Re: [ntp:questions] ntpd goes into oscillation
unruh un...@wormhole.physics.ubc.ca wrote in message news:slrnhjkta6.4e4.un...@wormhole.physics.ubc.ca... ntpd has suddenly broken out into oscillations. it is fed by a Garmin 18 LVC PPS via shm. The oscillation has a period of just under an hour ( about 50 min) and an amplitude of about 10usec. in the offsets ( amplitude of about .005PPM in the rate). Since this is acting as the clock for a number of other machines, they are also showing the oscillation especially in the rate. While I suppose this could be something in the GPS itself, it looks more like an oscillation in ntpd. Nothing changed when the oscillations started. Ntpd had been started on Dec 14, and this change began on Dec24. You can see the graph on www.theory.physics.ubc.ca/chrony/chrony.html , the graph for the machine called string. Has anyone else ever seen this kind of thing? Something similar, perhaps, yes, and I reported it here before. It seems that NTP hits the +/- 500 ppm drift limit and can't recover - check the drift file contents. You might try deleting (or renaming) the drift file. I haven't seen this for some time, though. What version are you running? Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ntpd goes into oscillation
In article slrnhjkta6.4e4.un...@wormhole.physics.ubc.ca, unruh un...@wormhole.physics.ubc.ca writes: ntpd has suddenly broken out into oscillations. it is fed by a Garmin 18 LVC PPS via shm. The oscillation has a period of just under an hour ( about 50 min) and an amplitude of about 10usec. in the offsets ( amplitude of about .005PPM in the rate). Since this is acting as the clock for a number of other machines, they are also showing the oscillation especially in the rate. While I suppose this could be something in the GPS itself, it looks more like an oscillation in ntpd. Nothing changed when the oscillations started. Ntpd had been started on Dec 14, and this change began on Dec24. You can see the graph on www.theory.physics.ubc.ca/chrony/chrony.html , the graph for the machine called string. Has anyone else ever seen this kind of thing? What OS? (version?) What is the temperature like? If you feed a sawtooth into a PLL, the offset will be the derivative, a square wave. The amplitude of the square wave is smaller with higher gain. A sawtooth with a 1 hour period is possible from air conditioners. I've seen oscillations on boxes using the pool, or at least stuff that looks like oscillations to my eyeball. That's on Linux. (They have been fixing the timekeeping code. I wouldn't be surprised by anything.) -- These are my opinions, not necessarily my employer's. I hate spam. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] A faster settling NTP
On 2009-12-27, Danny Mayer ma...@ntp.org wrote: unruh wrote: The problem with the current ntpd license is that it is a combination of a copyright claim, and a license. Thus the writers cannot simply state that they are using the general license, since it also makes a copyright claim. (It also confusingly refers to the U Delaware when the copyright holder is D Mills). Dave Mills transferred the license and copyright and ownership to University of Delaware some time ago. The notice reflects that transfer. The notice in 4.2.4p4, which is the version I have, says that David Mills owns the copyright. Copyright (c) David L. Mills 1992-2007 Looking at the Developement branch, the copyright notice now says that U Delaware owns the copyright, as you say, and lists a series of authors of the work. This document is still confusing since it is still a combination of copyright claim and license. Another author cannot use it, since he owns the copyright to his own work, not the U Delaware, unless he transfers his copyright to the U Delaware. Such a transfer cannot be implicit, and it certainly cannot be claimed that this license and copyright ownership applies simply because the authors removed all copyright and license text from their contribution. While the chances of those authors making a copyright claim against a big user are slim, a big company has to protect itself (the big pockets theory of US law suits make them easy targets). I guess if one of the authors did sue the big company, it could turn around and sue U Delaware for falsely stating it owned the copyright and claiming it had the right to issue a license. Danny ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ntpd goes into oscillation
On 2009-12-30, David J Taylor david-tay...@blueyonder.delete-this-bit.and-this-part.co.uk.invalid wrote: unruh un...@wormhole.physics.ubc.ca wrote in message news:slrnhjkta6.4e4.un...@wormhole.physics.ubc.ca... ntpd has suddenly broken out into oscillations. it is fed by a Garmin 18 LVC PPS via shm. The oscillation has a period of just under an hour ( about 50 min) and an amplitude of about 10usec. in the offsets ( amplitude of about .005PPM in the rate). Since this is acting as the clock for a number of other machines, they are also showing the oscillation especially in the rate. While I suppose this could be something in the GPS itself, it looks more like an oscillation in ntpd. Nothing changed when the oscillations started. Ntpd had been started on Dec 14, and this change began on Dec24. You can see the graph on www.theory.physics.ubc.ca/chrony/chrony.html , the graph for the machine called string. Has anyone else ever seen this kind of thing? Something similar, perhaps, yes, and I reported it here before. It seems that NTP hits the +/- 500 ppm drift limit and can't recover - check the drift file contents. You might try deleting (or renaming) the drift file. I haven't seen this for some time, though. What version are you running? Nope, the drift is NOT at the limit ( it is at about 200) ntp 2.4.2p4 Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ntpd goes into oscillation
On 2009-12-30, Hal Murray hal-use...@ip-64-139-1-69.sjc.megapath.net wrote: In article slrnhjkta6.4e4.un...@wormhole.physics.ubc.ca, unruh un...@wormhole.physics.ubc.ca writes: ntpd has suddenly broken out into oscillations. it is fed by a Garmin 18 LVC PPS via shm. The oscillation has a period of just under an hour ( about 50 min) and an amplitude of about 10usec. in the offsets ( amplitude of about .005PPM in the rate). Since this is acting as the clock for a number of other machines, they are also showing the oscillation especially in the rate. While I suppose this could be something in the GPS itself, it looks more like an oscillation in ntpd. Nothing changed when the oscillations started. Ntpd had been started on Dec 14, and this change began on Dec24. You can see the graph on www.theory.physics.ubc.ca/chrony/chrony.html , the graph for the machine called string. Has anyone else ever seen this kind of thing? What OS? (version?) Linux-- Mandriva 2008.1 ( kernel 2.6.24.7-desktop-3mnb) This oscillation has just started. What is the temperature like? The temp should be relatively stable ( certainly no air conditioner, although possibly cooler than usual because the heating has been turned down for the Christmas break-- After all nothing happens in the University during Christmas. Research-- what's that?. HOwever it so happens that I have the internal temp recorded via lmsensors for the past 5 days, and there is some evidence of a one degree flucutation (the resolution of the onboard thermometers) with about the same period. No idea what that is, since there is no airconditioning/heating. But I suppose it could be causing that fluctuation in the rate and thus the offset. Which somehow started on Dec 24. Lets see what happens when classes begin again next week. If you feed a sawtooth into a PLL, the offset will be the derivative, a square wave. The amplitude of the square wave is smaller with higher gain. A sawtooth with a 1 hour period is possible from air conditioners. Actually, no, the offset is the integral, not the derivative, of the drift, so the offset will be a bunch of peaks. I've seen oscillations on boxes using the pool, or at least stuff that looks like oscillations to my eyeball. That's on Linux. (They have been fixing the timekeeping code. I wouldn't be surprised by anything.) Yes, but then this fix whatever it is, has been the same for months now. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] How to debug GPS PPS?
On Dec 28, 7:59 am, Thomas Laus lau...@acm.org wrote: On 2009-12-28, xyz-2041 xyz2...@gmail.com wrote: Plugged in the GPS unit's serial cable into a Windows computer running WinOncore12 v1.0 (Build 37): http://www.google.com/#q=WinOncore12Installation.exe Seemed to work without any problems. Generated all sort of graphs and charts. Let it run and it told me exact latitude, longitude and height above sea level. Used an analog volt meter and from pin 5 (supposed to be ground), I only noticed voltage on pins 2 and 3. Pin 2 was going erratically negative once a second. I believe that this must be received data as per standards. Pin 3 was +5 volts, but dropping to -5 volts once per second. You did not mention how your Oncore receiver was being interfaced to your computer or it's model number. GT+. Serial port. I use one of the TAPR boards and Oncore UT+ combination. The NTP refclock driver for the Oncore includes the code for receiving the PPS signal on the computer DCD pin. It doesn't need pulse stretching? I've changed my configs a bit, /var/log/ntp.log and /var/log/ntpd.log don't show any errors. However, ntpq -c pe still doesn't show any response: GPS_NMEA(0) .GPS. 0 l - 16 0 0.000 0.000 0.001 PPS(0) .GPS. 0 l - 16 0 0.000 0.000 0.001 GPS_ONCORE(0) .GPS-. 0 l - 16 0 0.000 0.000 0.001 You should not be using GPS_NMEA or PPS. OK. Turned both of those off. The type 30 refclock communicates with the receiver using Motorola Binary protocol. You may need to use WinOncore to set your receiver communications to use the binary protocol or even better, reset the receiver to factory defaults. OK. Used WinOncore to default. Made sure that it was set to Motorola/binary. Power cycled. Hooked back up to FreeBSD server. This is what was produced--for a while: remote refid st t when poll reach delay offset jitter == GPS_ONCORE(0) .GPS.0 l 99 16 400.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 200 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 418 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 636 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 938 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 1167 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 1226 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 1352 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 2028 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 61m 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 67m 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 176m 1600.000 192.362 0.002 Re-defaulted. Now back to this: GPS_ONCORE(0) .GPS.0 l- 1600.000 0.000 0.002 Your config files already have your position defined, so there is no need to have anything in your receiver at startup. The almanac will be received while NTP is settling down after startup. You will need to configure at least 4 other NTP servers to speed up the initial startup. Got those. The refclock code wants to have a synchronized NTP server before adding itself to the peer selection. I find about 30 minutes after a cold start my PPS LED will start to flash and I observe that my Oncore gets selected. PPS LED was flashing, but NTP never synchronized. - Create symbolic links: ln -s /dev/cuad0 /dev/oncore.pps.0 ln -s /dev/cuad0 /dev/oncore.serial.0 ln -s /dev/cuad0 /dev/gps0 ln -s /dev/cuad0 /dev/pps0d - Create /etc/devfs.conf links: link cuad0 pps0 link cuad0 gps0 link cuad0 oncore.pps.0 link cuad0 oncore.serial.0 I think that you will find that the symbolic links in /dev are not required and only the /etc/devfs.conf entries are all you will need. You won't need either pps0 or gps0 entries for anything. Only the oncore* stuff is needed for the refclock type 30. OK. Well, this just doesn't seem to be working. Does anyone have other suggestions on how to get this GT+ working? If not, does anyone have some other suggestions? Would I be able to use this Motorola antenna with another GPS unit? Other low-cost ways of getting GPS accuracy on this FreeBSD/NTP box? Tom --- Public Keys: PGP KeyID = 0x5F22FDC1 GnuPG KeyID = 0x620836CF ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] How to debug GPS PPS?
xyz-2041 wrote: On Dec 28, 7:59 am, Thomas Laus lau...@acm.org wrote: On 2009-12-28, xyz-2041 xyz2...@gmail.com wrote: Plugged in the GPS unit's serial cable into a Windows computer running WinOncore12 v1.0 (Build 37): http://www.google.com/#q=WinOncore12Installation.exe Seemed to work without any problems. Generated all sort of graphs and charts. Let it run and it told me exact latitude, longitude and height above sea level. Used an analog volt meter and from pin 5 (supposed to be ground), I only noticed voltage on pins 2 and 3. Pin 2 was going erratically negative once a second. I believe that this must be received data as per standards. Pin 3 was +5 volts, but dropping to -5 volts once per second. You did not mention how your Oncore receiver was being interfaced to your computer or it's model number. GT+. Serial port. I use one of the TAPR boards and Oncore UT+ combination. The NTP refclock driver for the Oncore includes the code for receiving the PPS signal on the computer DCD pin. It doesn't need pulse stretching? I'm not familiar with the oncore but you mentioned checking levels on serial pins but didn't state what you found on pin 1. Can you check this for the pps signal? Try a large setting for mindist. tos mindist 0.05 Also remove any minpoll/maxpoll from your server line or set to minpoll 6. David I've changed my configs a bit, /var/log/ntp.log and /var/log/ntpd.log don't show any errors. However, ntpq -c pe still doesn't show any response: GPS_NMEA(0) .GPS.0 l- 1600.000 0.000 0.001 PPS(0) .GPS.0 l- 1600.000 0.000 0.001 GPS_ONCORE(0) .GPS-. 0 l- 1600.000 0.000 0.001 You should not be using GPS_NMEA or PPS. OK. Turned both of those off. The type 30 refclock communicates with the receiver using Motorola Binary protocol. You may need to use WinOncore to set your receiver communications to use the binary protocol or even better, reset the receiver to factory defaults. OK. Used WinOncore to default. Made sure that it was set to Motorola/binary. Power cycled. Hooked back up to FreeBSD server. This is what was produced--for a while: remote refid st t when poll reach delay offset jitter == GPS_ONCORE(0) .GPS.0 l 99 16 400.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 200 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 418 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 636 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 938 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 1167 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 1226 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 1352 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 2028 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 61m 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 67m 1600.000 192.362 0.002 GPS_ONCORE(0) .GPS.0 l 176m 1600.000 192.362 0.002 Re-defaulted. Now back to this: GPS_ONCORE(0) .GPS.0 l- 1600.000 0.000 0.002 Your config files already have your position defined, so there is no need to have anything in your receiver at startup. The almanac will be received while NTP is settling down after startup. You will need to configure at least 4 other NTP servers to speed up the initial startup. Got those. The refclock code wants to have a synchronized NTP server before adding itself to the peer selection. I find about 30 minutes after a cold start my PPS LED will start to flash and I observe that my Oncore gets selected. PPS LED was flashing, but NTP never synchronized. - Create symbolic links: ln -s /dev/cuad0 /dev/oncore.pps.0 ln -s /dev/cuad0 /dev/oncore.serial.0 ln -s /dev/cuad0 /dev/gps0 ln -s /dev/cuad0 /dev/pps0d - Create /etc/devfs.conf links: link cuad0 pps0 link cuad0 gps0 link cuad0 oncore.pps.0 link cuad0 oncore.serial.0 I think that you will find that the symbolic links in /dev are not required and only the /etc/devfs.conf entries are all you will need. You won't need either pps0 or gps0 entries for anything. Only the oncore* stuff is needed for the refclock type 30. OK. Well, this just doesn't seem to be working. Does anyone have other suggestions on how to get this GT+ working? If not, does anyone have some other suggestions? Would I be able to use this Motorola antenna with another GPS unit? Other low-cost ways of getting GPS accuracy on this FreeBSD/NTP box? ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] How to debug GPS PPS?
On 2009-12-30, David Lord sn...@lordynet.org wrote: xyz-2041 wrote: On Dec 28, 7:59 am, Thomas Laus lau...@acm.org wrote: ... If not, does anyone have some other suggestions? Would I be able to use this Motorola antenna with another GPS unit? Other low-cost ways of getting GPS accuracy on this FreeBSD/NTP box? the standard is the Garmin GPS18xLVC unit. Cost about $60, plus some soldering of a serial port and usb port plug(for power) onto the wires. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] How to debug GPS PPS?
unruh wrote: On 2009-12-30, David Lord sn...@lordynet.org wrote: xyz-2041 wrote: On Dec 28, 7:59 am, Thomas Laus lau...@acm.org wrote: ... If not, does anyone have some other suggestions? Would I be able to use this Motorola antenna with another GPS unit? Other low-cost ways of getting GPS accuracy on this FreeBSD/NTP box? the standard is the Garmin GPS18xLVC unit. Cost about $60, plus some soldering of a serial port and usb port plug(for power) onto the wires. Mine was good for 1us during period I had it setup in summer but when I tested more recently PPS was very erratic, I suspect because it's TTL level with borderline pull down when temperature drops (can also see this from MSF receiver also TTL outputs). So depending on serial port of pc it may need PPS signal converting to rs232. David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] How to debug GPS PPS?
xyz-2041 wrote: Plugged in the GPS unit's serial cable into a Windows computer running WinOncore12 v1.0 (Build 37): http://www.google.com/#q=WinOncore12Installation.exe Seemed to work without any problems. Generated all sort of graphs and charts. Let it run and it told me exact latitude, longitude and height above sea level. Used an analog volt meter and from pin 5 (supposed to be ground), I only noticed voltage on pins 2 and 3. Pin 2 was going erratically negative once a second. I believe that this must be received data as per standards. Pin 3 was +5 volts, but dropping to -5 volts once per second. I've changed my configs a bit, /var/log/ntp.log and /var/log/ntpd.log don't show any errors. However, ntpq -c pe still doesn't show any response: GPS_NMEA(0) .GPS.0 l- 1600.000 0.000 0.001 PPS(0) .GPS.0 l- 1600.000 0.000 0.001 GPS_ONCORE(0) .GPS-. 0 l- 1600.000 0.000 0.001 Also: ntpdc -c kerninfo pll offset: -0.00539973 s pll frequency:-46.079 ppm maximum error:0.097522 s estimated error: 0.003708 s status: 2201 pll ppsjitter nano pll time constant:8 precision:1e-09 s frequency tolerance: 496 ppm pps frequency:-9.224 ppm pps stability:0.000 ppm pps jitter: 0 s calibration interval: 4 s calibration cycles: 0 jitter exceeded: 0 stability exceeded: 0 calibration errors: 0 Here is what I have done so far: - Edit new kernel config file: cd /usr/src/sys/i386/conf/ nano PPS-Generic # ~ # Generic kernel configuration with PPS_SYNC option # include GENERIC ident PPS-GENERIC # Enable support for the kernel PLL to use an external PPS signal, # under supervision of [x]ntpd(8) # More info in ftp://ftp.udel.edu/pub/ntp/kernel.tar.Z options PPS_SYNC # ~ - Build and compile the new kernel: cd /usr/src ls -lt /usr/src/sys/i386/conf make buildkernelKERNCONF=PPS-GENERIC This should take 10 mins to 2 hours depending on the speed of your computer. Check to see that it was created: cd /usr/obj/usr/src/sys/PPS-GENERIC ls -lta | more - Install the new kernel: cd /usr/src make installkernel KERNCONF=PPS-GENERIC Check that the new kernel is installed: cd /boot ls -lta These directories should be there: kernel kernel.old Go into each directory and notice the time stamps of the kernel files: cd /boot/kernel ls -lta | grep kernel -r-xr-xr-x 1 root wheel 10204732 Dec 19 13:44 kernel -r-xr-xr-x 1 root wheel 31172114 Dec 19 13:44 kernel.symbols cd /boot/kernel.old ls -lta | grep kernel -r-xr-xr-x 1 root wheel 10201628 May 1 2009 kernel -r-xr-xr-x 1 root wheel 31167198 May 1 2009 kernel.symbols Reboot: shutdown -r now - Check if new kernel running After rebooting and logging in: uname -a | grep PPS You should get a readout of the kernel name which should include PPS - Create Oncore config file cd /etc nano ntp.oncore0 MODE 1 LON -75.7479 LAT 39.6632 HTGPS 67 FT DELAY 30 NS - Create symbolic links: ln -s /dev/cuad0 /dev/oncore.pps.0 ln -s /dev/cuad0 /dev/oncore.serial.0 ln -s /dev/cuad0 /dev/gps0 ln -s /dev/cuad0 /dev/pps0d - Create /etc/devfs.conf links: link cuad0 pps0 link cuad0 gps0 link cuad0 oncore.pps.0 link cuad0 oncore.serial.0 - Check them: ls -lta /dev | more - Edit /etc/ntp.conf: # ~~ # This is the configuration file for NTP # (Network Time Protocol). More info at # www.NTP.org # # /etc/ntp.conf # This computer will act as a stratum 2 time # server, by referencing the following 4 or # more stratum 1 time servers: server ntp2.netwrx1.com iburst # WI server otc1.psu.edu iburst # PA server t2.timegps.netiburst # CA server tick.usask.ca iburst # CAN # GPS NMEA (numbers seconds only) # server 127.127.20.0 prefer minpoll 4 maxpoll 4 server 127.127.20.0 minpoll 4 maxpoll 4 #flag3 Controls the kernel PPS discipline: 0 for disable (default), 1 for enable. # fudge 127.127.20.0 flag3 1 fudge127.127.20.0 flag3 0 # GPS PPS server 127.127.22.0 prefer minpoll 4 maxpoll 4 #flag3 Controls the kernel PPS discipline: 0 for disable (default), 1 for enable. fudge 127.127.22.0 flag3 1 fudge 127.127.22.0 refid GPS # GPS Oncore driver server 127.127.30.0 fudge 127.127.30.0 refid GPS-Oncore # Since the clock on most PCs drifts around # significantly, let's use a file to # keep track of that drift and compensate # for it: driftfile /etc/ntp.drift # This server will broadcast NTP timing signals # over the Local Area Network (LAN):
Re: [ntp:questions] How to debug GPS PPS?
Richard B. Gilbert wrote: Your biggest problem may be that Windows is not exactly the world's greatest time keeper! The clock ticks every 17 milliseconds! Did you mean to write 1ms? I'm not sure if the latest actually go down to 500 microseconds. Still poor compared with the sub-microsecond precision on most recent Unix and Linux systems. However that is all irrelevant as it is quite clear that ntpd is NOT running on Windows in this case! ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
