Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Hi David, OK, you've convinced me. I've put noselect on the GPS and taken it away on the New York NIST server. The NY NIST server is now preferred and polling from 1 - 4 minutes. Hopefully they won't ban me for hitting it too often. I think the NIST server will have more jitter, particularly as the polling interval increases, but we'll see what happens. Sincerely, Ron It will be interesting to see what difference that makes, Ron, and I look forward to seeing the graphs. Personally, I saw little to choose between the various Internet servers you had, and I would have allowed four or five to be selected rather than just one, as that would not then leave NTP open to failure of the one server, and it would allow NTP to select what It believes to be the best. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
unruh un...@invalid.ca wrote in message news:I1T7r.36416$l12.35...@newsfe23.iad... [] Did you shut down and restart your computer? Did you perchance do this during the daylight savings time transition on a Windows system? Could the error be related to the fact that Windows like time on localtime not UTC? Windows uses UTC internally, not local time. Local time is simply a presentation layer issue. Windows is unaffected by a DST transition. David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Offset Average (Normal)?
Alby VA alb...@empire.org wrote in message
news:2ece7b6a-e150-432d-b23a-a4bde46df...@j11g2000yqj.googlegroups.com...
[]
Hm, what do you think about this command for getting
loopstat data?
tail -n1 -r loopstats | awk '{print $3}'
tail -n1 -r loopstats = This looks at the last line of the loopstat
file
awk '{print $3}' === This pulls the data from the 3rd field which is
the offset info
Example:
--
godzilla# tail -n1 -r loopstats | awk '{print $3}'
0.02814
If you could code that into a perl script that MRTG uses, we'd be
golden.
To work over a network, I really need data which is available through the
standard ntpq command. You are welcome to find a Perl expert who could
coude that for your local PC, though.
I will raise a bug report for NTP about the precision of the data being
sometimes now marginal.
Cheers,
David
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Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
On 2012-03-13, Ron Frazier (NTP) timekeepingntpl...@c3energy.com wrote: Hi all, I just woke up to a 50 SECOND clock error. Prior to the error, with my PC locked into the GPS and the internet servers noselected, here's what my peerstats looked like. Baseline is the GPS. Colored lines are internet servers. http://dl.dropbox.com/u/9879631/drifting01-peerstats.20120312.jpg Looking at this graph, I see that the nmea source was already difting before the sudden jump. It lost 30ms wrt the other servers in the 20 hours beforehand. Then it went crazy for a while and jumped to 80 ms ahead. I agree that this does seem to be that gps device. Which one is it? But that jump is 120ms not 50 sec. I recently had a Garmin 18 go nuts-- giving massive amounts of noise. Here is what was showing on the Meinberg Time Server Monitor when I woke up: http://dl.dropbox.com/u/9879631/drifting02a%20-%20insane.jpg And the graph of the peerstats for that time: http://dl.dropbox.com/u/9879631/drifting02b%20-%20peerstats%20insane.jpg The clock error was REAL, as confirmed by my atomic wrist watch. However, the loopstats graph for the same time period shows no problem with the GPS: http://dl.dropbox.com/u/9879631/drifting02c%20-%20gps%20NOT%20insane.jpg So, I shut down NTPD and reset the time with a batch file that calls ntpdate and querys the New York NIST server: http://dl.dropbox.com/u/9879631/drifting02d%20-%20set%20with%20ntpdate.jpg Here is the time server monitor shortly after NTPD restart: http://dl.dropbox.com/u/9879631/drifting02e%20-%20shortly%20after%20ntpd%20restart.jpg And after a 2nd restart: http://dl.dropbox.com/u/9879631/drifting02f%20-%202nd%20ntpd%20restart%20after%20insane.jpg And here are the current peerstats, which look normal. The offset to the internet servers tends to drift and will eventually cross the zero line and get positive. http://dl.dropbox.com/u/9879631/drifting02g%20-%20peerstats%20after%20insane%20and%202nd%20reset.jpg The GPS appears to have been stable all through this, and was never powered off or unplugged. It looks like NTPD went crazy and reset my clock for some reason. It also reset all of the remote servers at the same time? Since it was an offset of your system with respect to the remote systems. Here are the peerstats and loopstats during the insane period. http://dl.dropbox.com/u/9879631/loopstats.20120313-1-restart%20around%201350%20utc http://dl.dropbox.com/u/9879631/peerstats.20120313-1-insane Here is my current ntp.conf: http://dl.dropbox.com/u/9879631/ntp.conf My system is Windows 7, NTP 4.2.7p259, GPS GlobalSat BU-353 USB NMEA only with GPGGA sentence at 57,600 baud. If anyone can shed some light on what happened, please do. It's driving me bonkers. I don't believe the GPS is at fault, and I suspect NTPD. Again, the remote servers all agree. The GPS time does not (driving your system time) . Thanks in advance. Sincerely, Ron ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Ron Frazier (NTP) wrote: On 3/13/2012 5:39 PM, David Lord wrote: Ron Frazier (NTP) wrote: On 3/13/2012 2:40 PM, Chris Albertson wrote: On Tue, Mar 13, 2012 at 9:52 AM, Ron Frazier (NTP) timekeepingntpl...@c3energy.com wrote: Hi all, I just woke up to a 50 SECOND clock error. Prior to the error, with my PC locked into the GPS and the internet servers noselected, here's what my peerstats looked like. Baseline is the GPS. Colored lines are internet servers. http://dl.dropbox.com/u/9879631/drifting01-peerstats.20120312.jpg Looks to me like that GPS, maybe lock lock and was able to coast on hold over for a while then fell off a cliff. If you have a log of satellite signal to noise ratios you might be able to figure out why. The internet servers appear to be 100% reliable seeing as they all agree. These kinds of things are why some hobbysts end up buying multiple GPS (different brands) Otherwise it is hard to sort out a GPS firmware bug from a solar storm or just that there were not sats visable to your indoor antenna for a few minutes I think your goal is to learn about all of this so these problems are a good thing. No one learns much from working systems. But if the goal is a reliable NTP server, the pool NTP servers can't be beat except by a good timing mode GPS, that has good self diagnostics and PPS. The self diagnostics part is important The link you quoted just now is not the one that bugs me so much today. This one is the one that bugs me today, where my clock was stepped by 50 seconds for some reason. http://dl.dropbox.com/u/9879631/drifting02b%20-%20peerstats%20insane.jpg I'm on a text mostly system so why do you require me to use a web browser to help you? What is your current ntp.conf, ntpd version, operating system and response of ntpq -crv -p after ntpd has had at least a day to stabilise? Not so long ago you posted that you had an offset within +/- 6 ms but didn't give any evidence. Response from ntpq -crv -p or better a day from peer_summary or couple of days from loop_summary would be enough. David When I get the Sure board, I plan to hang it on the pc in tandem with this GPS and compare. Sincerely, Ron Hi David L., I just figured the images and dropbox would be the fastest way to distribute the information. I didn't think I could attach files to messages going to the NTP questions mailing list. I'll be glad to provide stats files if anyone is interested. Just tell me how to distribute them. Based on advice from David Taylor, I just changed my configuration. Previously, I had only the GPS selectable and the internet servers noselected for testing purposes to try to determine where a slow drifting behavior is coming from. Now, I have changed that so the GPS is noselected and the New York NIST server is the preferred and only selectable peer. I am monitoring the GPS and other internet servers for comparison. So, it will be a couple of days before this configuration accumulates some stats files. Even though I have been tinkering with this GPS for a couple of months, I have never seen anything like the 50 second jump I started this thread about. That problem may not be reproducible for some time, if at all. Faulty GPS, incorrect configuration, anybodies guess? Internet servers give me an rms offset about 610us, whilst GPS with PPS gives about 4us. There are day to day variations and some rare 'events' when GPS or an internet server goes bad. GPS without PPS, Globalsat BR304, wasn't worth using as ntp source due to large variations in offset from the NMEA sentences that were tried with RMC being best giving 50% of offsets under 10ms but maximum offsets being near 100ms. MSF radioclock mostly has offset below 1500us. DCF radioclock can have offset below 100us but reception is too variable being non existant for some periods each day. I use mrtg to monitor my servers because it's easy to see when a fault occurs but the graphs don't help to locate the cause. (1) Internet servers only, rms offset 609us: loopstats.20120313 loop 71, 368+/-1360.5, rms 608.7, freq 1.24+/-0.173, var 0.112 peerstats.20120313 ident cnt mean rms max delay dist disp == 81.187.61.74 70 -0.1230.5061.2550.416 21.959 10.600 158.152.1.76 690.1180.9272.025 17.864 28.174 10.205 130.88.200.4 706.0991.6863.553 23.694 33.833 10.345 90.155.53.94 68 -0.0341.1272.952 17.376 29.720 10.938 79.135.97.79 710.5730.7221.388 31.522 38.183 10.618 130.159.196.117 750.3130.9671.830 27.958 35.9169.516 (2) GPS with PPS, local and internet servers, rms offset 3.4us: loopstats.20120313 loop 1350, 4+/-25.6, rms 3.4, freq -35.28+/-0.222, var 0.067 peerstats.20120313 ident cnt mean rms max delay
Re: [ntp:questions] Offset Average (Normal)?
On Mar 14, 2:55 am, David J Taylor david-
tay...@blueyonder.co.uk.invalid wrote:
Alby VA alb...@empire.org wrote in message
news:2ece7b6a-e150-432d-b23a-a4bde46df...@j11g2000yqj.googlegroups.com...
[]
Hm, what do you think about this command for getting
loopstat data?
tail -n1 -r loopstats | awk '{print $3}'
tail -n1 -r loopstats = This looks at the last line of the loopstat
file
awk '{print $3}' === This pulls the data from the 3rd field which is
the offset info
Example:
--
godzilla# tail -n1 -r loopstats | awk '{print $3}'
0.02814
If you could code that into a perl script that MRTG uses, we'd be
golden.
To work over a network, I really need data which is available through the
standard ntpq command. You are welcome to find a Perl expert who could
coude that for your local PC, though.
I will raise a bug report for NTP about the precision of the data being
sometimes now marginal.
Cheers,
David
Thanks. That bug report sounds like the best plan of attack.
Can that bug report be tracked to see if any action is taken?
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Re: [ntp:questions] Offset Average (Normal)?
Alby VA alb...@empire.org wrote in message news:0d4f588e-bab6-4706-826e-299149054...@i2g2000vbv.googlegroups.com... [] Thanks. That bug report sounds like the best plan of attack. Can that bug report be tracked to see if any action is taken? Yes, it's number 2164. See: http://bugs.ntp.org/show_bug.cgi?id=2164 Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
On 3/14/2012 2:46 AM, David J Taylor wrote: Hi David, OK, you've convinced me. I've put noselect on the GPS and taken it away on the New York NIST server. The NY NIST server is now preferred and polling from 1 - 4 minutes. Hopefully they won't ban me for hitting it too often. I think the NIST server will have more jitter, particularly as the polling interval increases, but we'll see what happens. Sincerely, Ron It will be interesting to see what difference that makes, Ron, and I look forward to seeing the graphs. Personally, I saw little to choose between the various Internet servers you had, and I would have allowed four or five to be selected rather than just one, as that would not then leave NTP open to failure of the one server, and it would allow NTP to select what It believes to be the best. Cheers, David Hi David, OK. You asked for it. 8-) When I'm through testing, I'll open up the other internet servers as a backup in case the GPS fails. For now, I'm just running with one clock source at a time. Still trying to document and chase down this wandering effect. I ran with NY NIST as the only selectable clock source and monitoring the GPS for comparison all night. The results were horrible. My offsets from NIST time were in the + 65 ms / - 75 ms range. I had the polling interval set to start at 1 minute and go up to 4 minutes. There is way too much clock wander to even think about testing the accuracy of the GPS. I've gone back to polling the GPS every 8 seconds as the sole selectable clock source and monitoring the internet servers for comparison. Over the short term, minutes to hours, my GPS, even with NMEA only, is by far the most accurate time source I have. Even if the NMEA signal wanders 70 ms either way over the course of a few days, it won't get any further off than I did using the internet server, and the clock will be much more consistent over shorter time frames. Here are the graphs. http://dl.dropbox.com/u/9879631/nynist01.jpg http://dl.dropbox.com/u/9879631/nynist02.jpg Sincerely, Ron PS - By the way, I've changed my ntp.conf a few times since I originally started this thread, including the one in dropbox. What's in there now is my current ntp.conf, not the one that was in there when I started the thread. -- (PS - If you email me and don't get a quick response, don't be concerned. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new messages very quickly. If you need a reply and have not heard from me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude AT c3energy.com ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
On 3/14/2012 3:03 AM, unruh wrote: On 2012-03-13, Ron Frazier (NTP)timekeepingntpl...@c3energy.com wrote: Hi all, I just woke up to a 50 SECOND clock error. Prior to the error, with my PC locked into the GPS and the internet servers noselected, here's what my peerstats looked like. Baseline is the GPS. Colored lines are internet servers. http://dl.dropbox.com/u/9879631/drifting01-peerstats.20120312.jpg Looking at this graph, I see that the nmea source was already difting before the sudden jump. It lost 30ms wrt the other servers in the 20 hours beforehand. Then it went crazy for a while and jumped to 80 ms ahead. I agree that this does seem to be that gps device. Which one is it? But that jump is 120ms not 50 sec. I recently had a Garmin 18 go nuts-- giving massive amounts of noise. That's very interesting. David Taylor also said he saw this NMEA wandering effect on the Garmin. Did your Garmin recover? And, is it based on a SIRF chipset? In another thread, someone else with a BU-353 said he saw an offset storm like the one in my graph. Sincerely, Ron Here is what was showing on the Meinberg Time Server Monitor when I woke up: http://dl.dropbox.com/u/9879631/drifting02a%20-%20insane.jpg And the graph of the peerstats for that time: http://dl.dropbox.com/u/9879631/drifting02b%20-%20peerstats%20insane.jpg The clock error was REAL, as confirmed by my atomic wrist watch. However, the loopstats graph for the same time period shows no problem with the GPS: http://dl.dropbox.com/u/9879631/drifting02c%20-%20gps%20NOT%20insane.jpg So, I shut down NTPD and reset the time with a batch file that calls ntpdate and querys the New York NIST server: http://dl.dropbox.com/u/9879631/drifting02d%20-%20set%20with%20ntpdate.jpg Here is the time server monitor shortly after NTPD restart: http://dl.dropbox.com/u/9879631/drifting02e%20-%20shortly%20after%20ntpd%20restart.jpg And after a 2nd restart: http://dl.dropbox.com/u/9879631/drifting02f%20-%202nd%20ntpd%20restart%20after%20insane.jpg And here are the current peerstats, which look normal. The offset to the internet servers tends to drift and will eventually cross the zero line and get positive. http://dl.dropbox.com/u/9879631/drifting02g%20-%20peerstats%20after%20insane%20and%202nd%20reset.jpg The GPS appears to have been stable all through this, and was never powered off or unplugged. It looks like NTPD went crazy and reset my clock for some reason. It also reset all of the remote servers at the same time? Since it was an offset of your system with respect to the remote systems. Here are the peerstats and loopstats during the insane period. http://dl.dropbox.com/u/9879631/loopstats.20120313-1-restart%20around%201350%20utc http://dl.dropbox.com/u/9879631/peerstats.20120313-1-insane Here is my current ntp.conf: http://dl.dropbox.com/u/9879631/ntp.conf My system is Windows 7, NTP 4.2.7p259, GPS GlobalSat BU-353 USB NMEA only with GPGGA sentence at 57,600 baud. If anyone can shed some light on what happened, please do. It's driving me bonkers. I don't believe the GPS is at fault, and I suspect NTPD. Again, the remote servers all agree. The GPS time does not (driving your system time) . Thanks in advance. Sincerely, Ron -- (PS - If you email me and don't get a quick response, don't be concerned. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new messages very quickly. If you need a reply and have not heard from me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude AT c3energy.com ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
On 3/14/2012 7:14 AM, David Lord wrote: Ron Frazier (NTP) wrote: On 3/13/2012 5:39 PM, David Lord wrote: Ron Frazier (NTP) wrote: On 3/13/2012 2:40 PM, Chris Albertson wrote: On Tue, Mar 13, 2012 at 9:52 AM, Ron Frazier (NTP) timekeepingntpl...@c3energy.com wrote: Hi all, I just woke up to a 50 SECOND clock error. Prior to the error, with my PC locked into the GPS and the internet servers noselected, here's what my peerstats looked like. Baseline is the GPS. Colored lines are internet servers. http://dl.dropbox.com/u/9879631/drifting01-peerstats.20120312.jpg Looks to me like that GPS, maybe lock lock and was able to coast on hold over for a while then fell off a cliff. If you have a log of satellite signal to noise ratios you might be able to figure out why. The internet servers appear to be 100% reliable seeing as they all agree. These kinds of things are why some hobbysts end up buying multiple GPS (different brands) Otherwise it is hard to sort out a GPS firmware bug from a solar storm or just that there were not sats visable to your indoor antenna for a few minutes I think your goal is to learn about all of this so these problems are a good thing. No one learns much from working systems. But if the goal is a reliable NTP server, the pool NTP servers can't be beat except by a good timing mode GPS, that has good self diagnostics and PPS. The self diagnostics part is important The link you quoted just now is not the one that bugs me so much today. This one is the one that bugs me today, where my clock was stepped by 50 seconds for some reason. http://dl.dropbox.com/u/9879631/drifting02b%20-%20peerstats%20insane.jpg I'm on a text mostly system so why do you require me to use a web browser to help you? What is your current ntp.conf, ntpd version, operating system and response of ntpq -crv -p after ntpd has had at least a day to stabilise? Not so long ago you posted that you had an offset within +/- 6 ms but didn't give any evidence. Response from ntpq -crv -p or better a day from peer_summary or couple of days from loop_summary would be enough. David When I get the Sure board, I plan to hang it on the pc in tandem with this GPS and compare. Sincerely, Ron Hi David L., I just figured the images and dropbox would be the fastest way to distribute the information. I didn't think I could attach files to messages going to the NTP questions mailing list. I'll be glad to provide stats files if anyone is interested. Just tell me how to distribute them. Based on advice from David Taylor, I just changed my configuration. Previously, I had only the GPS selectable and the internet servers noselected for testing purposes to try to determine where a slow drifting behavior is coming from. Now, I have changed that so the GPS is noselected and the New York NIST server is the preferred and only selectable peer. I am monitoring the GPS and other internet servers for comparison. So, it will be a couple of days before this configuration accumulates some stats files. Even though I have been tinkering with this GPS for a couple of months, I have never seen anything like the 50 second jump I started this thread about. That problem may not be reproducible for some time, if at all. Faulty GPS, incorrect configuration, anybodies guess? Internet servers give me an rms offset about 610us, whilst GPS with PPS gives about 4us. There are day to day variations and some rare 'events' when GPS or an internet server goes bad. You must LIVE on the internet backbone and have blazing fast routers to get performance like that. My typical performance from internet servers is offsets of + / - 60 ms. GPS without PPS, Globalsat BR304, wasn't worth using as ntp source due to large variations in offset from the NMEA sentences that were tried with RMC being best giving 50% of offsets under 10ms but maximum offsets being near 100ms. With my BU-353, which is similar, by setting the baud rate to 57,600, programming for ONLY GPGGA sentence, and polling every 8 seconds, I can keep my offsets from the GPS's estimate of true time to usually around + / - 5 ms with spikes to 10 ms and almost never higher. If I use ONLY the GPZDA sentence, which is essentially fixed length and reports only time, I can get that down to + / - 3 ms most of the time with spikes to 6 ms. However, David Taylor pointed out that the GPZDA sentence doesn't have any validity check field, and the GPGGA sentence does. We verified that the refclock.c code does check for this. So, I'm back to using GPGGA even with a bit more jitter. That way, if the GPS fails, ntpd is more likely to react gracefully. The problem with using my BU-353 in this way is that the start times for the NMEA sentence seem to wander over about 60 ms in either direction over a period of about 4 days. So, over a few days, my computer's time will drift away from true UTC time by that amount, and back
Re: [ntp:questions] Offset Average (Normal)?
On Mar 14, 8:03 am, David J Taylor david- tay...@blueyonder.co.uk.invalid wrote: Alby VA alb...@empire.org wrote in message news:0d4f588e-bab6-4706-826e-299149054...@i2g2000vbv.googlegroups.com... [] Thanks. That bug report sounds like the best plan of attack. Can that bug report be tracked to see if any action is taken? Yes, it's number 2164. See: http://bugs.ntp.org/show_bug.cgi?id=2164 Cheers, David Thanks. I'm going to watch and see what comes of this bug. I agree, the ntpq output should be able to give you nanosecond precision vs. microsecond. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Hi David, OK. You asked for it. 8-) Well, I actually suggested /all/ the Internet servers being enabled, allowing NTP to make its best choice. When I'm through testing, I'll open up the other internet servers as a backup in case the GPS fails. For now, I'm just running with one clock source at a time. Still trying to document and chase down this wandering effect. I ran with NY NIST as the only selectable clock source and monitoring the GPS for comparison all night. The results were horrible. My offsets from NIST time were in the + 65 ms / - 75 ms range. I had the polling interval set to start at 1 minute and go up to 4 minutes. There is way too much clock wander to even think about testing the accuracy of the GPS. I've gone back to polling the GPS every 8 seconds as the sole selectable clock source and monitoring the internet servers for comparison. Over the short term, minutes to hours, my GPS, even with NMEA only, is by far the most accurate time source I have. Even if the NMEA signal wanders 70 ms either way over the course of a few days, it won't get any further off than I did using the internet server, and the clock will be much more consistent over shorter time frames. Here are the graphs. http://dl.dropbox.com/u/9879631/nynist01.jpg http://dl.dropbox.com/u/9879631/nynist02.jpg Sincerely, Ron I'm not surprised that using a single Internet server is worse than the GPS/USB, but that's not how NTP is designed to work. With two or more Internet servers active, your GPS 50-second glitch would not have affected your PC's timekeeping anything like as severely, when you have the GPS/USB included to help improve the offset and more like the narrow band (about 15 milliseconds wide) shown in: http://dl.dropbox.com/u/9879631/drifting01-peerstats.20120312.jpg Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Offset Average (Normal)?
Alby VA alb...@empire.org wrote in message news:ed7bfa7e-3754-43f0-bd72-0efc709cd...@s7g2000yqm.googlegroups.com... [] http://bugs.ntp.org/show_bug.cgi?id=2164 Thanks. I'm going to watch and see what comes of this bug. I agree, the ntpq output should be able to give you nanosecond precision vs. microsecond. I've not seen any reaction as yet. Maybe if it doesn't get approved for some reason you might want to chip in with support. It may also be that SNMP can report more accurate values directly, but when I last checked SNMP support wasn't yet in the Windows port (although Windows isn't yet accurate enough to need sub-microsecond precision!). I'll start a new thread about SNMP. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
On 3/14/2012 10:41 AM, David J Taylor wrote: Hi David, OK. You asked for it. 8-) Well, I actually suggested /all/ the Internet servers being enabled, allowing NTP to make its best choice. When I'm through testing, I'll open up the other internet servers as a backup in case the GPS fails. For now, I'm just running with one clock source at a time. Still trying to document and chase down this wandering effect. I ran with NY NIST as the only selectable clock source and monitoring the GPS for comparison all night. The results were horrible. My offsets from NIST time were in the + 65 ms / - 75 ms range. I had the polling interval set to start at 1 minute and go up to 4 minutes. There is way too much clock wander to even think about testing the accuracy of the GPS. I've gone back to polling the GPS every 8 seconds as the sole selectable clock source and monitoring the internet servers for comparison. Over the short term, minutes to hours, my GPS, even with NMEA only, is by far the most accurate time source I have. Even if the NMEA signal wanders 70 ms either way over the course of a few days, it won't get any further off than I did using the internet server, and the clock will be much more consistent over shorter time frames. Here are the graphs. http://dl.dropbox.com/u/9879631/nynist01.jpg http://dl.dropbox.com/u/9879631/nynist02.jpg Sincerely, Ron I'm not surprised that using a single Internet server is worse than the GPS/USB, but that's not how NTP is designed to work. With two or more Internet servers active, your GPS 50-second glitch would not have affected your PC's timekeeping anything like as severely, when you have the GPS/USB included to help improve the offset and more like the narrow band (about 15 milliseconds wide) shown in: http://dl.dropbox.com/u/9879631/drifting01-peerstats.20120312.jpg Cheers, David OK. Here are the loopstats from another computer for 7 days (in the chart). I don't have any peerstats for it. It has the same server list. One is preferred. All servers are active. Performance is no better. http://dl.dropbox.com/u/9879631/TAZ%20loopstats%202012-03-07%20to%202012-03-14.jpg http://dl.dropbox.com/u/9879631/ntp.conf-TAZ http://dl.dropbox.com/u/9879631/loopstats.20120313-TAZ http://dl.dropbox.com/u/9879631/loopstats.20120314-TAZ Sincerely, Ron -- (PS - If you email me and don't get a quick response, don't be concerned. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new messages very quickly. If you need a reply and have not heard from me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude AT c3energy.com ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] NTP, SNMP on FreeBSD 8.2
Folks, I'm interested to know whether my install of NTP on FreeBSD 8.2 includes SNMP support or not. If it doesn't, then I may try a recompile, but first: 1 - can anyone point me to the correct place to download the appropriate MIB? I did find: http://tools.ietf.org/html/draft-ietf-ntp-ntpv4-mib-07 but the MIB information is interspersed with page headers, and whilst I did try and edit it, I can't be sure it compiled, and hence a plain MIB would be preferable. I did look elsewhere but only found Meinberg and Cisco MIBs which could be proprietary. 2 - In the absence of a properly compiled MIB, can anyone point me to a numeric OID which should be visible if NTP/SNMP is running? Ideally, the OID corresponding to: ntpq -c rv 0 offset I can then use GetIF (or whatever) to look for that OID from my FreeBSD ssytem. Thanks, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Ron Frazier (NTP) wrote: On 3/14/2012 7:14 AM, David Lord wrote: Ron Frazier (NTP) wrote: Based on advice from David Taylor, I just changed my configuration. Previously, I had only the GPS selectable and the internet servers noselected for testing purposes to try to determine where a slow drifting behavior is coming from. Now, I have changed that so the GPS is noselected and the New York NIST server is the preferred and only selectable peer. I am monitoring the GPS and other internet servers for comparison. So, it will be a couple of days before this configuration accumulates some stats files. Even though I have been tinkering with this GPS for a couple of months, I have never seen anything like the 50 second jump I started this thread about. That problem may not be reproducible for some time, if at all. Faulty GPS, incorrect configuration, anybodies guess? Internet servers give me an rms offset about 610us, whilst GPS with PPS gives about 4us. There are day to day variations and some rare 'events' when GPS or an internet server goes bad. You must LIVE on the internet backbone and have blazing fast routers to get performance like that. My typical performance from internet servers is offsets of + / - 60 ms. Hi Ron I don't live on the internet backbone nor do I have blazingly fast anything. I have a slow 2Mbit/s ADSL connection. You must have a very broken internet connection to get offsets that high. A few times I've been routed by satelite or some wireless connection and I also sometimes use mobile broadband but still don't see offsets as large as 60ms. GPS without PPS, Globalsat BR304, wasn't worth using as ntp source due to large variations in offset from the NMEA sentences that were tried with RMC being best giving 50% of offsets under 10ms but maximum offsets being near 100ms. With my BU-353, which is similar, by setting the baud rate to 57,600, programming for ONLY GPGGA sentence, and polling every 8 seconds, I can keep my offsets from the GPS's estimate of true time to usually around + / - 5 ms with spikes to 10 ms and almost never higher. If I use ONLY the GPZDA sentence, which is essentially fixed length and reports only time, I can get that down to + / - 3 ms most of the time with spikes to 6 ms. However, David Taylor pointed out that the GPZDA sentence doesn't have any validity check field, and the GPGGA sentence does. We verified that the refclock.c code does check for this. So, I'm back to using GPGGA even with a bit more jitter. That way, if the GPS fails, ntpd is more likely to react gracefully. What are you using as a reference to verify the offsets you get are offsets from UTC? The problem with using my BU-353 in this way is that the start times for the NMEA sentence seem to wander over about 60 ms in either direction over a period of about 4 days. So, over a few days, my computer's time will drift away from true UTC time by that amount, and back again. However, over the short term, my pc's clock is much more stable than if I use internet servers as my primary source. Can you give your ntp.conf that result in that level of offset from internet servers? The ntp distribution might still have some advice and tools for selection of suitable sources. I just select from the list of uk public servers at ntp.org and try each one to get rtt and their sources then select the ones that are closest with different sources. If you don't want to do that you can specify your local ntp pool. You should select at least four sources. I have about eight different sources split between ntp0.lordynet.org and ntp1.lordynet.org. David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Ron Frazier (NTP) timekeepingntpl...@c3energy.com wrote in message news:4f60bc0c.8040...@c3energy.com... [] OK. Here are the loopstats from another computer for 7 days (in the chart). I don't have any peerstats for it. It has the same server list. One is preferred. All servers are active. Performance is no better. http://dl.dropbox.com/u/9879631/TAZ%20loopstats%202012-03-07%20to%202012-03-14.jpg http://dl.dropbox.com/u/9879631/ntp.conf-TAZ http://dl.dropbox.com/u/9879631/loopstats.20120313-TAZ http://dl.dropbox.com/u/9879631/loopstats.20120314-TAZ Sincerely, Ron That's horrible, Ron! Much worse than David Lord reports. It makes me want to ask a number of questions: - is this PC connected over wireless or wired? - what else is going through the router? Someone else downloading large files or using streaming audio or video? - who else might be sharing your connection? - what type of service do you have? Presumably not dial-up! But what speed? - having checked you speed, would you describe your connection as stable? The quiet periods (e.g early Monday morning, Tuesday lunchtime) are much nearer to what I would hope for, which makes me wonder whether something is interfering with the connection outside those times. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
On 2012-03-14, David J Taylor david-tay...@blueyonder.co.uk.invalid wrote: unruh un...@invalid.ca wrote in message news:I1T7r.36416$l12.35...@newsfe23.iad... [] Did you shut down and restart your computer? Did you perchance do this during the daylight savings time transition on a Windows system? Could the error be related to the fact that Windows like time on localtime not UTC? Windows uses UTC internally, not local time. Local time is simply a presentation layer issue. Windows is unaffected by a DST transition. That must be new, since windows certainly used to maintain system time as local time. Caused numberous headaches for people using both Windows and Linux. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
On 2012-03-14, Ron Frazier (NTP) timekeepingntpl...@c3energy.com wrote: On 3/14/2012 3:03 AM, unruh wrote: On 2012-03-13, Ron Frazier (NTP)timekeepingntpl...@c3energy.com wrote: Hi all, I just woke up to a 50 SECOND clock error. Prior to the error, with my PC locked into the GPS and the internet servers noselected, here's what my peerstats looked like. Baseline is the GPS. Colored lines are internet servers. http://dl.dropbox.com/u/9879631/drifting01-peerstats.20120312.jpg Looking at this graph, I see that the nmea source was already difting before the sudden jump. It lost 30ms wrt the other servers in the 20 hours beforehand. Then it went crazy for a while and jumped to 80 ms ahead. I agree that this does seem to be that gps device. Which one is it? But that jump is 120ms not 50 sec. I recently had a Garmin 18 go nuts-- giving massive amounts of noise. That's very interesting. David Taylor also said he saw this NMEA wandering effect on the Garmin. Did your Garmin recover? And, is it based on a SIRF chipset? No idea. It is the old Garmin 18LVC (not 18x) In another thread, someone else with a BU-353 said he saw an offset storm like the one in my graph. Sincerely, Ron Here is what was showing on the Meinberg Time Server Monitor when I woke up: http://dl.dropbox.com/u/9879631/drifting02a%20-%20insane.jpg And the graph of the peerstats for that time: http://dl.dropbox.com/u/9879631/drifting02b%20-%20peerstats%20insane.jpg The clock error was REAL, as confirmed by my atomic wrist watch. However, the loopstats graph for the same time period shows no problem with the GPS: http://dl.dropbox.com/u/9879631/drifting02c%20-%20gps%20NOT%20insane.jpg So, I shut down NTPD and reset the time with a batch file that calls ntpdate and querys the New York NIST server: http://dl.dropbox.com/u/9879631/drifting02d%20-%20set%20with%20ntpdate.jpg Here is the time server monitor shortly after NTPD restart: http://dl.dropbox.com/u/9879631/drifting02e%20-%20shortly%20after%20ntpd%20restart.jpg And after a 2nd restart: http://dl.dropbox.com/u/9879631/drifting02f%20-%202nd%20ntpd%20restart%20after%20insane.jpg And here are the current peerstats, which look normal. The offset to the internet servers tends to drift and will eventually cross the zero line and get positive. http://dl.dropbox.com/u/9879631/drifting02g%20-%20peerstats%20after%20insane%20and%202nd%20reset.jpg The GPS appears to have been stable all through this, and was never powered off or unplugged. It looks like NTPD went crazy and reset my clock for some reason. It also reset all of the remote servers at the same time? Since it was an offset of your system with respect to the remote systems. Here are the peerstats and loopstats during the insane period. http://dl.dropbox.com/u/9879631/loopstats.20120313-1-restart%20around%201350%20utc http://dl.dropbox.com/u/9879631/peerstats.20120313-1-insane Here is my current ntp.conf: http://dl.dropbox.com/u/9879631/ntp.conf My system is Windows 7, NTP 4.2.7p259, GPS GlobalSat BU-353 USB NMEA only with GPGGA sentence at 57,600 baud. If anyone can shed some light on what happened, please do. It's driving me bonkers. I don't believe the GPS is at fault, and I suspect NTPD. Again, the remote servers all agree. The GPS time does not (driving your system time) . Thanks in advance. Sincerely, Ron ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] semi OT - Fwd: PDF on precision frequency generation
I thought some here might like to see this slide show on precision frequency generation. It was posted on the time-nuts list. Ron Original Message Subject:[time-nuts] Found surfing the net - slides/presentation from FEI Date: Wed, 14 Mar 2012 10:36:33 -0700 From: Pete Lancashire p...@petelancashire.com Reply-To: Discussion of precise time and frequency measurement time-n...@febo.com To: Discussion of precise time and frequency measurement time-n...@febo.com may not be new to many, but to someone new on the list http://www.ieee.li/pdf/viewgraphs/precision_frequency_generation.pdf ___ time-nuts mailing list -- time-n...@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- (PS - If you email me and don't get a quick response, don't be concerned. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new messages very quickly. If you need a reply and have not heard from me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude AT c3energy.com ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
unruh un...@invalid.ca wrote in message news:HI48r.39505$zd5.1...@newsfe12.iad... On 2012-03-14, David J Taylor wrote: [] Windows uses UTC internally, not local time. Local time is simply a presentation layer issue. Windows is unaffected by a DST transition. That must be new, since windows certainly used to maintain system time as local time. Caused numberous headaches for people using both Windows and Linux. Not new at all. It's been that way since 1992 for the whole of the NT family. Perhaps you are thinking of what is stored in the real-time clock chip? Windows and UNIX have different conventions for that, Windows using wall-clock time. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
On 3/14/2012 12:35 PM, David J Taylor wrote: Ron Frazier (NTP) timekeepingntpl...@c3energy.com wrote in message news:4f60bc0c.8040...@c3energy.com... [] OK. Here are the loopstats from another computer for 7 days (in the chart). I don't have any peerstats for it. It has the same server list. One is preferred. All servers are active. Performance is no better. http://dl.dropbox.com/u/9879631/TAZ%20loopstats%202012-03-07%20to%202012-03-14.jpg http://dl.dropbox.com/u/9879631/ntp.conf-TAZ http://dl.dropbox.com/u/9879631/loopstats.20120313-TAZ http://dl.dropbox.com/u/9879631/loopstats.20120314-TAZ Sincerely, Ron That's horrible, Ron! Much worse than David Lord reports. It makes me want to ask a number of questions: Hi David T, NOW you understand. I have 4 PC's connected to the LAN, plus my wife's work computer 3 days / week, and on rare occasions my son's computer. All are connected by wifi. All do pretty mundane things: web browser, email, sometimes downloading patches, sometimes doing online backup. My 4 are running NTPD. 3 run windows most of the time and dual boot into linux. My 4th machine runs linux all the time. When my wife is here, she does a remote desktop type of thing into her work system. Two of my PC's are running Vista, one is running Windows 7. Those three dual boot into Ubuntu 11.04 and the always linux machine runs Ubuntu 11.04. Almost all the discussions I've had on this mailing list are for my Windows 7 machine. The path out of my house is: PC Wifi -- Wifi router -- wired router -- cable modem -- ISP -- internet - is this PC connected over wireless or wired? Wifi G - what else is going through the router? Someone else downloading large files or using streaming audio or video? See above. Normally, no huge data hogs. - who else might be sharing your connection? It's cable. Who knows? I also get cable TV and telephone through the same wire. - what type of service do you have? Presumably not dial-up! But what speed? Comcast Cable Just tested it with speedtest.net Ping to near city: 91 ms, Download: 29.63 Mbps, Upload: 5.3 Mbps - having checked you speed, would you describe your connection as stable? See above for speed. Generally, it's very stable. However, for the purposes we're discussing, I think it's latencies and delays that are the problem. As I mentioned in my reply to David L, I'm not concerned over trying to get stellar performance from internet servers. I just want to get a good GPS server system running and use the internet servers as a backup. Sincerely, Ron The quiet periods (e.g early Monday morning, Tuesday lunchtime) are much nearer to what I would hope for, which makes me wonder whether something is interfering with the connection outside those times. Cheers, David -- (PS - If you email me and don't get a quick response, don't be concerned. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new messages very quickly. If you need a reply and have not heard from me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude AT c3energy.com ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Hi David T, NOW you understand. I have 4 PC's connected to the LAN, plus my wife's work computer 3 days / week, and on rare occasions my son's computer. All are connected by wifi. All do pretty mundane things: web browser, email, sometimes downloading patches, sometimes doing online backup. My 4 are running NTPD. 3 run windows most of the time and dual boot into linux. My 4th machine runs linux all the time. When my wife is here, she does a remote desktop type of thing into her work system. Two of my PC's are running Vista, one is running Windows 7. Those three dual boot into Ubuntu 11.04 and the always linux machine runs Ubuntu 11.04. Almost all the discussions I've had on this mailing list are for my Windows 7 machine. The path out of my house is: PC Wifi -- Wifi router -- wired router -- cable modem -- ISP -- internet - is this PC connected over wireless or wired? Wifi G - what else is going through the router? Someone else downloading large files or using streaming audio or video? See above. Normally, no huge data hogs. - who else might be sharing your connection? It's cable. Who knows? I also get cable TV and telephone through the same wire. - what type of service do you have? Presumably not dial-up! But what speed? Comcast Cable Just tested it with speedtest.net Ping to near city: 91 ms, Download: 29.63 Mbps, Upload: 5.3 Mbps - having checked you speed, would you describe your connection as stable? See above for speed. Generally, it's very stable. However, for the purposes we're discussing, I think it's latencies and delays that are the problem. As I mentioned in my reply to David L, I'm not concerned over trying to get stellar performance from internet servers. I just want to get a good GPS server system running and use the internet servers as a backup. Sincerely, Ron Ron, Thanks for that clarification. I think you should be getting /very much/ better performance from your Internet servers. That ping is poor as well. Here I have 30 Mb/s down, just 1 Mb/s up, and NTP delays show as 18-34 ms (most in 22-30 ms). To that end, if your cable modem has multiple ports, connect one of the PCs direct to the CM and run it as your local NTP server. Wi-Fi doesn't help NTP. Later, you can add GPS/PPS to that PC as well. At the very least, connect your timekeeping PC direct to the wired router. No Wi-Fi! For my main NTP server, I got a low-powered and fan-less Intel Atom system, and it runs FreeBSD. It /only/ runs NTP, no interactive stuff at all. You might also consider getting rid of the two routers and just using the wireless one. You might also see whether you can run NTP on your router - perhaps it's a model which can run the DD-WRT firmware. I think some variants of DD-WRT can run NTP, but please check. I have a WRT 54GL in my system where I run the DD-WRT firmware. http://www.dd-wrt.com/site/index Online backup could well affect the performance of the connection for timekeeping, and your imminent Sure GPS/PPS will help enormously. Just some thoughts which may help you along the way. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
On 3/14/2012 4:00 PM, David J Taylor wrote: Hi David T, NOW you understand. I have 4 PC's connected to the LAN, plus my wife's work computer 3 days / week, and on rare occasions my son's computer. All are connected by wifi. All do pretty mundane things: web browser, email, sometimes downloading patches, sometimes doing online backup. My 4 are running NTPD. 3 run windows most of the time and dual boot into linux. My 4th machine runs linux all the time. When my wife is here, she does a remote desktop type of thing into her work system. Two of my PC's are running Vista, one is running Windows 7. Those three dual boot into Ubuntu 11.04 and the always linux machine runs Ubuntu 11.04. Almost all the discussions I've had on this mailing list are for my Windows 7 machine. The path out of my house is: PC Wifi -- Wifi router -- wired router -- cable modem -- ISP -- internet - is this PC connected over wireless or wired? Wifi G - what else is going through the router? Someone else downloading large files or using streaming audio or video? See above. Normally, no huge data hogs. - who else might be sharing your connection? It's cable. Who knows? I also get cable TV and telephone through the same wire. - what type of service do you have? Presumably not dial-up! But what speed? Comcast Cable Just tested it with speedtest.net Ping to near city: 91 ms, Download: 29.63 Mbps, Upload: 5.3 Mbps - having checked you speed, would you describe your connection as stable? See above for speed. Generally, it's very stable. However, for the purposes we're discussing, I think it's latencies and delays that are the problem. As I mentioned in my reply to David L, I'm not concerned over trying to get stellar performance from internet servers. I just want to get a good GPS server system running and use the internet servers as a backup. Sincerely, Ron Ron, Thanks for that clarification. I think you should be getting /very much/ better performance from your Internet servers. That ping is poor as well. Here I have 30 Mb/s down, just 1 Mb/s up, and NTP delays show as 18-34 ms (most in 22-30 ms). To that end, if your cable modem has multiple ports, connect one of the PCs direct to the CM and run it as your local NTP server. Wi-Fi doesn't help NTP. Later, you can add GPS/PPS to that PC as well. At the very least, connect your timekeeping PC direct to the wired router. No Wi-Fi! For my main NTP server, I got a low-powered and fan-less Intel Atom system, and it runs FreeBSD. It /only/ runs NTP, no interactive stuff at all. You might also consider getting rid of the two routers and just using the wireless one. You might also see whether you can run NTP on your router - perhaps it's a model which can run the DD-WRT firmware. I think some variants of DD-WRT can run NTP, but please check. I have a WRT 54GL in my system where I run the DD-WRT firmware. http://www.dd-wrt.com/site/index Online backup could well affect the performance of the connection for timekeeping, and your imminent Sure GPS/PPS will help enormously. Just some thoughts which may help you along the way. Cheers, David Hi David, I really appreciate all these suggestions you shared, as well as past ones. If I decide to revamp my network, I'll probably put some of them into use. However, that's not really practical right now. All the networking gear is in the basement and all the PC's are upstairs. I've already spent 2 months working on this GPS stuff and ignoring some other things I need to be doing. I think I'm just going to focus on getting the Sure board up and running on a time server when it comes and, perhaps, use my BU-353 as a backup time source, and use the internet servers as a third level backup source. Most of the time, I won't care what they're doing Hopefully, I can spend less time thinking about time and just know that my PC's clocks are right. Regardless, I'm going to continue to have an interest in the topic and have enjoyed all the discussions and learning that have occurred. It's just that I have to do at least a few other things besides this. Sincerely, Ron -- (PS - If you email me and don't get a quick response, don't be concerned. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new messages very quickly. If you need a reply and have not heard from me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude AT c3energy.com ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
On 3/14/2012 5:04 PM, Ron Frazier (NTP) wrote: On 3/14/2012 4:00 PM, David J Taylor wrote: Hi David T, NOW you understand. I have 4 PC's connected to the LAN, plus my wife's work computer 3 days / week, and on rare occasions my son's computer. All are connected by wifi. All do pretty mundane things: web browser, email, sometimes downloading patches, sometimes doing online backup. My 4 are running NTPD. 3 run windows most of the time and dual boot into linux. My 4th machine runs linux all the time. When my wife is here, she does a remote desktop type of thing into her work system. Two of my PC's are running Vista, one is running Windows 7. Those three dual boot into Ubuntu 11.04 and the always linux machine runs Ubuntu 11.04. Almost all the discussions I've had on this mailing list are for my Windows 7 machine. The path out of my house is: PC Wifi -- Wifi router -- wired router -- cable modem -- ISP -- internet - is this PC connected over wireless or wired? Wifi G - what else is going through the router? Someone else downloading large files or using streaming audio or video? See above. Normally, no huge data hogs. - who else might be sharing your connection? It's cable. Who knows? I also get cable TV and telephone through the same wire. - what type of service do you have? Presumably not dial-up! But what speed? Comcast Cable Just tested it with speedtest.net Ping to near city: 91 ms, Download: 29.63 Mbps, Upload: 5.3 Mbps - having checked you speed, would you describe your connection as stable? See above for speed. Generally, it's very stable. However, for the purposes we're discussing, I think it's latencies and delays that are the problem. As I mentioned in my reply to David L, I'm not concerned over trying to get stellar performance from internet servers. I just want to get a good GPS server system running and use the internet servers as a backup. Sincerely, Ron Ron, Thanks for that clarification. I think you should be getting /very much/ better performance from your Internet servers. That ping is poor as well. Here I have 30 Mb/s down, just 1 Mb/s up, and NTP delays show as 18-34 ms (most in 22-30 ms). To that end, if your cable modem has multiple ports, connect one of the PCs direct to the CM and run it as your local NTP server. Wi-Fi doesn't help NTP. Later, you can add GPS/PPS to that PC as well. At the very least, connect your timekeeping PC direct to the wired router. No Wi-Fi! For my main NTP server, I got a low-powered and fan-less Intel Atom system, and it runs FreeBSD. It /only/ runs NTP, no interactive stuff at all. You might also consider getting rid of the two routers and just using the wireless one. You might also see whether you can run NTP on your router - perhaps it's a model which can run the DD-WRT firmware. I think some variants of DD-WRT can run NTP, but please check. I have a WRT 54GL in my system where I run the DD-WRT firmware. http://www.dd-wrt.com/site/index Online backup could well affect the performance of the connection for timekeeping, and your imminent Sure GPS/PPS will help enormously. Just some thoughts which may help you along the way. Cheers, David Hi David, I really appreciate all these suggestions you shared, as well as past ones. If I decide to revamp my network, I'll probably put some of them into use. However, that's not really practical right now. All the networking gear is in the basement and all the PC's are upstairs. I've already spent 2 months working on this GPS stuff and ignoring some other things I need to be doing. I think I'm just going to focus on getting the Sure board up and running on a time server when it comes and, perhaps, use my BU-353 as a backup time source, and use the internet servers as a third level backup source. Most of the time, I won't care what they're doing Hopefully, I can spend less time thinking about time and just know that my PC's clocks are right. Regardless, I'm going to continue to have an interest in the topic and have enjoyed all the discussions and learning that have occurred. It's just that I have to do at least a few other things besides this. Sincerely, Ron PS to my prior message. I don't think the problem so much is the delay to the internet servers, or even to get out of my house. NTPD is supposed to take care of that as long as it's pretty much symmetrical. I think the problem is that the Windows clock is like a wild tiger that doesn't want to be tamed and which is running every which way. For whatever reason, cpu load, heat, cosmic vibrations, whatever, the intrinsic frequency of the windows clock is always changing. In order to avoid beating up on the internet servers too much, I have to poll them at least every 4 minutes apart. If you let it, NTPD will extend that out to 16 minutes or more. So, when the clock source is polled, say the PC
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Ron Frazier (NTP) wrote: My typical performance from internet servers is offsets of + / - 60 ms. # Why not try some that have a closer network distance, or are at least geographically closer? # Georgia / Comcast Hints: tos cohort 1 restrict source nomodify pool us.pool.ntp.org iburst # supposed to give you geographically close servers # server rolex.usg.edu iburst # server timex.usg.edu iburst # server ntp2.stsn.net iburst # server tick.gatech.edu iburst # server time.intersecur.net iburst # server nist1-atl.ustiming.org iburst # server nist1.columbiacountyga.gov iburst # _Your_ ISP router is likely already picking up the closest couple of these all by itself already # server ntp01.comcastbusiness.net iburst # server ntp02.comcastbusiness.net iburst # server ntp.whm.comcastcommercial.net iburst # server ntp01.inflow.pa.bo.comcast.net iburst # server ntp02.inflow.pa.bo.comcast.net iburst # server ntp01.cmc.co.denver.comcast.net iburst # server ntp02.cmc.co.denver.comcast.net iburst # server cr01.atlanta.ga.ibone.comcast.net iburst # server pr01.atlanta.ga.ibone.comcast.net iburst # server pe02.56marietta.ga.ibone.comcast.net iburst # server te-0-1-0-4-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-3-5-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-3-5-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-1-4-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-2-2-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-1-5-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-4-3-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-0-12-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-0-10-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-3-12-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-4-12-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-4-12-0-0-cr01.atlanta.ga.ibone.comcast.net iburst # server pos-0-0-0-0-pe01.56marietta.ga.ibone.comcast.net iburst # ... -- E-Mail Sent to this address blackl...@anitech-systems.com will be added to the BlackLists. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Any chance these PCs are using a timesource (in the system somewhere) that isn't constant in the face of power management events? The other pink tiger (vs elephant) in your house could/would be the wifi - at least in terms of being a stable network type. Some of the bufferbloat http://www.bufferbloat.net/ folks have little nice to say about wireless. rick jones http://www.netperf.org/ -- oxymoron n, Hummer H2 with California Save Our Coasts and Oceans plates these opinions are mine, all mine; HP might not want them anyway... :) feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Sure gps looses all sattelite fixes
unruh un...@invalid.ca wrote in message news:wf78r.33384$kv1.26...@newsfe03.iad... [] Just wanted to report here. I switched the antennae on the two Sure GPS I have. Both worked fine for about 4 days, and suddenly the antenna that had failed before failed again-- no sattelites found. So, I am sure it is the antenna that is failing. Sure has said that they will send me a new one, but it has not arrived yet. I've had this happen with GPS antennas from UK suppliers as well. They are consumer level items, so the odd failure is not unknown. The supplier replaced the item without question, although they may wanted the failed unit back. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Sure gps looses all sattelite fixes
On Wed, Mar 14, 2012 at 10:21 PM, David J Taylor david-tay...@blueyonder.co.uk.invalid wrote: unruh un...@invalid.ca wrote in message news:wf78r.33384$kv1.26...@newsfe03.iad... [] Just wanted to report here. I switched the antennae on the two Sure GPS I have. Both worked fine for about 4 days, and suddenly the antenna that had failed before failed again-- no sattelites found. So, I am sure it is the antenna that is failing. Sure has said that they will send me a new one, but it has not arrived yet. I've had this happen with GPS antennas from UK suppliers as well. They are consumer level items, so the odd failure is not unknown. The supplier replaced the item without question, although they may wanted the failed unit back. Look at item 180518378555 on eBay. These are very well built and not expensive. They mount to a 3/4 inch iron pipe flange with four machine screws. Inside the plastic radome is a helix antenna and an RF amp. The pointed shape keeps birds, ice and whatever off the antenna. There is an o-ring seal between the radome and the aluminum base plate The cable and it's connector can fit inside a waterproof 3/4 inch pipe. I'd expect it to last for decades, or until struck by lightening. Chris Albertson Redondo Beach, California ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
