -- This is questions@lists.ntp.org Subscribe: questions+subscr...@lists.ntp.org Unsubscribe: questions+unsubscr...@lists.ntp.org
Re: [ntp:questions] Use of ntpd in Centos8
On 26/06/2021 07:58, Derek Barnes wrote: Thanks David. sudo yum remove chronygets rid of chrony and 62 dependencies but sudo install ntp fails. (Error: Unable to find a match: ntp) I believe /assume that there is no ntp packages in the centos8 repositories. Can my installation be forced to use a different repository such as centos7 ?? I don't know Centos8, but my immediate reaction is: "If it doesn't support NTP, don't touch it". OK, a bit extreme, but NTP works on all my other devices (Linux, Raspberry Pi, Windows, and even some stand-alone devices). One of my issues with Linux is that there are too many incompatible versions! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Use of ntpd in Centos8
On 26/06/2021 05:45, Derek Barnes wrote: I have recently built a server running Centos8 only to find that it doesnot support ntpd, only chronyd. That would not be a problem except that chrony does not like my stratum 1 GPS receiver and the only possible reason that I can work out is the incorrect Precision figure reported. (see below) Is there anyway that I can force ntpd onto Centos8 or anyway I can make chrony ignore this missing number? cheers, Derek. Perhaps? sudo apt-get remove chrony sudo apt-get install ntp -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Best method to measure NTP performance/drift. Loopstats or Peerstats
On 29/01/2021 10:33, Fabbri, Tommaso CMRE wrote: Dear NTP users, which is the difference between loopstats and peerstats for evaluating the drift respect a given timing source? In my configuration, the NTP server is configured with just one additional source (GPS) always available. Should this stats file report the same data? How can I increase the frequency of the log lines in the stats? Is there a way to have one line per second or should I "interrogate" the ntp daemon with ntpq, ntpdc commands? Thank you so much for the support. Tommaso Fabbri Tommas0, I use MRTG for monitoring both Linux and Windows servers: https://www.satsignal.eu/ntp/NTPandMRTG.html It's adequate for my purposes, and you can run it as often as you want. Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Pi 4 and Ultimate hat weirdness
On 25/01/2021 16:33, Jim Pennino wrote: [] But the PPS has a lot of jitter. Note the xPPS(0) in the ntpq line. []> The default for NTP is 4800 baud, but I am running at 9600 and there is no loss of data. It doesn't make any difference if I run the 20 driver in mode 1 (lower bits) or 13, it still has the uncorrectable offset problem. Right now, having been running for a little over 12 hours, ntpq shows: x127.127.20.0.GPS.0 l 14 16 3350.000 -761.21 307.138 *127.127.28.0.SHM.0 l 12 16 3770.000 -30.575 35.029 o127.127.22.0.PPS.0 l3 16 3770.000 -0.378 0.034 I'm going to let it run for several days without disturbing anything. I doubt it will keep the 28 clock selected with that high jitter. If the PPS has a lot of jitter I would try to check it with an oscilloscope. Possibly there is a poor connection, or if you are using a very long cable (unlikely) there could be capacitive coupling between signals. How did you correct the problem for your "over 12 hours" ntpq report? I would suggest a much higher baud rate, and disabling sentences other than $GPRMC. You don't then need any lower bits set. Are you sure that the type 20 and type 28 driver can co-exist? I note that minicom can't access ttyAMA0 when gpsd is using it. From data I'm recording from another GPS I see offsets between -100 and +100 milliseconds from a nominal, with an older Skylab SKG16B device running at 9600 baud. Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Pi 4 and Ultimate hat weirdness
On 25/01/2021 17:53, Gary E. Miller wrote: Yo David! On Mon, 25 Jan 2021 11:03:46 + David Taylor wrote: GPSD has proved problematical, and the only satisfactory way is not to use the one in the distribution, but to build from scratch. https://www.satsignal.eu/raspberry-pi/UpdatingGPSD.html Correction, your distros gpsd packages are problematic, not gpsd. Please file issues with your upstream. It's the PPS which matters, and for that I've found it most satisfactory to use the type 22 driver. Since you are willing to risk the failures that gpsd prevents that ntpd 22 does not. RGDS GARY Yes, Gary, it's that the GPSD in the distributions are almost never the latest version with the fixes. It's a rapidly developing piece of software. Fortunately I've not seen any issues with using the Type 22 driver here. Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Pi 4 and Ultimate hat weirdness
On 25/01/2021 02:06, Jim Pennino wrote: I got a Pi 4 and Adafruit ultimate gps hat to play with and decided to see how good it was as a timekeeper. First weird thing; xgps does not show a skyview but both xgps and cgps show at least 10 satellites in use. I don't care too much about this one as AFAIK xgps is broken on Pi. Second weird thing; I started the 20 driver in mode 0. ntpq showed lots of syntax errors on the $GPGGA message. I changed the mode to 29 to deselect $GPGGA; no errors from ntpq. So maybe it was a satellite thing, but whatever it was, no more errors. Third and biggest weird thing; I had fudge 127.127.20.0 flag1 1 time1 0.001 in ntp.conf. After everything settled down, the clock was showing an offset of -1043. OK, So I changed time1 to 1.044 even though it looked too big. ntp wouldn't lie to me... After everything settled down this time the offset was showing an average of -738. For grins and giggles I set time1 to 0.738 and now the average offset is -584. time1 offset 0.001 -1043 1.044 -738 0.738 -584 It seems there is no way to get time1 to correct the offset. Also the jitter times look high. At this moment ntpq shows: xGPS_NMEA(0) .GPS.0 l6 16 3670.000 -849.36 25.536 *SHM(0) .SHM.0 l4 16 3770.000 -106.55 72.688 xPPS(0) .PPS.0 l4 16 3770.000 18.702 18.812 For comparison, a GlobalSat BU-353-S4 USB GPS on a PC ubuntu system shows: *SHM(0) .SHM.0 l3 16 3770.000 -0.728 1.356 Anyone got any suggestions other than to trash the Ulitmate hat and get another GlobalSat USB? I've been playing with the RPi4 recently and had mostly success. I've used a couple of different devices including the Uputronics/ublox HATs. GPSD has proved problematical, and the only satisfactory way is not to use the one in the distribution, but to build from scratch. https://www.satsignal.eu/raspberry-pi/UpdatingGPSD.html It's the PPS which matters, and for that I've found it most satisfactory to use the type 22 driver. For time of day I tend to use other local or Internet servers. I've been experimenting with an RTC, but experimenting with its unstabilised drift first to understand how well it might behave left for a day, week or month. https://www.satsignal.eu/raspberry-pi/Uputronics-RTC.html Offsets near 1 second introduce an ambiguity and I would suggest avoiding such devices. However, I would expect the AdaFruit to be good - have you set a sufficiently high baud rate? Recent ublox are being set to 115200 to capture all the data. IIRC, $GPRMC alone is enough. Just some random thoughts, not a definitive solution! Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP not seeing servers with a 2-year offset, stand alone configuration
On 19/01/2021 20:04, Martin Burnicki wrote:
Maybe have a look at this page:
http://doc.ntp.org/current-stable/drivers/driver28.html
Search that page for "flag1". There should be 2 hits about a constraint
in the initial time offset ("Mode-independent post-processing"), and how
this can be disabled by setting flag1 to 1.
Maybe this helps.
Regards,
Martin
Thanks for that, Martin. I knew the capability had to be /somewhere/
but I couldn't find it!
However, in this case the RTC was not being driven correctly, and it was
losing its setting under some circumstances - I think the
battery/super-capacitor was being disconnected over power-down! I was
pointed to the notes about correcting the register settings so that this
wasn't done, and backup power was kept. I wrote this up in a small note:
https://www.satsignal.eu/raspberry-pi/Uputronics-RTC.html
Cheers,
David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv
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[ntp:questions] NTP not seeing servers with a 2-year offset, stand alone configuration
NTP doesn't work as expected when using PPS and GPSD alone, when there is a very large offset (2 years) between the host date/time (Raspberry Pi) and the GPS date/time. PPS and GPSD appear to be present (using "ppstest" and "ps-e | grep gpsd", and the ntpq display shows the PPS and GPS servers but with zero reach. This is with the Wi-Fi blocked on the RPi. There is a physical hardware clock on that system, which works correctly when the Wi-Fi is unblocked, but sometimes shows a data in February 2019 with the Wi-Fi blocked. The same system works correctly otherwise when unblocked. Even the HWCLOCK can be set and read. Does this ring any bells with anyone? Thanks, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PPS, prefer keywoard and redundant peers
On 24/11/2020 04:05, Scott wrote: Hi all, the documentation clearly states that for a PPS driver to work one needs to configure another peer as `prefer'. I have a set-up with PPS and three network (IP) peers, one of these marked preferred. 1) why can't the PPS signal be used to discipline all survivors (assuming they meet the requirements for PPS)? 2) if my preferred peer goes away, NTP will not use PPS at all (it looks like it becomes the system peer (*) then later a falseticker (x)). Is there any way to make PPS survive a prefer peer loss? Many thanks. Scott, I don't understand what you're expecting in (1). With (2),. you could simply mark all your peers as "prefer". Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Local Time NTP Server
On 14/09/2020 13:45, Rob van der Putten wrote: Hi there On 24/08/2020 16:07, William Unruh wrote: It was renamed because UTC has nothing to do with Greenwich. For historical reasons, the time at Greenwich is the same as UTC. They are not perfectly identical. The difference is however less then one second; GMT is mean solar time. UTC is TAI (atomic time) + leap seconds. Regards, Rob Whilst this may be true, in practice people use GMT when they mean UTC. BTW: GMT is mean solar time /at Greenwich/. What annoys me is when Raspberry Shake and others refer to "UTC time"! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] create charts
On 21/08/2020 12:01, thimoo...@gmail.com wrote: Op vrijdag 21 augustus 2020 om 12:52:49 UTC+2 schreef David Taylor: On 21/08/2020 11:39, thimoo...@gmail.com wrote: I have a question. how do you make a graph of your ntp server and is that possible i need a linux version The tools I use - MRTG and Perl - run on Linux. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] create charts
On 21/08/2020 11:39, thimoo...@gmail.com wrote: I have a question. how do you make a graph of your ntp server and is that possible One example is here: https://www.satsignal.eu/ntp/NTPandMRTG.html -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Performance estimation
On 17/06/2020 00:03, William Unruh wrote: Unless the cables are properly terminated at boththe gps receiver and the computer, this is probably not true. (the velocity of light may be under 5ns (ie less than 5 feet between the receiver and the computer) but the capacitive charging of the cable, etc if not properly terminated would produce a pulse with a rise time of much longer than that. Note that it is NOT the antenna that I am refering to, but the cable connecting the gps pps to the computer and the capacitance in the receiver in the computer and transmitter in the gps. [] Bill, this is a 10 cm ribbon cable at 3.3V TTL levels. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Performance estimation
On 16/06/2020 17:11, William Unruh wrote: [] The question then is how rapidly the system can respond to an interrupt,. This at least used to be of the order of a microsecond. Also, how logd does it take to read the clock with the kernel gettime routines. They all limit the accuracy of your clock using gps refclock > (and also how long the wire is between the gps unit and the computer) I quick it more a question of variance rather than the absolute time, but I agree with your comment. Again, with only microsecond reporting and today's processors it's difficult to measure. To the latter, cable length, well under 5 nanoseconds! https://store.uputronics.com/index.php?route=product/product&path=64&product_id=84 -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Performance estimation
Forgot the link: RasPi-1: https://www.satsignal.eu/mrtg/performance_raspi-1.php -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Performance estimation
On 16/06/2020 14:04, Miroslav Lichvar wrote: On 2020-06-16, David Taylor wrote: The clock on a Raspberry Pi ranges from 700 to 1500 MHz, so clock resolution is in the nanosecond range. For best timekeeping performance, you would want to set the CPU frequency to a fixed value. I would also like to see whether the characteristics of the GPS and its location make a measurable difference to the RPi's timekeeping. For example: is it better to have a GPS with 3 service capability at a location where the signal is poor, or is it masked by the RPi's performance? All this with kernel-mode PPS. The interrupt latency of the PPS timestamping is probably much larger than any errors related to GPS, so I'd say it doesn't matter. Oh, sorry, that's the CPU performance range between the models, from earliest to latest. Having said that, some of the [later?] models do operate a varying CPU frequency. Perhaps that's why the offset varies so little on my very earliest RPi: https://www.satsignal.eu/mrtg/performance_raspi-1.php I'm inclined to agree with you about interrupt latency, not to mention the Ethernet being over USB in the earlier models! Still nice to make measurements to see what can be achieved, and the principles are more widely applicable. Good lockdown learning! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Performance estimation
On 15/06/2020 19:00, David Woolley wrote: [] What is the clock resolution? If you try and measure jitters that aren't several times the resolution, they are not going to be particularly valid. If the hardware clock is almost dead on, and the peak to peak dither is just less than the resolution, there will be long periods in which it will read as as zero, even though it is actually close to one resolution unit. You could also get cases where dither was very low but read as one resolution unit for long periods. In fact, if it was possible to find tune the actual clock oscillator, during an ideal lock you would have peak to peak dither, as measured, of one or two resolution units, even though the actual phase noise was much less. (Arguably, a jitter that is less than the clock resolution will result in worse time accuracy than one that a few times it, as the clock resolution will not be dithered out. That makes the, normally unrealistic, assumption that the systematic error is less than the clock resolution.) The clock on a Raspberry Pi ranges from 700 to 1500 MHz, so clock resolution is in the nanosecond range. There is mention of 250 MHz as well, which would be 4 nanoseconds. It would be nice to see numbers which distinguish a little better than earlier RPi is "3" and more recent ones are "1"! I would also like to see whether the characteristics of the GPS and its location make a measurable difference to the RPi's timekeeping. For example: is it better to have a GPS with 3 service capability at a location where the signal is poor, or is it masked by the RPi's performance? All this with kernel-mode PPS. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Performance estimation
On 15/06/2020 19:58, William Unruh wrote: [] Why would it be useful? What are you trying to do. It is always better to first present the problem rather than trying to get people to improve your solution to an unknown problem. It's not a problem, simply trying to get a better understanding of what the variables are and whether they are useful to measure. If you want to call it a problem, call it the "Performance Estimation" problem. I've been measuring offset for some time, and Gary Miller suggested that jitter might also be a useful measure. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] List rejection!
On 15/06/2020 19:53, William Unruh wrote: [] And why would you think that posting it to the newsgroup would get the people in charge of the email list? Do you mean one of the mailing lists listed on https://lists.ntp.org/listinfo? Which one? There it says If you are having trouble using the lists, please contact mail...@lists.ntp.org. Have you tried that? Unfortunately, the error message you get doesn't indicate who to contact: ~~ You are not allowed to post to this mailing list From: a domain which publishes a DMARC policy of reject or quarantine, and your message has been automatically rejected. If you think that your messages are being rejected in error, contact the mailing list owner at %(listowner)s. ~~ So in the hope that %(listowner)s might be reading here -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Performance estimation
On 15/06/2020 16:10, Miroslav Lichvar wrote: On 2020-06-15, David Taylor wrote: [] The lightly-loaded Raspberry Pi cards are all showing low numbers of jitter, and it would be really useful to get that in more than three decimal places of milliseconds. You would probably need to patch ntpd to report the values in a better precision. Thanks! I recall talking about this some time back and wondered whether anything had actually been done. There was talk of a "wide" version but while that parameter is accepted it doesn't affect the output from "-crv", or "-pn". -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Performance estimation
On 15/06/2020 08:33, Miroslav Lichvar wrote: On 2020-06-14, David Taylor wrote: When using the ntpq -crv command, which is the better measure of system performance - clk_jitter or sys_jitter? I've look for the definitions and I'm thinking sys_jitter but perhaps someone could please remind me of the difference? clk_jitter seems to be the jitter of the system clock as it is being updated with offsets, and sys_jitter seems to be the jitter of the selected peer, or the combined peers after clustering. https://www.eecis.udel.edu/~mills/ntp/html/cluster.html == [Been trying to send through e-mail to ntp-questions, but anything I send gets rejected!] Thanks, Miroslav. Right! I'm not sure which I should be measuring so I plotted both: https://www.satsignal.eu/mrtg/performance_ntp_jitter.php Blue is system jitter, green is clock jitter. The lightly-loaded Raspberry Pi cards are all showing low numbers of jitter, and it would be really useful to get that in more than three decimal places of milliseconds. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] List rejection!
On 15/06/2020 14:50, William Unruh wrote: On 2020-06-15, David Taylor wrote: Once again, I tried to reply on the e-mail link but the message was rejected, Could the mailing list admin please set it so that: No idea what you wanted to do. If you wanted to reply to the poster's email, they may--like you -- have an invalid email. Also your email is not either of the two below-- yours ends in .invalid. david-tay...@blueyonder.co.uk gm8...@yahoo.co.uk are allowed through, please. This hindrance to communication is most tirecome! Allowed through where? Through the e-mail interface, not the NNTP. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] List rejection!
Once again, I tried to reply on the e-mail link but the message was rejected, Could the mailing list admin please set it so that: david-tay...@blueyonder.co.uk gm8...@yahoo.co.uk are allowed through, please. This hindrance to communication is most tirecome! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Performance estimation
When using the ntpq -crv command, which is the better measure of system performance - clk_jitter or sys_jitter? I've look for the definitions and I'm thinking sys_jitter but perhaps someone could please remind me of the difference? Are the units for sys/clk_jitter in milliseconds. For my application, more than three decimal digitals would be helpful, i.e. down to nanoseconds. Is there a way to get that from a command-line query? [Similar questions posted to questions@... haven't appeared - yet.] -- Thanks, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Trying to reply to an NTP Questions request I get this
On 21/08/2019 21:01, David Woolley wrote: On 21/08/2019 17:42, David Taylor wrote: You are not allowed to post to this mailing list From: a domain which publishes a DMARC policy of reject or quarantine, blueyonder doesn't appear to publish any DMARC policy. Did you actually use a blueyonder address as the header From:? It is also possible that they tried one and it broke too many things. They do seem to have a DKIM signature that includes the subject, so any mailing list that rewrites the subject will break the signature. Most mailing lists rewrite the subject, if it doesn't have the list tag in it. I imagine the list software isn't doing a fully analysis of DMARC and DKIM to see if relayed mail will fail, but just looking for specific things in the DMARC policy to know whether a failure would be a problem for the list. I'm assuming it is well behaved and rewrites the envelope from so that SPF will pass the mail. Otherwise it will be generating SPF failures, downstream. Thanks for your comments. As a major ISP, I would expect Virgin Media (a.k.a. blueyonder) to get things right - if only! Yes, I simply used my blueyonder e-mail which has worked without issue in the past. I've been advised to use a gmail address instead which I've now done, and await to see whether I now get two copies of the messages. I did try to contact the list manager (johnl@.) but mail to him got a "retry timeout exceeded"! What a mess! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Trying to reply to an NTP Questions request I get this
Trying to reply to an NTP Questions request I get this: You are not allowed to post to this mailing list From: a domain which publishes a DMARC policy of reject or quarantine, and your message has been automatically rejected. If you think that your messages are being rejected in error, contact the mailing list owner at %(listowner)s. As I have no control over my ISP's domain, (blueyonder co uk) could the list owner please resolve this so that I can help the person with the issue? Of course, I get the same message trying to contact the list owner by e-mail, hence the post here -- Thanks, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Shall I use a fudge on PPS?
On 16/07/2019 21:19, Andreas Mattheiss wrote: Hello, I have a cheap GPS hooked onto my PC via a MAX232 level converter - the PPS goes directly into the DCD pin of a native serial port. Everything is fine; after some time ntpd locks onto the PPS signal, and any other servers from the net show a small offset in ntpq -p. What is the correct way of dealing with this? We are talking about 3 ms here. Is it appropriate to use a fudge on the PPS to bring it in line with the mean of a handfull of other servers from the net, or is is more appropriate to use the PPS's pings face value, not using any fudge? Thanks, regards Andreas Andreas, I would suspect asymmetric network delays as Bill commented. I see this all the time, and would trust my PPS far more than some network, especially any consumer-grade wide-area network. Here's what I see one PC: C:\Windows\System32>ntpq -pn kiruna remote refid st t when poll reach delay offset jitter == o127.127.22.1.uPPS. 0 l- 16 3770.0000.026 0.013 x127.127.20.1.NMEA. 0 l1 16 3770.000 -53.013 16.730 *192.168.0.20.GPS.1 u 12 32 3770.2730.007 0.023 +192.168.0.3 .kPPS. 1 u 25 32 3770.1710.008 0.039 +192.168.0.71.kPPS. 1 u 26 32 3770.5240.010 0.012 uk.pool.ntp.org .POOL. 16 p- 6400.0000.000 0.000 -83.170.75.28194.80.204.184 2 u 41 64 377 17.4592.596 1.149 -37.220.20.1285.199.214.982 u 51 64 377 20.0212.315 1.113 -89.238.136.135 131.188.3.2232 u 22 64 377 12.8052.520 0.857 -195.171.43.10 .PPS.1 u 12 64 153 27.4542.916 0.718 This PC has a PS reference. Within the LAN other PPS servers show offsets up to 26 microseconds. The servers from the WAN have offsets of +2.3 to +2.9 milliseconds. The WAN is supposedly 200 Mbps down, and 12Mbps up - at the best of times! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Garmin LVC 18x jitter problem
On 10/07/2019 22:15, Michael Haardt wrote: I use a Garmin LVC 18x with a Raspberry Pi, process NMEA with gpsd (SHM driver) and acess PPS by GPIO (kernel PPS driver). gpsd allows monitoring and passing PPS right into ntpd avoids gpsd conversion of PPS. Sometimes this works, but then there are times where both clocks are thrown out as falsetickers. I believe that's due to the strange jitter behaviour of the NMEA data. If I understood the clock selection right, then basically the measured jitter forms an interval around the offset and the intersection interval is the root dispersion. Should the NMEA clock have no intersection with the used PPS clock, it is a falseticker, but since PPS depends on it, PPS is so as well. I graphed offset and jitter from two days peerstats where I was locked on PPS (tos mindist 0.1) and the system ran stable without the need to adjust the crystal frequency at constant environment temperature. The first day was mostly fine, but in the middle of the second day, the GPS jittered really bad and there are many occasions where the jitter interval did not intersect with 0. The ntpd jitter estimation works as expected for a normal distribution, but the distribution is clearly different: http://www.moria.de/~michael/tmp/offset.svg http://www.moria.de/~michael/tmp/jitter.svg Using the tos mindist extends the intersection interval, but that effects the root dispersion. That's correct if it is needed to have an intersection between different clocks of low jitter, but in my case the problem is a wrong (too low) jitter estimation of a clock I only need as PPS reference. Is there any way to specify the precision manually, like fudge minjitter? Clearly the jitter suffices to keep the PPS clock running and I would like to have PPS determine the root dispersion, because the PPS clock has a jitter of 4 us. This problem seems to have come up a number of times in the past, but I never saw the root dispersion impact of tos mindist mentioned and I suspect in a number of cases configuring a minimal jitter would have been a better solution. Michael Michael, I'm not an expert in this, but the timing seems to be the same in both graphs, the problem occurring around 8000. Could that be due to someone with a GPS jammer parking nearby? I always try and have more than just the NMEA source as a "prefer" server if possible, something from the Internet will be much more reliable than the serial data! Try adding a "pool" directive or some known good servers. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Some servers returning the wrong time
On 03/07/2019 10:52, Roger wrote: On Wed, 3 Jul 2019 00:56:08 -0700 (PDT), rickylje...@gmail.com wrote: Server 206.108.0.131 which is part of 0.pool.ntp.org is returning a date and time that is off around 11 hours. Trying to find any details of why this would be happening. The change was very sudden https://www.pool.ntp.org/scores/206.108.0.131 Yes! It makes you wonder how many servers they have, doesn't it? Mike Cook also confirmed that it is now OK - thanks. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Some servers returning the wrong time
On 03/07/2019 08:56, rickylje...@gmail.com wrote: Server 206.108.0.131 which is part of 0.pool.ntp.org is returning a date and time that is off around 11 hours. Trying to find any details of why this would be happening. GPS week number roll-over effect, or something related? Can't run ntpq against it from here. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Time server question
On 25/06/2019 01:33, Chris wrote: [] Thanks for all the replies. I guess the next thing to do is to build a working system, then evaluate to see how it can be improved. All the kit is in the same rack and with dedicated hardware interfaces, network latency shouldn't be a problem. This is effectively a real time requirement, so any code running needs to be consistent in terms of response time to minimise jitter on the timing. Need to get a feel for acceptable delay and response times, so will look to see what others have done in the past. I like the idea of using a 1 pps signal from the gps for fine tuning. Rough time and date via the network ntp and the 1pps to fine tune it. That could maintain the stratum 1 timing quality, as the 1pps is generally within 10's of nS of UTC, but need to look into how ntpd would handle that and also how to introduce that into the system. Already use an ex telco gps for a lab frequency standard, but of course, frequency != time of day. A dedicated embedded solution might be the best bet, but other options might include a cheap netgear router to provide the isolation, as it would only be handling ntp packets at low and consistent system and network load. Nothing is ever as easy as it seems, as usual... Chris Chris, would one or more of these help? http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=272 No OS to get in the way. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Fine tuning ntp.conf
On 27/04/2019 23:29, jelisko...@gmail.com wrote: [] I am thinking of buying this https://www.ebay.com/itm/U-Blox-LEA-5T-high-precision-timing-GPS-module-dev-board-1PPS-USB-RS232-ntp-ser/263546760982 With this antenna https://www.ebay.com/itm/28dB-LNA-Gain-1575-42MHz-Male-SMA-Male-GPS-Active-Antenna-Stronger-Singal/401331172214 It should work, not tested here, but be sure that you have a good location for the antenna - south facing window or outdoors. These antennas work better with a ground plane, something like half-wave square or bigger. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Fine tuning ntp.conf
On 27/04/2019 17:37, William Unruh wrote: [] On the subject of gps/pps receivers, since the Sure OEM board seems to have disappeared, what is the current recommendation for a cheap gps/pps board to attach to your computer? (the above is not cheap-- on the order of $500, rather than $50) Something happened to the previous As mentioned on my Web page: https://www.satsignal.eu/ntp/Sure-GPS.htm you can use a cheap module from eBay, or perhaps an Adafruit one, and you could need a TTL to RS-232 voltage level converter: https://www.adafruit.com/product/746 https://www.amazon.co.uk/gp/product/B00EJ9NAKA I found that the PPS signal was OK at TTL level. The Leo Bodnar unit would be ideal as a central server for a small group or bigger, and has the advantage of excellent support. The cost is appropriate for the quality level of the unit, but it would likely be overkill for a single PC. http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=120&products_id=272 -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Fine tuning ntp.conf
On 26/04/2019 18:39, William Unruh wrote: [] One problem with the pool is that the servers have varying accuracy. If you have carefully chosen your servers as having low uncertainty, then your list might be better. But if you simply chose them randomly, then the pool will probably be just as good. Yes, although in practice I've not found this to be a problem. Using the pool can be lower maintenance too, let NTP do the monitoring. If accuracy is that critical you should consider having your own stratum-1 server - GPS/PPS devices are inexpensive today. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Fine tuning ntp.conf
On 26/04/2019 21:27, jelisko...@gmail.com wrote: [] I think that you are mistaken. " The servers joining should not have pool.ntp.org as their upstream server(s), but should configure some good servers manually (those servers may be chosen from the pool. The point is that they are chosen statically instead of assigned randomly at each server restart " - https://www.ntppool.org/en/join.html As I read it, that refers to pool servers themselves. Their clients, your PC, will choose between the available pool servers for best results over time if you use the pool directive. My suggestion was to avoid very well-known servers which may well be stratum-1, but which are are so busy that they provide less accuracy than pool servers, and to get the benefit of automatic removal and replacement of dead servers. If accuracy is /that/ critical, you should consider either adding a PPS feed to your own PC, or using a GPS/PPS device with good holdover to your network, such as: http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=120&products_id=272 It all depends on your requirements. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Fine tuning ntp.conf
On 26/04/2019 14:31, jelisko...@gmail.com wrote: Hi guys, This is my config file for my NTP Stratum 2 server. Any suggestion for fine tuning will be appreciated. [] # Use public servers from the pool.ntp.org project. # Please consider joining the pool (http://www.pool.ntp.org/join.html). #server ntp.svilengrad.eu iburst #server ntp.fizyka.umk.pl iburst server ntp.bsdbg.net iburst server ptbtime1.ptb.de iburst server zeit.fu-berlin.de iburst server ntp0.fau.de iburst [] One comment - why not use the pool servers, as suggested? Replace your four lines with: pool de.pool.ntp.org minpoll 6 maxpoll 7 iburst You may find that some of the public servers you list may be overloaded, or come and go from time to time - the "pool" directive takes care of vanishing and overloaded servers. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] restrict: ignoring line %u, address/host '%s' unusable.
On 12/09/2018 08:06, Jakob Bohm wrote: NTP 4.2.8p10+dfsg-3+deb9u2 (Debian packaged with backported security fixes), on a dual stack (IPv4+IPv6) machine logs the following error messages for each netmask specific restrict line, and does seem to ignore the lines or otherwise enforce incorrect limits: ntpd[]: restrict: ignoring line %u, address/host '%s' unusable. Looking at github, this seems to happen when a line doesn't match the address family (IPv4 or IPv6) of a loop iteration in the config code. Is this a general NTP bug or did the Debian maintainer get a patch wrong. Enjoy Jakob Isn't NTP 4.2.8p12 the current version? 4.2.8p10 was March last year, sigh! Hope you find the issue. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Windows binaries for ntp-4.2.8p12
There has been an update to NTP to ntp-4.2.8p12 and I've compiled a version for Windows (XP up to Win-10-32/64) here: http://www.satsignal.eu/ntp/x86/index.html Note that you might need to update your OpenSSL too, details on that Web page. Thanks to @NTP for the update. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP rejecting SHM for NMEA GPS and PPS
On 10/08/2018 23:16, na...@datacloud.com wrote: I forgot to mention that I am using Ubuntu 16.04 and the GPS receiver is connected via USB USB is not the best to get good results. You need to connect the PPS signal directly to a port on the device - typically the CD (carrier detect) line on a _true_ serial port is used. Likely the serial-over-USB is rejected because of excessive jitter. I don't know whether you may have your "prefer" in the wrong place without looking in detail. You need the "prefer" against a server which will provide the coarse seconds (i.e. a clock) otherwise the PPS edge will not be recognised (as NTP needs both coarse time and the exact second). You may, or may not, be correct. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] u-blox reference clock driver
On 11/08/2018 12:29, Terje Mathisen wrote: David Taylor wrote: This was posted by lu...@fridolin.com on the NTP hackers list, just in case you missed it. ~ Hi, I've been writing a reference driver for u-blox GPS receivers as part of my master's thesis and thought ntp hackers might be interested in it. Additionally to normal PPS operation this driver can make use of the u-blox's "Timemark" functionality. It does this by enabling the PPSAPI echo, which generates an echo pulse right after receiving a PPS pulse. This echo is connected to EXTINT0 on the u-blox, where it is timestamped. So now I have the PPS timestamp as a local time and the timemark as the receiver time to calculate an offset. The cool thing about this is, that the offset does not include the local interrupt latency anymore, which leads to less jitter. This is indeed cool, do you have any graphs/stats for the actual/remaining jitter? Terje There are some histograms in his thesis for various conditions of the Raspberry Pi which I saw on a quick glance. Take a look at Chapter 4, page 35. Graphs on p.40 onwards. https://wwwcip.informatik.uni-erlangen.de/~in18otin/thesis.pdf -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] u-blox reference clock driver
This was posted by lu...@fridolin.com on the NTP hackers list, just in case you missed it. ~ Hi, I've been writing a reference driver for u-blox GPS receivers as part of my master's thesis and thought ntp hackers might be interested in it. Additionally to normal PPS operation this driver can make use of the u-blox's "Timemark" functionality. It does this by enabling the PPSAPI echo, which generates an echo pulse right after receiving a PPS pulse. This echo is connected to EXTINT0 on the u-blox, where it is timestamped. So now I have the PPS timestamp as a local time and the timemark as the receiver time to calculate an offset. The cool thing about this is, that the offset does not include the local interrupt latency anymore, which leads to less jitter. Here's the driver: https://gitlab.cs.fau.de/luksen/ntp-ubx/blob/ubx/ntpd/refclock_ubx.c The echo/timemark feature requires kernel patches on Linux (with gpio pins) and FreeBSD (parallel port). It's probably easiest to test on a Raspberry Pi with the Linux patch and via GPIO pins. Linux patch: https://gitlab.cs.fau.de/snippets/28 FreeBSD patch: https://gitlab.cs.fau.de/snippets/29 I originally tried to send this message some time ago but it seems like there were some problems with the mailing list. By now the thesis is finished and you can find it here: https://wwwcip.informatik.uni-erlangen.de/~in18otin/thesis.pdf --Lukas ~ -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Difference between offset (ntpq -p) and offset (ntpq -crv)
On 02/08/2018 09:14, David Woolley wrote: On 01/08/18 19:32, David Taylor wrote: Would I be right in thinking of the "*" line as simply being the offset from that particular server, and the "system" variable as being the offset from some virtual internal clock which ntp has as its best estimate of the correct time (e.g. UTC). That cannot be correct, as the other side of the comparison is that best estimate of system time and the result would always be zero. Without digging into the code, my guess is that it is the offset from the weighted average of the last reading from all the true chimers. Thanks, David. Weighted average I can accept unless someone knows better. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Difference between offset (ntpq -p) and offset (ntpq -crv)
I was writing a small script to check on offset, and noticed that the
offset from the selected server ("*" line in the tally list from ntpq
-p) differs considerably from the offset reported as a "system" variable
(ntpq -crv).
Would I be right in thinking of the "*" line as simply being the offset
from that particular server, and the "system" variable as being the
offset from some virtual internal clock which ntp has as its best
estimate of the correct time (e.g. UTC).
This was to answer someone's question: is the NTP on that system working
as expected, by comparing the offset with a pre-defined threshold.
--
Thanks,
David
Web: http://www.satsignal.eu
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[ntp:questions] Determining the offset of GPS serial data automatically - a Linux script
Angelo Mileto recently sent me some notes about determining the offset of serial GPS data automatically using a Linux script. This value is used as the time1 fudge factor. I hope you find it useful. My thanks to Angelo! https://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#average -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] shm + pps calibration
On 05/07/2018 21:30, Daniel Gearty wrote: server 127.127.20.3 iburst minpoll 3 mode 17 # COM3, 8 second polling, NMEA GPRMC, 9600 bps, NaviSys GR-8013W u-blox M8 USB PPS GPS fudge 127.127.20.3 time1 0.000142 time2 0.11 flag1 1 flag2 1 flag3 0 # PPS offset, NMEA offset, enable PPS, pulse on falling edge, disable kernel PPS I am using a u-blox M8. I had trouble with it until I realized that the pulse is on the falling edge rather than the default of the rising edge. I used a u-blox utility to see timestamps for the NMEA GPRMC sentence coming through. It took about a tenth of a second. If it is accurate to within four tenths of a second, it works. It not, then it does not work. Barring access to a more accurate clock, PPS offset is a blind guess. All I do is offset by an average of the NTP loopstats offset over time. I use 142 microseconds. I've compared a number of GSP/PPS sources using an oscilloscope and the PPS offset between them is usually within 100 nanoseconds, so I would be surprised if the PPS leading edge is as much as 142 microseconds out. With a Raspberry Pi, I typically I see offsets reported by ntpq -pn well under 20 microseconds: C:\Windows\System32>ntpq -pn raspi-1 remote refid st t when poll reach delay offset jitter == o127.127.22.0.kPPS. 0 l 13 16 3770.000 -0.001 0.004 127.127.28.0.GPSD. 0 l 12 16 3770.000 367.025 5.593 *192.168.0.3 .kPPS. 1 u6 32 3770.5420.054 0.008 . . https://www.satsignal.eu/mrtg/raspi1_ntp.html -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] shm + pps calibration
On 07/07/2018 18:10, William Unruh wrote: On 2018-07-07, David Taylor wrote: [] On one PC I'm using an add-in PCIe card, a TTL-RS232 converter (tried without but the signal levels were too low) and a Chinese module sitting That is really unusual. Most serial cards now will happily use TTL levels. The converter may (or may not) introduce delays to the pps signal. If they are sub usec it probably does not matter. Yes, Bill, that surprised me as well! Adding the level converter (a cheap Chinese board) solved the issue (no data seen on the serial port). As this was for a Windows PC, a sub-microsecond delay didn't matter. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] shm + pps calibration
On 06/07/2018 21:18, Daniel Gearty wrote: In my case, I attribute the PPS delay to the serial to USB 1.1 conversion of the Prolific PL2303HXD in my NaviSys GR-8013W GPS. The offset bounces around within +/- 0.5 msec. It appears the initial PPS offset should be zero if you receive your PPS signal directly from a proper serial port. I am using NTP "Generic NMEA GPS Receiver" driver 20 with the Windows loopback driver. ggavi is using "PPS Clock Discipline" driver 22 for PPS, but perhaps should be using "Shared Memory Driver" driver 28 for both NMEA and PPS. http://www.catb.org/gpsd/gpsd-time-service-howto.html#_feeding_ntpd_from_gpsd Another, newer driver for NTPD to receive time from gpsd is "GPSD NG client driver" driver 46. http://doc.ntp.org/current-stable/drivers/driver46.html Although I wonder whether chronyd receiving time from gpsd via a socket has the best NTP performance. https://chrony.tuxfamily.org/doc/3.3/chrony.conf.html Using different software (Chrony or gpsd) is unlikely to improve performance which is inherently limited by the serial-USB conversion, unless someone were to write a special driver to average out the USB jitter. NTP will do that to an extent, of course. For best NTP performance, if you aren't using a portable PC (so no serial port), check whether your motherboard has a serial port header, or get an add-in PCIe serial port and swap the GPS for one which has a real PPS line. Likely even the low-cost Chinese ones will be good enough. On one PC I'm using an add-in PCIe card, a TTL-RS232 converter (tried without but the signal levels were too low) and a Chinese module sitting on the bench. Needed to add one wire from the u-blox module's PPS pin: https://www.satsignal.eu/ntp/NEO-6M-under-initial-test.jpg https://www.satsignal.eu/ntp/RasPi-3-with-u-blox-RX.jpg but you could avoid that with the Adafruit module: https://www.adafruit.com/product/746 Here's a link to the PC's performance: https://www.satsignal.eu/mrtg/lund-ntp-2.html The variation on that PC is likely due to the CPU temperature as the load varies with receiving new Sentinel-3A satellite data every orbit (101 minutes). -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] does this make sense?
On 04/04/2018 20:47, Maria Iano wrote: Thanks William, I will go with GPS. Maria That's a good choice. These boxes are low-cost (but not yet multiple GNSS systems - check with the vendor), and have good hold-over in the event of GPS failure: http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=272 -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] does this make sense?
On 04/04/2018 17:29, Maria Iano wrote: I'm purchasing ntp appliances to put into three datacenters. Does it make sense to purchase two that use GPS and two that use WWVB, and configure them as peers? Thanks, Maria Probably, yes, although these days I would suggest that GPS (including GLONASS and Galileo) is sufficiently reliable. WWVB will not be as accurate and may be subject to local interference. I've seen GPS fail due to local jamming (deliberate or accidental), but if you separate out the GPS devices across three locations you should cover yourself against that. Be sure to get devices which cover all three GPS services I listed to guard against single service failures (which have also happened at least once in the past). What accuracy do you need? Microseconds, milliseconds, or? -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ntp.ymartin.com
On 28/03/2018 21:31, Yves Martin wrote: I've installed my own ntp server since a year now, using a NTP100 server sync with an external GPS antenna. Just need to know if it's reachable from outside. Thanks. ntp.ymartin.com YM Yves, this is what I see (edited for brevity): ~ C:\Windows\System32>ntpdate -q ntp.ymartin.com server 45.73.0.50, stratum 1, offset -0.000736, delay 0.13692 ~ so it's reachable. The offset looks much higher than I see on the Linux boxes here (e.g. server 192.168.0.3, stratum 1, offset 0.07, delay 0.02594). -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] ntp-4.2.8p11 for Windows
Folks, There has been an update to NTP to ntp-4.2.8p11 and I've compiled a version for Windows (XP up to Win-10-32/64) here: http://www.satsignal.eu/ntp/x86/index.html Note that you may need to update your OpenSSL too, details on that Web page. Thanks to @NTP for the update and to Juergen Perlinger for helping resolve the initial failure to compile on my system. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Problems with Sure OEM pps gps
On 19/11/2017 06:29, William Unruh wrote: []> t but it is annoying to keep seeing 8 or more postings only to have all of them killed. It is bizzare, and wonder if there is some way of getting google to kill that account. Can you check other devices in the same location? I've seen something similar happen when a GPS jamming device was (I guess) parked nearby. You might also check that the serial feed is still OK. I have no other devices in the area. All I use is the PPS on that gps receiver, not the nmea. But yes, I do believe it is OK. It is hard to see what could happen in an empty office at 4PM. I will see if I can find another gps receiver. I have just two e-mail addresses set to filter and delete. I was thinking of a mobile phone as the "test" GPS receiver. If you have an Android phone it will be able to see the individual signal strengths. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Problems with Sure OEM pps gps
On 18/11/2017 21:55, William Unruh wrote: I am having sudden problems on my system with a Sure GPS with PPS. I am running chrony, using a serial port to bring in the PPS signal. Everything was working well-- the rms timing on the pulse was about 1usec. Suddenly on Nov 18 at very close to 00:00:00UTC the timing went to hell, and the rpms is now at 20us-- the individual pulses have an offset that fluctuates between about 50us, and -50us. Is there any hint as to what I could do to track down the problem. Could it be the sattelites (ie the timing has suddenly gone from ns to tens of usec for some reason? But if this were true I would have expected to hear many many loud screams here.) Or the gps receiver? (again, unlikely I would think). Or the serial card? or chrony? Or the computer clock? (the computer was not rebooted anywhere around that date). : By the way, what in the world has happened to this newsgroup? I am getting about 1 valid message to over 100 Case Solutions? Bill, You need to add a filter to your news feed to remove the unwanted postings. Can you check other devices in the same location? I've seen something similar happen when a GPS jamming device was (I guess) parked nearby. You might also check that the serial feed is still OK. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP with Meinberg NTP for Windows - Looking to use 1PPS source from GPS - Serialpps?
On 03/11/2017 00:23, Geoff Roberts wrote: Never mind. I found it. Nice 64 bit signed Kernel mode version too. http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html#Win-7-64-bit Haven't tried it on win10 yet but should work. Geoff Yes, the driver works on Windows-10. If you have a non-standard COM port (e.g. an add-in board rather than a port on the motherboard), the "loopback" driver works almost as well and doesn't require kernel mode and a reboot to pick up a modified serial.sys. On a very heavily loaded system you'll notice the poorer performance of the user-mode loopback DLL. You can get an idea of the performance here - PCs Lund and Kiruna are "loopback": http://www.satsignal.eu/mrtg/performance_ntp.php#windows-stratum-1 -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] false ticker after GPS coldreset
On 01/11/2017 11:46, valizadeh...@gmail.com wrote: []> local lcok is there because my system is not connected to internet and i need to have the hwclock to keep the time during power-offs,i have disabled the pre installed fakeclock and used an I2c connected battery backed up RTC chip. the local clock is been updated at start up from the hwclock and hwclock itself is synchronized via ntp itself. so the server 127.127.1.1 is my hwclock :) am i right ? or shall i used another trick to utilize hwclock ;) [] There are issues with different versions of Linux behaving in different ways and using different scheduling programs which may require patient investigation to resolve. poor me then :( I've not added an RTC to my Raspberry Pi cards, so I can't help there. There's no RTC in the RPi itself. The RPi needs NTP to set its time at start-up. I don't know how the OS would set your particular RTC to I can't help there, but presumably there is a driver provided? I recall that action may have to be taken to make Linux keep the RTC updated regularly, but that's outside the scope of my knowledge. I've just downloaded the latest Linux for the RPi, but the particular hardware I'll have connected (MMDVM_HS HAT) takes control of the serial port lines, so I won't be able to add my usual GPS device (Uputronics) for precise timekeeping, and it will have to be NTP over Wi-Fi. I might see whether you can simply add the PPS signal without using GPSD. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] false ticker after GPS coldreset
On 31/10/2017 08:50, valizade...@gmail.com wrote: server 127.127.1.1 minpoll 3 maxpoll 4 #hwcloak fudge 127.127.1.1 stratum 3 As Bill says, get rid of the local clock, and add some Internet sources. That way you can check whether your GPS is grossly wrong. The reach value seem wrong as well. Place your GPS antenna where you are sure of a good signal - you can check this with an Android mobile phone (Apple doesn't allow programs to access this information, sigh!). Note that I have been able to get such a stand-alone configuration working (for when you are in the field without Internet access). See: http://www.satsignal.eu/ntp/Raspberry-Pi-quickstart.html#stand-alone There are issues with different versions of Linux behaving in different ways and using different scheduling programs which may require patient investigation to resolve. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Errors in "restrict" lines
Hi, Perhaps the problem comes from the first line when it's asked: restrict source ... query It is possible that the word 'query' is not recognize, usually 'restrict' command is used to disable services and not to enable them. Best, Jean-Michel Thanks Jean-Michel and Harlan. Yes, both the query and the peer are wrong. This dates back to a quite early Raspberry Pi which must have been set up some four years back. Looking at the guidelines on my own Web site I see a correct version of the restrict lines! Shame on me! BTW: Harlan, I got your direct e-mail, for which, thanks, but I see nothing Usenet server I use (Eternal September). -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Errors in "restrict" lines
Folks, I will be the first to admit that I'm not very conversant with "restrict" lines, so perhaps the following will be obvious to you! I have in lines 34 onwards of my ntp.conf: # Suggestions for NTP restrictions: restrict source notrap nomodify nopeer query restrict 127.0.0.1 restrict ::1 restrict 192.168.0.0 mask 255.255.255.0 peer and NTP is giving the following error messages: Jun 26 05:58:10 raspi-4 ntpd[2776]: line 35 column 29 syntax error, unexpected T_String, expecting T_EOC Jun 26 05:58:10 raspi-4 ntpd[2776]: syntax error in /etc/ntp.conf line 35, column 29 Jun 26 05:58:10 raspi-4 ntpd[2776]: line 38 column 32 syntax error, unexpected T_Peer, expecting T_EOC Jun 26 05:58:10 raspi-4 ntpd[2776]: syntax error in /etc/ntp.conf line 38, column 32 I am at a loss to explain these errors Can you help? If it's some non-printing character, how in Debian (Raspbian) Linux could I dump the file in hex to check for that? -- Thanks, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] GPS-PPS, standalone server. NTP
On 06/06/2017 13:11, girin...@gmail.com wrote: [] Some GPS will continue to deliver a PPS signal even if the lock is lost. I'm thinking particularly about the Garmin 18xLVC where it is clearly indicated in the documentation (4.4.1): 'After the initial position fix has been calculated, the PPS signal is generated and continues until the unit is powered down.' With the use of that 'kind of' GPS, ntpd will continue to provide time service. As I understand it, NTP will only continue to provide a service if it has other "time-of-day" sources available. Should the NMEA output (as the only time-of-day source) become invalid, NTP would reject it, and gradually ramp itself up to stratum-16 so as to become invalid as a server to its clients. [1 - I'm unsure off the top of my head what NTP checks to know whether NMEA is valid or not. 2 - I wonder what the drift in the GPS 18x LVC is when unlocked?] -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] GPS-PPS, standalone server. NTP
On 05/06/2017 22:53, Jakob Bohm wrote: [] Note that any failure in the GPS/GNSS radio hardware that actually provides both the PPS pulses and the NMEA messages would be a failure of both "ntpd sources". Thus such a failure of NMEA+PPS would be more common than a failure of NMEA or PPS alone. Enjoy Jakob .. and one failure experienced here was the presence nearby (RF-wise) of a GPS jammer. All GPS receivers lost lock, PPS and NMEA. Interesting to note which continued to provide an /unlocked/ PPS signal! The PCs continued to sync with the Internet alone. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP 4.2.8p10 released
On 26/05/2017 12:59, gaurav10ni...@gmail.com wrote: []> Hi David, I want to get offset between 0.5-2 ms. Can it be achieved using meinberg application? If yes, Kindly share the parameters required to be changed to get offset value in the required range. Regards, Gaurav Gaurav, As with many things, "it depends". Here are my offsets with NTP and Windows, using a PPS signal from a GPS device: http://www.satsignal.eu/mrtg/performance_ntp.php#windows-stratum-1 - provide good sky view for the GPS receiver. - use Windows 10 (Windows-8 also acceptable). - light, constant load. - keep the temperature as constant as you can. Is the performance show good enough? See my Web page for the parameters I use, but if you have a PPS source that's usually good enough. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP under AIX?
On 19/05/2017 07:01, Hans Jørgen Jakobsen wrote: On Thu, 18 May 2017 13:24:17 +0100, David Taylor wrote: You could get a dedicated NTP box such as: http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=272 and scatter a few or a dozen around your enterprise. Brand new hardware! From manual "Currently IPv6 is not supported." That has been a showstopper for me testing what otherwise looks nice. /hjj I suggest you contact Leo Bodnar and let him know - if you haven't already done so. Likely he would welcome extra sales! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP under AIX?
On 16/05/2017 19:53, Greg Moeller wrote: On Tuesday, May 16, 2017 at 10:37:55 AM UTC-5, Greg Moeller wrote: Has anyone come across the advisability of running an enterprise-wide NTP server under an AIX LPAR? We're currently running NTP on old Intel hardware and the company policy is to refresh hardware on a regular basis. It seems a waste to buy several new servers if we could just put the NTP service on an AIX LPAR. I'm at a large company, serving NTP to over >1000 systems. Policy is that we can't have old hardware, so they will spend several thousand $$ on servers to run a single process. (we're an IBM/Lenovo based shop) Technically, yes, this is a virtual machine, but this is on 250K$+ hardware, not something like ESXi or Xen. (and CPU/RAM/hardware can be dedicated to the LPAR if needed) These boxes are meant for heavy lifting, the same type of frames power AIX, iSeries, IBM mainframe, and Watson. Is there a way to test? It seems like I'm heading into the unknown here. :) You could get a dedicated NTP box such as: http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=272 and scatter a few or a dozen around your enterprise. Brand new hardware! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP 4.2.8p10 released
On 12/05/2017 06:33, Jakob Bohm wrote: [] Note that all recent/current versions of the Windows Time Service are in fact SNTP/NTP implementations, with quality of implementation improving in newer versions. Old (now unsupported) versions of the Windows Time Service violated the SNTP/NTP specification in ways that required special workarounds in standard NTP servers. Even older implementations that didn't even include a service named "windows time service" used simplistic time queries over the SMB protocol. Besides being included with the OS, the "windows time service" typically defaults to imposing a much lower load on the selected time source, by using much longer poll intervals. In "Active Directory" (Windows 2000 and later) setups, there is also a dead simple automatic configuration, where each machine simply syncs against it's nearest "upstream" in the authentication/management hierarchy, limiting practical management work to machines that have no such "upstream", such as the 2 to 4 machines at the top of the tree. And of cause machines needing more precise time than needed by the basic Windows functions. Enjoy Jakob If the Windows Time Service is good enough for your needs, then use it. Multi-platform operation, ease of management, monitoring, accuracy, ability to accept reference clocks make the reference NTP my preferred choice for Windows. Cheers, David -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP 4.2.8p10 released
On 07/04/2017 08:33, seema pandhre wrote: On Wednesday, March 22, 2017 at 6:57:36 PM UTC+5:30, David Taylor wrote: NTP 4.2.8p10 released Windows binaries working on Windows-XP SP3 & later - download: http://www.satsignal.eu/ntp/x86/index.html Source: http://archive.ntp.org/ntp4/ntp-4.2/ntp-4.2.8p10.tar.gz -- Cheers, David Web: http://www.satsignal.eu Hi David, Do you run the tests for ntp on Linux box as well? Can you please help me with its steps. I mean the tests folder which is available in ntp source. I run NTP on x86 and ARM Linux boxes: http://www.satsignal.eu/mrtg/performance_ntp.php#versions but my tests are very simple - does the software run? - is the output of "ntpq -crv -pn" as expected? - is the timekeeping steady? - is there an obvious memory leak? -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP 4.2.8p10 released
On 27/03/2017 22:34, Dan Gearty wrote: Hi David, that is interesting that the problem does not manifest across the board given Martin's description of the bug. I am using the Meinberg build on Windows 10 Pro. I had previously been depending upon the environment variable. PPSAPI_DLLS=loopback-ppsapi-provider.dll Yes, with five PCs here I would have expected at least one of them to have the problem. Perhaps my compile on VS 2015 (for some reason) doesn't have the issue? All mine are Win-10/64 Pro. Oh, well! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP 4.2.8p10 released
On 27/03/2017 15:50, Martin Burnicki wrote: [] This is a bug which made it into ntpd 4.2.8p10. I've just found the reason and opened an issue on bugzilla: http://bugs.ntp.org/show_bug.cgi?id=3402 I've also already a fix for this. The best solution for you is to specify the DLL name in a registry key instead of the environment variable. Run regedit and open this registry path: HKLM\System\CurrentControlSet\services\NTP Then create a new key as multipart string, with the name "PPSProviders", and the contents "loopback_pps_api_provider.dll". Or, as a temporary workaround for the environment variables, you could try to append a dummy DLL name to the real DLL name, e.g.: PPSAPI_DLLS=loopback_pps_api_provider.dll;dummy Martin As it happens, on two Win-10/64 Pro PCs here the bug doesn't appear to exist, and they (continue) to run correctly with: PPSAPI_DLLS=loopback-ppsapi-provider.dll I've updated the bug. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP 4.2.8p10 released
On 25/03/2017 22:09, Dan Gearty wrote: I have been using the loopback driver on Windows 10. It had been running OK in older versions up to 4.2.8p9. Now in 4.2.8p10 it appears that junk characters are appended to the driver name when it is called. The junk characters are different each time NTP is restarted. 25 Mar 16:57:32 ntpd[14436]: load_pps_provider: 'C:\Program Files (x86)\NTP\bin\loopback-ppsapi-provider.dll???nY?': The specified module could not be found 25 Mar 16:57:32 ntpd[14436]: time_pps_create: load failed (C:\Program Files (x86)\NTP\bin\loopback-ppsapi-provider.dll???nY?) --> 2 / No such file or directory 25 Mar 16:57:32 ntpd[14436]: load_pps_provider: 'C:\Program Files (x86)\NTP\bin\??h?l?': The specified module could not be found 25 Mar 16:57:32 ntpd[14436]: time_pps_create: load failed (C:\Program Files (x86)\NTP\bin\??h?l?) --> 2 / No such file or directory 25 Mar 16:57:32 ntpd[14436]: load_pps_provider: 'C:\Program Files (x86)\NTP\bin\A': The specified module could not be found 25 Mar 16:57:32 ntpd[14436]: time_pps_create: load failed (C:\Program Files (x86)\NTP\bin\A) --> 2 / No such file or directory 25 Mar 16:57:32 ntpd[14436]: time_pps_create: no providers available 25 Mar 16:57:32 ntpd[14436]: refclock_ppsapi: time_pps_create: Exec format error 25 Mar 16:57:32 ntpd[14436]: GPS_NMEA(4) flag1 1 but PPSAPI fails Dan, Sorry to hear of the problem. PCs Harstad and Lund here are using the loopback DLL and are still working correctly: http://www.satsignal.eu/mrtg/harstad_ntp_2.html http://www.satsignal.eu/mrtg/lund-ntp-2.html Note that I install NTP outside the "Program Files" tree to avoid permissions issues, and most likely I have /not/ updated the loopback DLL. The NTP executables are from my own build: http://www.satsignal.eu/ntp/x86/index.html and checking...the loopback DLL details are: 18/06/2016 15:5175,776 loopback-ppsapi-provider.dll installed in C:\Tools\NTP\bin\ in each case. So that DLL version /does/ work with 4.2.8p10 binaries. Checked on Win-10/64 in each case. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] NTP 4.2.8p10 released
NTP 4.2.8p10 released Windows binaries working on Windows-XP SP3 & later - download: http://www.satsignal.eu/ntp/x86/index.html Source: http://archive.ntp.org/ntp4/ntp-4.2/ntp-4.2.8p10.tar.gz -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] How common is LI=3 - solved.
On 05/02/2017 00:22, Robert Scott wrote: [] By the way, the code I am writing is not part of a NTP algorithm to adjust a system clock for time. It is for a one-time frequency calibration of an oscillator. I take a time snapshot at the beginning and at the end of an approximately six hour period during which I am counting cycles from the oscillator in question. I hope to achieve a frequency accuracy of 5 PPM. Once that measurement is made, I store it for subsequent use in my app. Unless the hardware changes, there is no need to do the calibration again. -Robert Scott Hopkins, MN Robert, I appreciate it's a one-time calibration, but if anyone needs a stable, adjustable frequency source, they might look at the GPS disciplined device: http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=234 -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Time syncing with something other than ntpd
On 03/02/2017 07:42, sean wrote: [] Just curious, any experience with those? [] I'm running a couple of Sure boards here one feeding one PC and the other feeding two PCs in parallel (only one PC has TX connected). No problems. I'm on the top storey of a two storey building, and both devices are using indoor puck antennas. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Time syncing with something other than ntpd
On 02/02/2017 04:34, sean wrote: [] Incidentally I do have a BBB and a few raspberry pis. The BBB goes back and forth to/from work so I won't be able to use that as the NTP host. As an aside, have you done anything with SDR? You may be interested in this: https://github.com/flightaware/piaware Do lets us know how you get on with NTP. Yes, I've done some ADS-B stuff, although using others' code as I don't do "C" myself. For multilateration we need times to better than a microsecond (and ideally to within 100 ns) and this is achieved within the software by comparing several aircraft which are mutually visible between multiple stations, and for some of which GPS locations are known. http://www.satsignal.eu/raspberry-pi/dump1090.html and, of course, I monitor the performance where I can, comparing different systems: http://www.satsignal.eu/mrtg/performance_ads-b.php I've also just started with earthquake detection, something which requires good time keeping (perhaps to within a second!) and may be of interest to west coast USA members: https://www.raspberrypi.org/blog/raspberry-shake-personal-seismograph/ -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Time syncing with something other than ntpd
On 01/02/2017 10:59, Jakob Bohm wrote: [] As I am looking at the BBB myself, here are some extra questions: 1. Do you know if anyone has tried using the real-time coprocessors on the BBB to more accurately track the PPS signal? 2. I presume the BBB could be put in a shielded case (I see some offered online). Any experience with that? Enjoy Jakob Jakob, (1) No. Do you mean using the counters to record the timing of the PPS more precisely? (2) No, but without the BBB radiates more interference than the RPi. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Time syncing with something other than ntpd
On 01/02/2017 05:55, sean wrote: [] Hi Dave, Thank you for the reply. I found your website about 3 weeks ago and got the urge to checkout GPS devices, like the GPS18, Raspberry pi options, etc. Thank you for it and all of the graphs. You certainly have many Pis keep track of the time! I don't recall, are you apart of the NTP Pool? I found your website to have a wealth of great information that's quite well compiled and thoughout. I hope your health is much better this year and that you're on the road to recovery. Primarily I run FreeBSD and was surprised to learn that it can have better precision than Linux, although the articles I read were FreeBSD 8.0 era. Do you find FreeBSD generic kernel comparable with Linux? From what it sounds like, a Raspberry Pi with the device below will give me "pretty accurate" (my words) time, which I can use to sync my devices in my home. http://www.satsignal.eu/mrtg/performance_ntp.php For the Raspberry Pi: https://store.uputronics.com/index.php?route=product/product&product_id=81 That's pretty well priced, cheaper than the Garmin In terms of installations, I think that NTP will have by far the greatest number, and of the three you listed, only NTP runs on Windows. Well I don't really have any Windows installations, but I will keep NTP in mind when I want to run time syncing on Windows. As an aside, what does Windows natively use to keep time and sync? Thanks, Sean Sean, Thanks for your comments - much of the Web site is comprised of my own notes to remind me what to do next time! Still waiting for one minor operation, and then to see if (or should it be when?) the Crohn's returns. Unfortunately I can't be part of the pool as my ISP doesn't offer static addresses. I don't know whether FreeBSD is better than Linux any more, others will need to answer that. My FreeBSD box refused to update from FreeBSD 7 to FreeBSD 8, so I stuck Linux on it in desperation! Another low-cost device is the Sure evaluation board: http://www.satsignal.eu/ntp/Sure-GPS.htm http://www.ebay.com/itm/SKG16A-Bluetooth-RS232-USB-UART-GPS-Module-Demo-Board-/230844194302 Windows uses NTP but not with the reference implementation, so of unknown quality, and not manageable in the same way. It used to be lousy, and I've not tested since then. What will be good enough depends on your needs. The lowest cost might be the Sure board attached to an existing FreeBSD box, running 24 x 7 and in as stable a thermal environment as necessary. Both the Raspberry Pi and BeagleBone Black are low-power devices and therefore low-cost to run 24 x 7, with the BBB having a slightly better Ethernet implementation if you need to get down to the tens of microseconds level, but with the Raspberry Pi have a much wider support even though it might offer (approx) fifties of microseconds. Judge for yourself here: http://www.satsignal.eu/ntp/BBB-vs-RPi.html If you already have an RPi doing something, adding a NTP server to its tasks will make little extra load for an environment with a thousand or more clients -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Help with RESTRICT
On 31/01/2017 23:35, Phil Lee wrote: [] That would be correct IF your LAN is on 192.168.0.n The zero should be replaced with whichever of the /24 subnets under 192.168 is relevant for the actual LAN address scheme. Some DHCP servers on routers default to 192.168.1.n, for example. [] Well, of course! I only showed that as a working example. I hope the address specification issues of the OP can be resolved. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Help with RESTRICT
On 30/01/2017 20:14, Antonio Marcheselli wrote: Hello all [First, I am using google groups, in the past I was told it was causing hassle in terms of formatting but BT have discontinued their news server and I am unable to find an alternative - apologies if these messages are not properly formatted.] I am looking for some advice on the RESTRICT parameter. My configuration file has the following line in it: restrict 172.20.0.0 mask 255.255.0.0 notrust noquery nomodify nokod With the above, a server on 172.20.21.11 was unable to poll the time. I checked on a working configuration and found the below restrict 172.20.0.0/16 mask 255.255.0.0 notrust noquery nomodify nokod but I am concerned that the /16 bit is simply making the whole line void which would explain why it's then working. Basically, I need the 'nokod'. For umpteen reasons, I want the NTP server to never ban any client on the LAN. But I thought that a little restriction would be good practice too. Could you please tell me if the /16 is indeed required or whether I have just made the whole line void? Thanks for your help! Antonio, For a free text-only news server, try Eternal September: https://www.eternal-september.org/ although it seems its security certificate might not be correct. I'm confused by NTP's restrict lines, but I was advised that these allow LAN-only access: # Suggestions for NTP restrictions (accepting ntpq commands from the LAN): restrict source notrap nomodify nopeer restrict 127.0.0.1 restrict ::1 restrict 192.168.0.0 mask 255.255.255.0 Perhaps that helps? -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Time syncing with something other than ntpd
On 30/01/2017 04:13, sean wrote: Hi All, I'm real interested in NTP and accurate time, hence why I'm on this newsgroup. I would like to look into getting a time sensor and I hear the Garmin GPS 18X is what some folks run unless they need much more precision. Is this still a pretty well regarding GPS unit for pretty accurate (I know that's highly subjective) time keeping? This would be a hobbyist thing and I'm not running an important business, if you were going to ask. Next question...Do most folks here use the NTPD client, or it is a mixture of Chrony and openNTPD? Maybe some folks just go with what ships with their OS? The comparison chart is pretty nice and lays each option out nicely: https://chrony.tuxfamily.org/comparison.html I think that's all for now. Feel free to provide any URLs to any resources I should check out about time sycing, NTP, etc. Sean, I have been running NTP on multiple systems since 2002, including Linux and Windows (2000 and later), both with hardware sync (GPS18, GPS18x and multiple GPS devices for the Raspberry Pi), and with LAN and Wi-Fi network sources. I find NTP easy to manage and monitor over multiple systems, and the fact that it runs on Windows, and can accept GPS devices on Windows very valuable. You can easily get within 10 microseconds in Linux (but be careful of the temperature and GPS antenna location), and within 200 microseconds on Windows when using an attached GPS/PPS device. http://www.satsignal.eu/mrtg/performance_ntp.php For the Raspberry Pi: https://store.uputronics.com/index.php?route=product/product&product_id=81 In terms of installations, I think that NTP will have by far the greatest number, and of the three you listed, only NTP runs on Windows. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Optimising NTP build for Raspberry Pi 2
On 07/03/2015 12:41, Neil Green wrote: In an attempt to squeeze all I can out of a NTP and GPS/PPS setup on the Raspberry Pi 2 I’m starting to experiment with compile flags using GCC 4.8. Currently I have: CC="gcc-4.8" CFLAGS="-mcpu=cortex-a7 -mfpu=neon-vfpv4" ./configure --enable-NMEA --enable-ATOM --enable-linuxcaps --disable-all-clocks --disable-parse-clocks --disable-ipv6 Will attempting to optimise the build like this have any positive impact on NTP in terms of precision, stability etc, or am I focussing on an area that will have no benefit? Thanks, Neil. == Neil, From my limited experience, improving stability etc. is best done by tuning the NTP parameters, keeping the temperature as constant as possible, and if you have a PPS source disabling the tickless mode in the kernel. If you are compiling a lot, "make -j5" speeds things up. "--enable-linuxcaps" appear to be unnecessary, and I've not done any comparisons by enabling or disabling different clocks, but anything to reduce the ./configure time would be extremely welcome. I would be most interested to hear of your results. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Writing the drift file
On 07/03/2015 11:12, Harlan Stenn wrote: OK, a fair amount of good stuff is being discussed. Do we mostly all agree that the purpose of the drift file is to give ntpd a hint as to the frequency drift at startup? If so... The current mechanism is designed to handle the case where ntpd is restarted fairly quickly, so there's a good chance the same drift value will work. The reason for this is to get faster startup times. If the value in the drift file is "close enough" and the system is using iburst, ntpd will synch the clock and be ready to go in about 11 seconds' time. Otherwise it can take 5 minutes or more. If conditions are such that the value in the drift file is not "close enough" to the correct value then we're looking at needing 5 minutes or more to get the clock sync'd. How much effort should we go thru to handle some of these situations? I'm inclined to say "not a lot". I mean: (a) there's likely to be something writing far more than a few bytes every hour, and (b) what write rate is or is not acceptable in any case? I see the life of SSD cells quotes in the region on hundreds of thousands, and that's something like 11 years at one write per hour (if my maths is correct). But SSDs and other devices take great pains /not/ to write to a single cell repeatedly, so the life at a few bytes an hour is likely to be grossly in excess of 11 years. Perhaps an option /only/ to write when NTP is closed normally may be worth adding, in addition to the "only write if drift is significantly different". Two user-tunable options: write-only-if-different, write-only-on-shutdown. But as it is I think is quite reasonable. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] moving from ntpdc to ntpq
On 07/03/2015 08:35, catherine.wei1...@gmail.com wrote: [] Hi,Dayvid, just like you said, we're offering ntpq to our customers to test the ntp function, for example, they have sevral ntp servers and need to choose which servers are good, they need to switch between these servers. Thank you. OK, thanks. But it seems strange to me that you are trying to do "by hand" what NTP does quite well by itself, especially if you set up a few "pool" type servers. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Writing the drift file
On 06/03/2015 09:35, Harlan Stenn wrote: Folks, A while ago we got a request from the embedded folks asking for a way to limit the writing of the drift file unless there was a "big enough" change in the value to warrant this. Somebody came up with an interesting way to do this that involves looking to see how much the drift value has changed and only writing the value if the change was "big enough". By my read of the code and the comments: 1) it looks like the code is implementing something other than what the comments want, and 2) what's described *or* implemented seems way more complicated than what we need. I'm wondering if we should just let folks specify a drift/wander threshold, and if the current value is more than that amount we write the file, and if the current value is less than that amount we don't bother updating the file. If folks are on a filesystem where the number of writes doesn't matter, no value would be set (or we could use 0.0) and it's not an issue. Thoughts? Sounds good to me. But do you really mean "current value" or "difference from last written value"? -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] moving from ntpdc to ntpq
On 02/03/2015 09:30, catherine.wei1...@gmail.com wrote: Hi,David, In our system, we need to unconfig and restrict in some operations through ntpq utility which originally was realized by ntpdc. However, ntpdc doesn't work now. In other words, we need to find an equivalent of ntpdc to unconfig, restrict . I found that the ntpq commands are not complete in related documents. Best Regards. Catherine, Yes, I appreciate what you are trying to do, I was asking "why" since it seems a rather unusual requirement. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] moving from ntpdc to ntpq
On 28/02/2015 01:17, catherine.wei1...@gmail.com wrote: [] Hi, Harlan In my system, ntpdc was used to add an ntp server and the command is like this: ntpdc -c "keyid 0" -c addserver 10.172.161.16 minpoll 3 maxpoll 4 burst since keyid is 0, we don't need authentication. But now, I use ntpq to replace ntpdc, if I add :config before "addserver", I need to authenticate. Is there any way to avoid authenticate in ntpq utility? Thank you. I don't know how to addserver in ntpq. There's little knowledge about this on the Internet. Thank you so much. Catherine, Could you remind me again why you need to add and remove servers rather than letting NTP get on with the job? The pool directive allows NTP to add an discard servers as it needs, with NTP monitoring each server's performance. Could that be an alternative approach? If you are in a test environment, what's wrong with simply editing ntp.conf and restarting? -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Type 28 driver (gpsd, SHM) - understanding "flag1"
On 21/02/2015 19:00, Harlan Stenn wrote: David Taylor writes: [] http://www.satsignal.eu/ntp/Raspberry-Pi-quickstart.html http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html Yes, that is appropriate material for the site. There are already pages for how to build for certain other platforms, and there is some fairly specific information about both hardware, BIOS, and software issues for some very specific platforms. Adding to that list on the support.ntp.org site *really* helps because it gets people to look there first, and when they see that the content has been added or improved by others they feel more comfortable adding or improving content themselves. Of course I do not actually *know* how other folks feel in this regard - it's my belief. I can add a pointer to your site if you would like to suggest a suitable starting page. The easy solution would be links to: - www.ntp.org The NTP Project Site - support.ntp.org The NTP Suppport Project - nwtime.org/why-join Become a supporting member of Network Time Foundation - nwtime.org/donate Donations to Network Time Foundation - www.nwtime.orgThe NTF main site We're happy to help in this area and recognize the efforts of folks and sites that help NTF be a success. Thanks for that Harlan. I've added those links to both my Raspberry Pi and Windows setup pages, so I hope that will help. I'm not going to copy the material I already have to the NTP support site, as copies always get out of date and not updated when the master is updated, but if someone wants to add links pointing to my pages they are very welcome. Anyone doing that might include the Windows how-to at: http://www.satsignal.eu/ntp/setup.html -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] chrony as a server
On 21/02/2015 17:52, William Unruh wrote: [] It will do that too. The crucial item there is "the only method of time correction is manual entry" which is different from ntpd and orphan mode. I have no idea why this conversation is continuing. The two are different. The two methods are trying to solve the same problem (timekeeping of isolated systems) but doing so in a different manner. If you like one better than the other, that is fine. But they are not the same. Bill, please enlighten me why I cannot, using NTP's orphan mode, set the time on one PC manually and have another PC sync to it? If you are saying that Chrony cannot work on isolated networks /without/ using manual time entry, I would consider that a significant disadvantage. I'm sure that isn't the case. I thought I might learn something about orphan mode from the discussion, as it's not something I have used or had the need for here. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Type 28 driver (gpsd, SHM) - understanding "flag1"
On 21/02/2015 11:40, Harlan Stenn wrote: David Taylor writes: Thanks, Mike. We are carrying out some tests, but it means leaving the computer down for at least several hours, and we've been trying about 24 hours down so far, so progress isn't rapid! If flag1 allows off-the-network operation after several days outage, that will be fine, but I will have to document it on my Web page. Again, making corrections like this only on your web pages is counter-productive. It *hurts* NTP when incorrect information on the wiki or in the docs is not corrected. It *hurts* NTP when you take eyeballs away from our site, as we need all the help we can get to motivate folks to join or donate. I think there's a misunderstanding here! I am not saying that the information is incorrect, simply that I did not understand it. Until further tests are completed (by someone else), I will not know whether the extra flag is useful in our circumstances. Do you consider "How to make an NTP server with a Raspberry Pi" to be appropriate material for your site? It's the first I've heard of it, if so. These are the two pages which I hope to update: http://www.satsignal.eu/ntp/Raspberry-Pi-quickstart.html http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html I can add a pointer to your site if you would like to suggest a suitable starting page. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Type 28 driver (gpsd, SHM) - understanding "flag1"
On 21/02/2015 08:33, Mike Cook wrote: [] My aged understanding concurs with yours. Set flag 1. Maybe not your desired behavior, but possibly that of the designer. [] Thanks, Mike. We are carrying out some tests, but it means leaving the computer down for at least several hours, and we've been trying about 24 hours down so far, so progress isn't rapid! If flag1 allows off-the-network operation after several days outage, that will be fine, but I will have to document it on my Web page. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Type 28 driver (gpsd, SHM) - understanding "flag1"
Folks, I'm looking at: http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver28.html and wanting to be sure that I understand flag1 correctly. The situation is starting a computer which has no real-time clock, and has been down for a day. This computer is in the middle of nowhere, and has a GPS and PPS as reference clocks, using the type 22 and type 28 drivers. By observation, the type 22 (PPS) driver won't kick in until the type 28 (SHM/gpsd) driver is valid, but also by observation with no flags set it seems that the type 28 driver never syncs at all, even though valid GPS data is present. My reading of that page is: - the default, flag1 = 0 or absent, and no time2 set, NTP will not kick in unless the local clock is within 4 hours of the GPS time. It seems that even with -g as an ntpd parameter, which /should/ allow a large initial offset NTP won't kick in. In the computer in question, the difference is likely to be in excess of 24 hours, so NTP will not attempt to correct the clock. This is not the desired behaviour! Is my understanding correct? Would the correct thing to do in such circumstances be to set flag1 = 1 so that the difference limit is ignored? I ask what may be an obvious question as I appear to have difficulty in reading the page. Perhaps old age, I hope nothing more! I suppose I had expect the "-g" to override other sanity checks. -- Thanks, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] chrony as a server
On 21/02/2015 07:04, William Unruh wrote: [] orphan mode is about a group of computers. "Orphan Mode allows a group of ntpd processes to automonously select a leader in the event that all real time sources become unreachable (i.e. are inaccessible)." chrony's is that you can enter the time by hand (Ie, by typing a current time and hitting enter) on a single machine. You are the "remote clock". Now, how useful that is now adays is open to question, but in the past with telephone modems and flaky connections it was worth something. And if you are setting up something on the Hebrides or on a buoy in the Atlantic where no connection of anykind is possible, it could be useful. Ie, it IS different from orphan mode. "Things chronyd can do that ntpd can?t: chronyd provides support for isolated networks whether the only method of time correction is manual entry (e.g. by the administrator looking at a clock)." The claim is for "networks", not single machines. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] chrony as a server
On 20/02/2015 20:22, William Unruh wrote: [] No. The local clock simply trusts the time (Ie all offsets are defined to be zero) chrony takes the time as entered by hand by the operator and uses that to determine the offset. Of course that will not be terribly accurate ( a second is probably good), but if you are disconnected for a month, a second is probably pretty good accuracy. In practice, how does that differ from orphan mode? I think that statement on behalf of chrony needs to be clarified as it may be misleading. -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] chrony as a server
On 19/02/2015 18:09, Paul wrote: On Thu, Feb 19, 2015 at 12:35 PM, David Taylor < david-tay...@blueyonder.co.uk.invalid> wrote: Accurate and current documentation is both essential and invaluable for any project! Well then under no circumstances should you read the ntp faq/howto at < http://www.ntp.org/ntpfaq/NTP-a-faq.htm>. Yes, what with me also knowing very little Linux, I ended up writing my own "as built" rather than "as designed" guides, such as: http://www.satsignal.eu/ntp/Raspberry-Pi-quickstart.html http://www.satsignal.eu/ntp/setup.html with much help from the folk here! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] chrony as a server
On 19/02/2015 14:20, Paul wrote: On Thu, Feb 19, 2015 at 5:34 AM, David Taylor < david-tay...@blueyonder.co.uk.invalid> wrote: Does not NTP's orphan mode and local clock driver provide this? Refclock 1 (LOCAL/LOCL) is deprecated and I believe as of a recent release it's useless* but "Orphan mode is intended to replace the local clock driver. It provides a single simulated UTC source ...". Note that I provided a link not any commentary on the correctness of the claims at that link. It would be nice if the Chrony docs told the truth but likewise the NTP docs. *Previously LOCL+PPS was a useful configuration, now you need (or should) use kernel PPS. Thanks for the update, Paul. It's something I've never used so please excuse me for confusing the two, and not being quite up-to-date with this. Accurate and current documentation is both essential and invaluable for any project! -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] chrony as a server
On 19/02/2015 01:24, Paul wrote: [] Chrony (in general) pros and cons: < http://chrony.tuxfamily.org/manual.html#Other-time-synchronisation-packages> [] ... whwre it says: "Things chronyd can do that ntpd can’t: chronyd provides support for isolated networks whether the only method of time correction is manual entry (e.g. by the administrator looking at a clock)." Does not NTP's orphan mode and local clock driver provide this? -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
