Re: [time-nuts] Timing performance of servers
Dear Edgardo, On 10/25/2012 02:04 AM, Edgardo Molina wrote: Dear Mangus, I will allow myself to share a comment on your thread. Timing on windows servers is not one of their plausible strengths. This comes as no surprise, but I wanted some hard fact to assist in raising the awareness. The reason I raised it here is that I didn't have the hard facts at hand when I needed it, and I trust the time-nuts to have a diversity of facts laying around. :) It was clearly pointed out during the SIM conference last week at CENAM. In fact there was an interesting discussion about the drawbacks when using NTP Windows based servers and all kind of NTP appliances compared to full size Linux based NTP servers. Is there a presentation or even a paper to illustrate this? The example of what NIST is using nationwide for their servers set an example of good server hardware and linux to provide the nation's NTP pulse. Interesting. I have however pointed out that a downside to their strategy is that wide-spread set of servers assist to keep network effects down. In Sweden SP (NMI) and NETNOD operates redundant servers in 4 different locations, at SP and at the three main internet exchange-points. I haven't done any experiments with Windows for NTP services, still it could be interesting as to set a benchmark while comparing it to the Linux boxes. My gut feeling says that an undisciplined Windows can be anywhere, configuring a server for the SNTP brings it into decent shape for most workstation usages, shifting over to NTP is needed for many applications but even that won't compete with a Linux or BSD box. Being able to show that in a paper is better than arm-waving, even if most people here most probably would believe me without much fact. I am currently trying out the Domain Time II NTP client from Symmetricom for the thesis. I have to come back to Symmetricom's Miguel García to decide on purchasing a Domain Time II NTP client kit. How is the Mainberg NTP client different from the Symmetricom version? Have you tried both? I haven't tried either, as I rarely operate a Windows box. If not I will be more than glad to help comparing both if you can help me pointing out the source for a demo version of Mainberg's software. Meinberg's NTP is available in fullblown version from their website: http://www.meinberg.de/german/sw/ntp.htm (the link to that page is available on their front page under the dubious and hard to grasp title NTP Software Sownload) What they have done is essentially port the ntp.org NTP to Windows and gift-wrapped it a little in terms of installation. Maybe then an objective review of both clients will be in order, I will be more than glad to do it or to test them against Windows NTP services, appliances and/or Linux NTP boxes. I have at least an example of those at the office. Actually, doing this kind of measurement could be illustrative that your time may be quite dispersed. It helps to raise the question of what time is it really, how could I improve it and can there be an approval mark on the time I have. -13 Just my 2x10 cents. That's a large frequency deviation among time-nuts. :) Regards to you and the group, Many thanks! Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
David, On 10/25/2012 07:03 AM, David J Taylor wrote: Magnus, If it helps, I have my own measurements of the Meinberg NTP port and later versions running on Windows here: http://www.satsignal.eu/mrtg/performance_ntp.php Strategy: 1 - have one FreeBSD (not Linux) server, although this is now not essential, but it's nice as a confirmation that the rest is working OK. 2 - Configure some Windows PCs as stratum-1 servers fed from GPS. On the plots above, PCs Alta, Bacchus, Feenix and Stamsund are acting as stratum-1 servers. These all have serial port connections, and cover the OS range Windows 2000, XP, Win-7/32 and Win-7/64. All are using the kernel-mode serial port driver patch developed by Dave Hart. PC Pixie is the FreeBSD box. 3 - For the client PCs, use a fixed 32-second polling interval to the local stratum-1 servers, with Internet servers as a backup polled at 1024 seconds, resulting in a configuration file something like: ___ # Use drift file driftfile C:\Tools\NTP\etc\ntp.drift # Use specific local NTP servers server 192.168.0.3 iburst minpoll 5 maxpoll 5 prefer # Pixie server 192.168.0.2 iburst minpoll 5 maxpoll 5 # Feenix server 192.168.0.7 iburst minpoll 5 maxpoll 5 # Stamsund # Use pool NTP servers pool uk.pool.ntp.org iburst minpoll 10 ___ The client performance varies, with some of the best results being on a Windows-8 Wi-Fi connected PC which seems to have very good drivers (PC Bergen). Jitter is 40 - 110 microseconds. Windows XP also shows low jitter, but greater offset (within 250 microseconds). Windows Vista was the worst performer I had, but that PC has now been retired. There are discussions in progress at the moment about improving Windows-Vista and Windows-7 as a Windows time interval setting and reporting bug has been discovered, particularly affecting NTP. Lovely! I'm impressed. What's the reasons for the offsets? Can't your tool handle negative values? It would be good to have min, max, max-min, avg, std.dev values without offsets to help illustrate worst-case behaviour as well as average performance and noise energy. The more advanced plotter would show MADEV, TDEV and MTIE plots. Ah well. Would it be possible to set up so you could measure deviation on SNTP and undisciplined machines? PS. Have my summerhouse not to far away from the town Ystad. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
On 10/25/2012 01:17 PM, Bob Camp wrote: Hi Judah Levine (probably spelled his name wrong) from NIST has a series of papers on this. They go back into the 90's. For once you got his name right :) I will go back to his papers (NIST has 106 papers with his name on it) as there is surely a lot of things that he written that can be useful. However, I wonder if he ever bothered to illustrate the issues that I wanted to educate folks with. Judah showed the NIST time clock labs for us. They are now up to 386 based machines to maintain the NIST time-scales. They only do work every 12 min anyway, so it doesn't really care if they can cut time from 4 s to 0,4 s. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Sarah, On 10/25/2012 06:44 PM, Sarah White wrote: 1) Thanks magnus. This is something I'm quite interested in: I'm not the only one doing testing for Microsoft NT 5.x and higher against NTP-type synchronization. It's actually high enough quality such that a Windows server running NTP with a refclock provides significantly better time than the public NTP servers. Here are a few writeups I've been using for reference, and I've been testing and duplicating some of the listed configurations, hoping for my own writeups: http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html (basic timing) http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html (connected to refclock, timing was better than 50 microseconds jitter, averaging less than 10 microseconds) Am actively in the process of getting everything to replace my own navigation GPS refclock with a timing mode one. At this point I just need to find a good antenna... That's a whole lot of information there. Many thanks for those links. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
David, [] Lovely! I'm impressed. What's the reasons for the offsets? Can't your tool handle negative values? It would be good to have min, max, max-min, avg, std.dev values without offsets to help illustrate worst-case behaviour as well as average performance and noise energy. The more advanced plotter would show MADEV, TDEV and MTIE plots. Ah well. Would it be possible to set up so you could measure deviation on SNTP and undisciplined machines? PS. Have my summerhouse not to far away from the town Ystad. Cheers, Magnus ___ I'm glad the information was helpful, Magnus. Yes, the tool I use - MRTG - can't handle negative values, and I haven't yet had the need or enthusiasm to convert to RRDtool which likely can. I do also collect the normal NTP statistics on some PCs and wrote an NTP Plotter program to analyse those here: http://www.satsignal.eu/software/net.htm#NTPplotter Move your mouse over the list of plots below to see the different plots. It doesn't include the more advanced statistics which you mention. The plots in MRTG are from a Perl script which uses ntpq and interprets the output into the two numbers needed for an MRTG plot. Another tool I offer is my NTP Monitor program: http://www.satsignal.eu/software/net.htm#NTPmonitor This tries to use NTP or time protocol to determine the time on a remote PC, and plots it against a reference such as a local PC. It's a coarser tool than using the NTP statistics, and was designed when my own time keeping was much worse, and I had no local stratum-1 servers. You could possibly do something simialr in Perl and use that to feed MRTG. PS. We know Sweden and Norway from holiday visits, and Ystad from the excellent Wallander TV series (in Swedish)! A Northern Lights Norway trip is written up here: http://www.satsignal.eu/Hols/2010/NorthernNorway/index.html Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Dear Magnus, I do not have a reference for the performance of Windows as NTP server. This has been a busy week and long working nights. It is a logical workload after being absent for nearly two weeks : ) I will browse the web and NIST to find some solid references to this issue. I am still enthusiastic about doing the side by side comparison for measuring various parameters between a Windows and a Linux box running NTP. It will require time to set the test but the contribution could be interesting, specially if no work has been done previously. I will use my spare time this weekend to search for information on the subject. Regards, Edgardo Molina Dirección IPTEL www.iptel.net.mx T : 55 55 55202444 M : 04455 20501854 Piensa en Bits SA de CV Información anexa: CONFIDENCIALIDAD DE INFORMACION Este mensaje tiene carácter confidencial. Si usted no es el destinarario de este mensaje, le suplicamos se lo notifique al remitente mediante un correo electrónico y que borre el presente mensaje y sus anexos de su computadora sin retener una copia de los mismos. Queda estrictamente prohibido copiar este mensaje o hacer usode el para cualquier propósito o divulgar su en forma parcial o total su contenido. Gracias. NON-DISCLOSURE OF INFORMATION This email is strictly confidential and may also be privileged. If you are not the intended recipient please immediately advise the sender by replying to this e-mail and then deleting the message and its attachments from your computer without keeping a copy. It is strictly forbidden to copy it or use it for any purpose or disclose its contents to any third party. Thank you. On Oct 27, 2012, at 8:47 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Dear Edgardo, On 10/25/2012 02:04 AM, Edgardo Molina wrote: Dear Mangus, I will allow myself to share a comment on your thread. Timing on windows servers is not one of their plausible strengths. This comes as no surprise, but I wanted some hard fact to assist in raising the awareness. The reason I raised it here is that I didn't have the hard facts at hand when I needed it, and I trust the time-nuts to have a diversity of facts laying around. :) It was clearly pointed out during the SIM conference last week at CENAM. In fact there was an interesting discussion about the drawbacks when using NTP Windows based servers and all kind of NTP appliances compared to full size Linux based NTP servers. Is there a presentation or even a paper to illustrate this? The example of what NIST is using nationwide for their servers set an example of good server hardware and linux to provide the nation's NTP pulse. Interesting. I have however pointed out that a downside to their strategy is that wide-spread set of servers assist to keep network effects down. In Sweden SP (NMI) and NETNOD operates redundant servers in 4 different locations, at SP and at the three main internet exchange-points. I haven't done any experiments with Windows for NTP services, still it could be interesting as to set a benchmark while comparing it to the Linux boxes. My gut feeling says that an undisciplined Windows can be anywhere, configuring a server for the SNTP brings it into decent shape for most workstation usages, shifting over to NTP is needed for many applications but even that won't compete with a Linux or BSD box. Being able to show that in a paper is better than arm-waving, even if most people here most probably would believe me without much fact. I am currently trying out the Domain Time II NTP client from Symmetricom for the thesis. I have to come back to Symmetricom's Miguel García to decide on purchasing a Domain Time II NTP client kit. How is the Mainberg NTP client different from the Symmetricom version? Have you tried both? I haven't tried either, as I rarely operate a Windows box. If not I will be more than glad to help comparing both if you can help me pointing out the source for a demo version of Mainberg's software. Meinberg's NTP is available in fullblown version from their website: http://www.meinberg.de/german/sw/ntp.htm (the link to that page is available on their front page under the dubious and hard to grasp title NTP Software Sownload) What they have done is essentially port the ntp.org NTP to Windows and gift-wrapped it a little in terms of installation. Maybe then an objective review of both clients will be in order, I will be more than glad to do it or to test them against Windows NTP services, appliances and/or Linux NTP boxes. I have at least an example of those at the office. Actually, doing this kind of measurement could be illustrative that your time may be quite dispersed. It helps to raise the question of what time is it really, how could I improve it and can there be an approval mark on the time I have. -13 Just my 2x10cents. That's a large frequency
Re: [time-nuts] Timing performance of servers
Dear Edgardo, On 10/27/2012 07:41 PM, Edgardo Molina wrote: Dear Magnus, I do not have a reference for the performance of Windows as NTP server. This has been a busy week and long working nights. It is a logical workload after being absent for nearly two weeks : ) I will browse the web and NIST to find some solid references to this issue. I am still enthusiastic about doing the side by side comparison for measuring various parameters between a Windows and a Linux box running NTP. It will require time to set the test but the contribution could be interesting, specially if no work has been done previously. I will use my spare time this weekend to search for information on the subject. A wealth of information has already been show in this thread. I'm sure there is more out there. I wonder to what degrees the different methods to illustrate errors have been used. Frequency stability for traditional white, flicker and random noises we illustrate with (modified) Allan Deviation, but it is maybe not the best method for illustrate temperature shift variants as well as the noise of packet networks. Similar for phase stability, where TDEV is being used. Typical way to illustrate time effect of systematic noises in telecom networks is the MTIE measure, which aids in showing the buffersizes and clock recovery PLL bandwidth needs, which also the traditional sinusoidal tolerance curves does. There are also new methods like MAFE for the packet world. What will happen on lost of reference and the hold over properties can also be of interest. Then systematics will surely dominate. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Hi If you are running a non-RTOS, one test parameter should be a significant variation in the workload on the server. Bob On Oct 27, 2012, at 2:34 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Dear Edgardo, On 10/27/2012 07:41 PM, Edgardo Molina wrote: Dear Magnus, I do not have a reference for the performance of Windows as NTP server. This has been a busy week and long working nights. It is a logical workload after being absent for nearly two weeks : ) I will browse the web and NIST to find some solid references to this issue. I am still enthusiastic about doing the side by side comparison for measuring various parameters between a Windows and a Linux box running NTP. It will require time to set the test but the contribution could be interesting, specially if no work has been done previously. I will use my spare time this weekend to search for information on the subject. A wealth of information has already been show in this thread. I'm sure there is more out there. I wonder to what degrees the different methods to illustrate errors have been used. Frequency stability for traditional white, flicker and random noises we illustrate with (modified) Allan Deviation, but it is maybe not the best method for illustrate temperature shift variants as well as the noise of packet networks. Similar for phase stability, where TDEV is being used. Typical way to illustrate time effect of systematic noises in telecom networks is the MTIE measure, which aids in showing the buffersizes and clock recovery PLL bandwidth needs, which also the traditional sinusoidal tolerance curves does. There are also new methods like MAFE for the packet world. What will happen on lost of reference and the hold over properties can also be of interest. Then systematics will surely dominate. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
On 10/27/2012 9:47 AM, Magnus Danielson wrote: Dear Edgardo, On 10/25/2012 02:04 AM, Edgardo Molina wrote: Dear Mangus, I will allow myself to share a comment on your thread. Timing on windows servers is not one of their plausible strengths. This comes as no surprise, but I wanted some hard fact to assist in raising the awareness. The reason I raised it here is that I didn't have the hard facts at hand when I needed it, and I trust the time-nuts to have a diversity of facts laying around. :) It was clearly pointed out during the SIM conference last week at CENAM. In fact there was an interesting discussion about the drawbacks when using NTP Windows based servers and all kind of NTP appliances compared to full size Linux based NTP servers. Is there a presentation or even a paper to illustrate this? The example of what NIST is using nationwide for their servers set an example of good server hardware and linux to provide the nation's NTP pulse. Interesting. I have however pointed out that a downside to their strategy is that wide-spread set of servers assist to keep network effects down. In Sweden SP (NMI) and NETNOD operates redundant servers in 4 different locations, at SP and at the three main internet exchange-points. I haven't done any experiments with Windows for NTP services, still it could be interesting as to set a benchmark while comparing it to the Linux boxes. My gut feeling says that an undisciplined Windows can be anywhere, configuring a server for the SNTP brings it into decent shape for most workstation usages, shifting over to NTP is needed for many applications but even that won't compete with a Linux or BSD box. Being able to show that in a paper is better than arm-waving, even if most people here most probably would believe me without much fact. I am currently trying out the Domain Time II NTP client from Symmetricom for the thesis. I have to come back to Symmetricom's Miguel García to decide on purchasing a Domain Time II NTP client kit. How is the Mainberg NTP client different from the Symmetricom version? Have you tried both? I haven't tried either, as I rarely operate a Windows box. If not I will be more than glad to help comparing both if you can help me pointing out the source for a demo version of Mainberg's software. Meinberg's NTP is available in fullblown version from their website: http://www.meinberg.de/german/sw/ntp.htm (the link to that page is available on their front page under the dubious and hard to grasp title NTP Software Sownload) What they have done is essentially port the ntp.org NTP to Windows and gift-wrapped it a little in terms of installation. Maybe then an objective review of both clients will be in order, I will be more than glad to do it or to test them against Windows NTP services, appliances and/or Linux NTP boxes. I have at least an example of those at the office. Actually, doing this kind of measurement could be illustrative that your time may be quite dispersed. It helps to raise the question of what time is it really, how could I improve it and can there be an approval mark on the time I have. -13 Just my 2x10cents. That's a large frequency deviation among time-nuts. :) Regards to you and the group, Many thanks! Cheers, Magnus 1) Meinberg technically hasn't done any porting, it's an installer for ntp binaries themselves, which are simply compiled for a target other than bsd / solaris / linux. There aren't any under the hood changes required. I could just as easily compile a windows binary using: 1a) The copy of gcc shipped by microsoft in the services for unix applications / SUA SDK. 1b) Or the one gentoo provides when using gentoo prefix (gentoo's own package manager can be run natively on windows via microsoft's compliant layer AKA interix) 1c) Or even bootstrap, compile my own windows-native posix-type gcc compiler (newer version or otherwise), and build ntp from source with my own compiler. 1d) alternatively, do what meinberg did, using a mingw gcc compile target (mingw gcc compiler adjusts dependencies slightly by basically just building against microsoft's C libraries and APIs which are already installed because so mucch of the windows OS already needs them to be in place) 1e) cygwin has been working well for many things for more than 10 years, providing their own 1f) potentially, the NTP source itself compiles unmodified on some version of microsoft's visual C compiler, or some other windows compiler 1x) In fact, other than compiling ntp from source, meinberg really only made things more convenient by providing an installer and a separate monitor tool. The underlying optimized code for synchronization of time via NTP protocol comes from the open-source code you can get from ntp.org. You can just as easily use meinberg's installer, and then drop-in a different binary provided by someone other than meinberg (or
Re: [time-nuts] Timing performance of servers
On 10/27/2012 09:06 PM, Sarah White wrote: Sorry to post such a long thing on the subject. Most of the work I do with accurate time involves network synchronization. Really, the NTP / SNTP protocol isn't nearly as high performance as Precision time protocol --- PTP is the latest technology to come out of the network time foundation, and NTP protocol has simply been around longer and as such, it is better known: http://networktimefoundation.org/projects/ The reason for this thread was not to necessarily get the best possible time, but to get away from severely affected time that was causing the dataloss issues. The one flaw that NTP has that motivated PTP was lack of hardware time-stamps. There are those that have implemented hardware time-stamping to NTP. It's unfortunate to compare NTP and PTP when it should be comparing software time-stamping and hardware time-stamping. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Hi Not to mention the issues with hardware time stamping over large scale / multi vendor networks. As soon as you cross your property line, things start to get messy…. Bob On Oct 27, 2012, at 4:37 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 10/27/2012 09:06 PM, Sarah White wrote: Sorry to post such a long thing on the subject. Most of the work I do with accurate time involves network synchronization. Really, the NTP / SNTP protocol isn't nearly as high performance as Precision time protocol --- PTP is the latest technology to come out of the network time foundation, and NTP protocol has simply been around longer and as such, it is better known: http://networktimefoundation.org/projects/ The reason for this thread was not to necessarily get the best possible time, but to get away from severely affected time that was causing the dataloss issues. The one flaw that NTP has that motivated PTP was lack of hardware time-stamps. There are those that have implemented hardware time-stamping to NTP. It's unfortunate to compare NTP and PTP when it should be comparing software time-stamping and hardware time-stamping. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
If you cannot see the horizon because of obstructions (what else?), these obstructions are likely to be a source of multipath. So while technically you do not need to see the horizon, any obstruction above the horizon could cause problems. Of course, distant trees or a hill are less likely to be a problem than your neighbor's garden shed with a tin roof. Also, some antennas are better at rejecting low angle signals than others. While the software can reject some undesired signals, it can only do so if the software can identify them as separate. If the multipath signal destructively interferes with the desired signal, there is not much the software can do. Didier KO4BB Sent from my Droid Razr 4G LTE wireless tracker. -Original Message- From: Rob Kimberley robkimber...@btinternet.com To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Thu, 25 Oct 2012 2:25 PM Subject: Re: [time-nuts] Timing performance of servers We used to filter out anything 10 - 20 degs above the horizon when setting up timing receivers. Typically there's a lot of noise down low (multipath and tropo effects). As long as you've got plenty of SVs you don't need to go way down to the horizon. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: 25 October 2012 20:09 To: li...@lazygranch.com; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Timing performance of servers On Thu, Oct 25, 2012 at 11:02 AM, li...@lazygranch.com wrote: The GPS seeing the horizon isn't required. Those satellites are filtered out by software. OK, technically it needs to see down to within 10 degrees of the horizon. But when you are choosing a location for the mast to the horizon or withing 10 degrees of it looks pretty much the same. I don't want a huge tree of building due south of the antenna. But for timing all you really need is to see most of the sky. It depends on if you want it to work or work as well as it can. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
On Fri, 26 Oct 2012 08:06:49 -0500 shali...@gmail.com wrote: Also, some antennas are better at rejecting low angle signals than others. While the software can reject some undesired signals, it can only do so if the software can identify them as separate. If the multipath signal destructively interferes with the desired signal, there is not much the software can do. Even if it's not destructively interfere, there is a certain time delay in the reflected signal. This will slightly shift the peak of the correlation function and thus change the detected phase of this satelite. And of course, this shift is not constant and different for each satelite. Attila Kinali -- There is no secret ingredient -- Po, Kung Fu Panda ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
On 26 Oct, 2012, at 08:06 , shali...@gmail.com wrote: If you cannot see the horizon because of obstructions (what else?), these obstructions are likely to be a source of multipath. So while technically you do not need to see the horizon, any obstruction above the horizon could cause problems. Of course, distant trees or a hill are less likely to be a problem than your neighbor's garden shed with a tin roof. Though, as I understand it, typical low-end GPS antennas are quite sensitive to multipath arriving from below the horizon as well. I think getting a sharp antenna cutoff at the horizon is the reason that high-end antennas have choke rings. Also, some antennas are better at rejecting low angle signals than others. While the software can reject some undesired signals, it can only do so if the software can identify them as separate. If the multipath signal destructively interferes with the desired signal, there is not much the software can do. Given that the transmitted C/A bandwidth is greater than 1 MHz, however, I'm not sure that it is possible for multipath signals to destructively interfere across the entire bandwidth; I think the issue is distortion, with some frequencies in the bandwidth suffering destructive interference while others are constructively interfered with. This can be compensated for in software, though it is much better not to have to. Dennis Ferguson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Hi If we are talking about timing performance of normal servers, multipath really isn't much of an issue. Unless you are running an OS with real time code (as in *not* Windows and *not* standard Linux) the timing stability isn't good enough to be bothered by the level of distortion that multipath injects. Yes, I have a fleet of Soekris NTP's that get around all that stuff. I would not call them servers. Yes, on an unloaded box you get pretty good numbers almost regardless of what you run. A server doing no work also isn't something I would call normal. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Dennis Ferguson Sent: Friday, October 26, 2012 1:53 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Timing performance of servers On 26 Oct, 2012, at 08:06 , shali...@gmail.com wrote: If you cannot see the horizon because of obstructions (what else?), these obstructions are likely to be a source of multipath. So while technically you do not need to see the horizon, any obstruction above the horizon could cause problems. Of course, distant trees or a hill are less likely to be a problem than your neighbor's garden shed with a tin roof. Though, as I understand it, typical low-end GPS antennas are quite sensitive to multipath arriving from below the horizon as well. I think getting a sharp antenna cutoff at the horizon is the reason that high-end antennas have choke rings. Also, some antennas are better at rejecting low angle signals than others. While the software can reject some undesired signals, it can only do so if the software can identify them as separate. If the multipath signal destructively interferes with the desired signal, there is not much the software can do. Given that the transmitted C/A bandwidth is greater than 1 MHz, however, I'm not sure that it is possible for multipath signals to destructively interfere across the entire bandwidth; I think the issue is distortion, with some frequencies in the bandwidth suffering destructive interference while others are constructively interfered with. This can be compensated for in software, though it is much better not to have to. Dennis Ferguson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
On Fri, 26 Oct 2012 12:53:02 -0500, Dennis Ferguson dennis.c.fergu...@gmail.com wrote: Also, some antennas are better at rejecting low angle signals than others. While the software can reject some undesired signals, it can only do so if the software can identify them as separate. If the multipath signal destructively interferes with the desired signal, there is not much the software can do. Given that the transmitted C/A bandwidth is greater than 1 MHz, however, I'm not sure that it is possible for multipath signals to destructively interfere across the entire bandwidth; I think the issue is distortion, with some frequencies in the bandwidth suffering destructive interference while others are constructively interfered with. This can be compensated for in software, though it is much better not to have to. Dennis Ferguson I thought the problem for GPS was not frequency selective fading caused by multipath but locking onto the delayed signal and generating the wrong range to the satellite. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
-Original Message- From: li...@lazygranch.com [] Just a FYI here, using Dave's logging program, I found large errors in NTP when the antivirus did its thing. I don't know if it was due to CPU activity interfering with NTP or the cabinet heating up when the antivirus was running. Take a look at the plots for Bacchus: http://www.satsignal.eu/mrtg/performance_bacchus.php There is a disk optimiser which kicks in on Wednesday at 03:00 UTC, and the box goes to 100% CPU for an hour. The offset reported by NTP goes from 0 to about +1 millisecond, and recovers over the next 150 minutes or so after the CPU use goes back to its near-zero resting level. With the PCs as stratum-1 servers, ambient or usage induced temperature variations do appear to be the main source of error, but not with Windows-7 client PCs served over the LAN. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
http://www.meinberg.de/english/sw/ntp.htm You can get NTP for windows and also their NTP Monitor. Free download. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Edgardo Molina Sent: 25 October 2012 01:05 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Timing performance of servers Dear Mangus, I will allow myself to share a comment on your thread. Timing on windows servers is not one of their plausible strengths. It was clearly pointed out during the SIM conference last week at CENAM. In fact there was an interesting discussion about the drawbacks when using NTP Windows based servers and all kind of NTP appliances compared to full size Linux based NTP servers. The example of what NIST is using nationwide for their servers set an example of good server hardware and linux to provide the nation's NTP pulse. I haven't done any experiments with Windows for NTP services, still it could be interesting as to set a benchmark while comparing it to the Linux boxes. I am currently trying out the Domain Time II NTP client from Symmetricom for the thesis. I have to come back to Symmetricom's Miguel García to decide on purchasing a Domain Time II NTP client kit. How is the Mainberg NTP client different from the Symmetricom version? Have you tried both? If not I will be more than glad to help comparing both if you can help me pointing out the source for a demo version of Mainberg's software. Maybe then an objective review of both clients will be in order, I will be more than glad to do it or to test them against Windows NTP services, appliances and/or Linux NTP boxes. I have at least an example of those at the office. -13 Just my 2x10 cents. Regards to you and the group, Edgardo Molina Dirección IPTEL www.iptel.net.mx T : 55 55 55202444 M : 04455 20501854 Piensa en Bits SA de CV Información anexa: CONFIDENCIALIDAD DE INFORMACION Este mensaje tiene carácter confidencial. Si usted no es el destinarario de este mensaje, le suplicamos se lo notifique al remitente mediante un correo electrónico y que borre el presente mensaje y sus anexos de su computadora sin retener una copia de los mismos. Queda estrictamente prohibido copiar este mensaje o hacer usode el para cualquier propósito o divulgar su en forma parcial o total su contenido. Gracias. NON-DISCLOSURE OF INFORMATION This email is strictly confidential and may also be privileged. If you are not the intended recipient please immediately advise the sender by replying to this e-mail and then deleting the message and its attachments from your computer without keeping a copy. It is strictly forbidden to copy it or use it for any purpose or disclose its contents to any third party. Thank you. On Oct 24, 2012, at 5:47 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Fellow time-nuts, When spending time on a conference last week, I heard one interesting comment that they lost data due to bad timing on their Windows servers. Now, I know that the standard Windows uses SNTP in order to achieve the goal of having the timing of the machines sufficiently aligned to allow Kerberos authentication. SNTP suffice for that, as it needs to be a handful of minutes in line. If you need better performance than that, you should use NTP (and then download and install Meinbergs Windows-client for NTP). Then again, I would point out that for this type of data, it would most probably be better served on a Linux box. What should be a nice wake-up call for them would be a summation of how different strategies would give them clock precision of sufficient grade. So, does anyone know of such measurements presented anywhere? There are bits and pieces, but the ideal for this case would be if they where collected in one page/paper. This is an awareness thing, so that people can do a little more well-informed choices. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
http://www.meinberg.de/english/sw/ntp.htm You can get NTP for windows and also their NTP Monitor. Free download. Rob Kimberley = .. with user-oriented install instructions here: http://www.satsignal.eu/ntp/setup.html Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Hi Judah Levine (probably spelled his name wrong) from NIST has a series of papers on this. They go back into the 90's. Bob On Oct 24, 2012, at 6:47 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Fellow time-nuts, When spending time on a conference last week, I heard one interesting comment that they lost data due to bad timing on their Windows servers. Now, I know that the standard Windows uses SNTP in order to achieve the goal of having the timing of the machines sufficiently aligned to allow Kerberos authentication. SNTP suffice for that, as it needs to be a handful of minutes in line. If you need better performance than that, you should use NTP (and then download and install Meinbergs Windows-client for NTP). Then again, I would point out that for this type of data, it would most probably be better served on a Linux box. What should be a nice wake-up call for them would be a summation of how different strategies would give them clock precision of sufficient grade. So, does anyone know of such measurements presented anywhere? There are bits and pieces, but the ideal for this case would be if they where collected in one page/paper. This is an awareness thing, so that people can do a little more well-informed choices. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Thanks for that David. Rob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of David J Taylor Sent: 25 October 2012 09:51 To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Timing performance of servers http://www.meinberg.de/english/sw/ntp.htm You can get NTP for windows and also their NTP Monitor. Free download. Rob Kimberley = .. with user-oriented install instructions here: http://www.satsignal.eu/ntp/setup.html Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
On 10/24/2012 6:47 PM, Magnus Danielson wrote: Fellow time-nuts, When spending time on a conference last week, I heard one interesting comment that they lost data due to bad timing on their Windows servers. Now, I know that the standard Windows uses SNTP in order to achieve the goal of having the timing of the machines sufficiently aligned to allow Kerberos authentication. SNTP suffice for that, as it needs to be a handful of minutes in line. If you need better performance than that, you should use NTP (and then download and install Meinbergs Windows-client for NTP). Then again, I would point out that for this type of data, it would most probably be better served on a Linux box. What should be a nice wake-up call for them would be a summation of how different strategies would give them clock precision of sufficient grade. So, does anyone know of such measurements presented anywhere? There are bits and pieces, but the ideal for this case would be if they where collected in one page/paper. This is an awareness thing, so that people can do a little more well-informed choices. Cheers, Magnus 1) Thanks magnus. This is something I'm quite interested in: I'm not the only one doing testing for Microsoft NT 5.x and higher against NTP-type synchronization. It's actually high enough quality such that a Windows server running NTP with a refclock provides significantly better time than the public NTP servers. Here are a few writeups I've been using for reference, and I've been testing and duplicating some of the listed configurations, hoping for my own writeups: http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html (basic timing) http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html (connected to refclock, timing was better than 50 microseconds jitter, averaging less than 10 microseconds) Am actively in the process of getting everything to replace my own navigation GPS refclock with a timing mode one. At this point I just need to find a good antenna... 2) ... Changing subject slightly: Regardless of if I run linux vs bsd vs windows (will be testing multiple configurations of each, and doing writeups over the next few years as I test more and learn) I'll need a good external antenna for the new GPS I'm going to run. Anyone think I can get by with anything cheaper than a symmetricom 58532a antenna? I can probably get one (used) for less than $50 on ebay, but I'd really prefer to source something more entry-level for closer to $5 or $10 if possible. Any suggestions? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Hi If: 1) You are in a reasonable location (good sky view) 2) Don't have a great long cable run ( 50') 3) Are only after NTP time Then, you can get away with a pretty simple antenna. I likely won't last as long as a better one out in the weather though. If you shop the auction sites you can get reasonable antennas (Lucent / Trimble / Syneregy) for $30. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Sarah White Sent: Thursday, October 25, 2012 12:44 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Timing performance of servers On 10/24/2012 6:47 PM, Magnus Danielson wrote: Fellow time-nuts, When spending time on a conference last week, I heard one interesting comment that they lost data due to bad timing on their Windows servers. Now, I know that the standard Windows uses SNTP in order to achieve the goal of having the timing of the machines sufficiently aligned to allow Kerberos authentication. SNTP suffice for that, as it needs to be a handful of minutes in line. If you need better performance than that, you should use NTP (and then download and install Meinbergs Windows-client for NTP). Then again, I would point out that for this type of data, it would most probably be better served on a Linux box. What should be a nice wake-up call for them would be a summation of how different strategies would give them clock precision of sufficient grade. So, does anyone know of such measurements presented anywhere? There are bits and pieces, but the ideal for this case would be if they where collected in one page/paper. This is an awareness thing, so that people can do a little more well-informed choices. Cheers, Magnus 1) Thanks magnus. This is something I'm quite interested in: I'm not the only one doing testing for Microsoft NT 5.x and higher against NTP-type synchronization. It's actually high enough quality such that a Windows server running NTP with a refclock provides significantly better time than the public NTP servers. Here are a few writeups I've been using for reference, and I've been testing and duplicating some of the listed configurations, hoping for my own writeups: http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html (basic timing) http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html (connected to refclock, timing was better than 50 microseconds jitter, averaging less than 10 microseconds) Am actively in the process of getting everything to replace my own navigation GPS refclock with a timing mode one. At this point I just need to find a good antenna... 2) ... Changing subject slightly: Regardless of if I run linux vs bsd vs windows (will be testing multiple configurations of each, and doing writeups over the next few years as I test more and learn) I'll need a good external antenna for the new GPS I'm going to run. Anyone think I can get by with anything cheaper than a symmetricom 58532a antenna? I can probably get one (used) for less than $50 on ebay, but I'd really prefer to source something more entry-level for closer to $5 or $10 if possible. Any suggestions? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Look out for TNC connectors and 12v on the Symmetricons! Don Bob Camp Hi If: 1) You are in a reasonable location (good sky view) 2) Don't have a great long cable run ( 50') 3) Are only after NTP time Then, you can get away with a pretty simple antenna. I likely won't last as long as a better one out in the weather though. If you shop the auction sites you can get reasonable antennas (Lucent / Trimble / Syneregy) for $30. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Sarah White Sent: Thursday, October 25, 2012 12:44 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Timing performance of servers On 10/24/2012 6:47 PM, Magnus Danielson wrote: Fellow time-nuts, When spending time on a conference last week, I heard one interesting comment that they lost data due to bad timing on their Windows servers. Now, I know that the standard Windows uses SNTP in order to achieve the goal of having the timing of the machines sufficiently aligned to allow Kerberos authentication. SNTP suffice for that, as it needs to be a handful of minutes in line. If you need better performance than that, you should use NTP (and then download and install Meinbergs Windows-client for NTP). Then again, I would point out that for this type of data, it would most probably be better served on a Linux box. What should be a nice wake-up call for them would be a summation of how different strategies would give them clock precision of sufficient grade. So, does anyone know of such measurements presented anywhere? There are bits and pieces, but the ideal for this case would be if they where collected in one page/paper. This is an awareness thing, so that people can do a little more well-informed choices. Cheers, Magnus 1) Thanks magnus. This is something I'm quite interested in: I'm not the only one doing testing for Microsoft NT 5.x and higher against NTP-type synchronization. It's actually high enough quality such that a Windows server running NTP with a refclock provides significantly better time than the public NTP servers. Here are a few writeups I've been using for reference, and I've been testing and duplicating some of the listed configurations, hoping for my own writeups: http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html (basic timing) http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html (connected to refclock, timing was better than 50 microseconds jitter, averaging less than 10 microseconds) Am actively in the process of getting everything to replace my own navigation GPS refclock with a timing mode one. At this point I just need to find a good antenna... 2) ... Changing subject slightly: Regardless of if I run linux vs bsd vs windows (will be testing multiple configurations of each, and doing writeups over the next few years as I test more and learn) I'll need a good external antenna for the new GPS I'm going to run. Anyone think I can get by with anything cheaper than a symmetricom 58532a antenna? I can probably get one (used) for less than $50 on ebay, but I'd really prefer to source something more entry-level for closer to $5 or $10 if possible. Any suggestions? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
On Thu, Oct 25, 2012 at 9:44 AM, Sarah White kuze...@gmail.com wrote: Regardless of if I run linux vs bsd vs windows (will be testing multiple configurations of each, and doing writeups over the next few years as I test more and learn) I'll need a good external antenna for the new GPS I'm going to run. Anyone think I can get by with anything cheaper than a symmetricom 58532a antenna? I can probably get one (used) for less than $50 on ebay, but I'd really prefer to source something more entry-level for closer to $5 or $10 if possible. Any suggestions? Chris Albertson Redondo Beach, California Location matters a LOT more than the brand of antenna. In an ideal world a GPS antenna needs to see all the way to the horizon in all directions AND it needs to be far way from reflective objects that can cause multi path. Some times moving a foot or some is enough for an improvement. You will notice that the best timing mode antenna come inside enclosures made to shed water and snow. They are pointy or round on top. You don't need this feature if the antenna is looking out a window. In fact the small patch type antenna might be able to be place close to a window and get a better view of the sky. All that said. These are good and not expensive. ebay #270881742870 I have one of these on a mast and the cable fits inside the pipe/mast. the patch antenna is cheaper see #290739284641 One thing to watch is the kind of connectors. You don't want to have to use a chain of adaptors, N to F to BNC. Those can cost $5 each and certinly do not help the signal. For outdoors I like N type as they are 100% water proof. Some types of F are too but not all of them. Watch that you get a 5V volt antenna (unless you really want a 3.5 volt type) and get a co-axial type cable. Some have odd-ball multi-pin cables ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
The GPS seeing the horizon isn't required. Those satellites are filtered out by software. The timing GPSs are designed to be less sensitive to the horizon. -Original Message- From: Chris Albertson albertson.ch...@gmail.com Sender: time-nuts-boun...@febo.com Date: Thu, 25 Oct 2012 10:04:43 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Timing performance of servers On Thu, Oct 25, 2012 at 9:44 AM, Sarah White kuze...@gmail.com wrote: Regardless of if I run linux vs bsd vs windows (will be testing multiple configurations of each, and doing writeups over the next few years as I test more and learn) I'll need a good external antenna for the new GPS I'm going to run. Anyone think I can get by with anything cheaper than a symmetricom 58532a antenna? I can probably get one (used) for less than $50 on ebay, but I'd really prefer to source something more entry-level for closer to $5 or $10 if possible. Any suggestions? Chris Albertson Redondo Beach, California Location matters a LOT more than the brand of antenna. In an ideal world a GPS antenna needs to see all the way to the horizon in all directions AND it needs to be far way from reflective objects that can cause multi path. Some times moving a foot or some is enough for an improvement. You will notice that the best timing mode antenna come inside enclosures made to shed water and snow. They are pointy or round on top. You don't need this feature if the antenna is looking out a window. In fact the small patch type antenna might be able to be place close to a window and get a better view of the sky. All that said. These are good and not expensive. ebay #270881742870 I have one of these on a mast and the cable fits inside the pipe/mast. the patch antenna is cheaper see #290739284641 One thing to watch is the kind of connectors. You don't want to have to use a chain of adaptors, N to F to BNC. Those can cost $5 each and certinly do not help the signal. For outdoors I like N type as they are 100% water proof. Some types of F are too but not all of them. Watch that you get a 5V volt antenna (unless you really want a 3.5 volt type) and get a co-axial type cable. Some have odd-ball multi-pin cables ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
On Thu, Oct 25, 2012 at 11:02 AM, li...@lazygranch.com wrote: The GPS seeing the horizon isn't required. Those satellites are filtered out by software. OK, technically it needs to see down to within 10 degrees of the horizon. But when you are choosing a location for the mast to the horizon or withing 10 degrees of it looks pretty much the same. I don't want a huge tree of building due south of the antenna. But for timing all you really need is to see most of the sky. It depends on if you want it to work or work as well as it can. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
We used to filter out anything 10 - 20 degs above the horizon when setting up timing receivers. Typically there's a lot of noise down low (multipath and tropo effects). As long as you've got plenty of SVs you don't need to go way down to the horizon. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: 25 October 2012 20:09 To: li...@lazygranch.com; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Timing performance of servers On Thu, Oct 25, 2012 at 11:02 AM, li...@lazygranch.com wrote: The GPS seeing the horizon isn't required. Those satellites are filtered out by software. OK, technically it needs to see down to within 10 degrees of the horizon. But when you are choosing a location for the mast to the horizon or withing 10 degrees of it looks pretty much the same. I don't want a huge tree of building due south of the antenna. But for timing all you really need is to see most of the sky. It depends on if you want it to work or work as well as it can. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
The 20 degree cutoff is what I recall the starloc uses as a default. Now I don't know how important it is to filter those out by the response pattern of the antenna versus by software. -Original Message- From: Rob Kimberley robkimber...@btinternet.com Sender: time-nuts-boun...@febo.com Date: Thu, 25 Oct 2012 20:24:58 To: 'Discussion of precise time and frequency measurement'time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Timing performance of servers We used to filter out anything 10 - 20 degs above the horizon when setting up timing receivers. Typically there's a lot of noise down low (multipath and tropo effects). As long as you've got plenty of SVs you don't need to go way down to the horizon. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: 25 October 2012 20:09 To: li...@lazygranch.com; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Timing performance of servers On Thu, Oct 25, 2012 at 11:02 AM, li...@lazygranch.com wrote: The GPS seeing the horizon isn't required. Those satellites are filtered out by software. OK, technically it needs to see down to within 10 degrees of the horizon. But when you are choosing a location for the mast to the horizon or withing 10 degrees of it looks pretty much the same. I don't want a huge tree of building due south of the antenna. But for timing all you really need is to see most of the sky. It depends on if you want it to work or work as well as it can. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
On 10/25/12 11:02 AM, li...@lazygranch.com wrote: The GPS seeing the horizon isn't required. Those satellites are filtered out by software. The timing GPSs are designed to be less sensitive to the horizon. when tracking a satellite above the cutoff, you still want the antenna to not respond down to the horizon, because that might be where the multipath is coming from. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Dear Mangus, I will allow myself to share a comment on your thread. Timing on windows servers is not one of their plausible strengths. It was clearly pointed out during the SIM conference last week at CENAM. In fact there was an interesting discussion about the drawbacks when using NTP Windows based servers and all kind of NTP appliances compared to full size Linux based NTP servers. The example of what NIST is using nationwide for their servers set an example of good server hardware and linux to provide the nation's NTP pulse. I haven't done any experiments with Windows for NTP services, still it could be interesting as to set a benchmark while comparing it to the Linux boxes. I am currently trying out the Domain Time II NTP client from Symmetricom for the thesis. I have to come back to Symmetricom's Miguel García to decide on purchasing a Domain Time II NTP client kit. How is the Mainberg NTP client different from the Symmetricom version? Have you tried both? If not I will be more than glad to help comparing both if you can help me pointing out the source for a demo version of Mainberg's software. Maybe then an objective review of both clients will be in order, I will be more than glad to do it or to test them against Windows NTP services, appliances and/or Linux NTP boxes. I have at least an example of those at the office. -13 Just my 2x10 cents. Regards to you and the group, Edgardo Molina Dirección IPTEL www.iptel.net.mx T : 55 55 55202444 M : 04455 20501854 Piensa en Bits SA de CV Información anexa: CONFIDENCIALIDAD DE INFORMACION Este mensaje tiene carácter confidencial. Si usted no es el destinarario de este mensaje, le suplicamos se lo notifique al remitente mediante un correo electrónico y que borre el presente mensaje y sus anexos de su computadora sin retener una copia de los mismos. Queda estrictamente prohibido copiar este mensaje o hacer usode el para cualquier propósito o divulgar su en forma parcial o total su contenido. Gracias. NON-DISCLOSURE OF INFORMATION This email is strictly confidential and may also be privileged. If you are not the intended recipient please immediately advise the sender by replying to this e-mail and then deleting the message and its attachments from your computer without keeping a copy. It is strictly forbidden to copy it or use it for any purpose or disclose its contents to any third party. Thank you. On Oct 24, 2012, at 5:47 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Fellow time-nuts, When spending time on a conference last week, I heard one interesting comment that they lost data due to bad timing on their Windows servers. Now, I know that the standard Windows uses SNTP in order to achieve the goal of having the timing of the machines sufficiently aligned to allow Kerberos authentication. SNTP suffice for that, as it needs to be a handful of minutes in line. If you need better performance than that, you should use NTP (and then download and install Meinbergs Windows-client for NTP). Then again, I would point out that for this type of data, it would most probably be better served on a Linux box. What should be a nice wake-up call for them would be a summation of how different strategies would give them clock precision of sufficient grade. So, does anyone know of such measurements presented anywhere? There are bits and pieces, but the ideal for this case would be if they where collected in one page/paper. This is an awareness thing, so that people can do a little more well-informed choices. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Fellow time-nuts, When spending time on a conference last week, I heard one interesting comment that they lost data due to bad timing on their Windows servers. [] If you need better performance than that, you should use NTP (and then download and install Meinbergs Windows-client for NTP). Then again, I would point out that for this type of data, it would most probably be better served on a Linux box. What should be a nice wake-up call for them would be a summation of how different strategies would give them clock precision of sufficient grade. So, does anyone know of such measurements presented anywhere? [] Cheers, Magnus Magnus, If it helps, I have my own measurements of the Meinberg NTP port and later versions running on Windows here: http://www.satsignal.eu/mrtg/performance_ntp.php Strategy: 1 - have one FreeBSD (not Linux) server, although this is now not essential, but it's nice as a confirmation that the rest is working OK. 2 - Configure some Windows PCs as stratum-1 servers fed from GPS. On the plots above, PCs Alta, Bacchus, Feenix and Stamsund are acting as stratum-1 servers. These all have serial port connections, and cover the OS range Windows 2000, XP, Win-7/32 and Win-7/64. All are using the kernel-mode serial port driver patch developed by Dave Hart. PC Pixie is the FreeBSD box. 3 - For the client PCs, use a fixed 32-second polling interval to the local stratum-1 servers, with Internet servers as a backup polled at 1024 seconds, resulting in a configuration file something like: ___ # Use drift file driftfile C:\Tools\NTP\etc\ntp.drift # Use specific local NTP servers server 192.168.0.3iburstminpoll 5 maxpoll 5 prefer# Pixie server 192.168.0.2iburstminpoll 5 maxpoll 5# Feenix server 192.168.0.7iburstminpoll 5 maxpoll 5# Stamsund # Use pool NTP servers pool uk.pool.ntp.orgiburstminpoll 10 ___ The client performance varies, with some of the best results being on a Windows-8 Wi-Fi connected PC which seems to have very good drivers (PC Bergen). Jitter is 40 - 110 microseconds. Windows XP also shows low jitter, but greater offset (within 250 microseconds). Windows Vista was the worst performer I had, but that PC has now been retired. There are discussions in progress at the moment about improving Windows-Vista and Windows-7 as a Windows time interval setting and reporting bug has been discovered, particularly affecting NTP. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Timing performance of servers
Just a FYI here, using Dave's logging program, I found large errors in NTP when the antivirus did its thing. I don't know if it was due to CPU activity interfering with NTP or the cabinet heating up when the antivirus was running. -Original Message- From: David J Taylor david-tay...@blueyonder.co.uk Sender: time-nuts-boun...@febo.com Date: Thu, 25 Oct 2012 06:03:44 To: Time-Nutstime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Timing performance of servers Fellow time-nuts, When spending time on a conference last week, I heard one interesting comment that they lost data due to bad timing on their Windows servers. [] If you need better performance than that, you should use NTP (and then download and install Meinbergs Windows-client for NTP). Then again, I would point out that for this type of data, it would most probably be better served on a Linux box. What should be a nice wake-up call for them would be a summation of how different strategies would give them clock precision of sufficient grade. So, does anyone know of such measurements presented anywhere? [] Cheers, Magnus Magnus, If it helps, I have my own measurements of the Meinberg NTP port and later versions running on Windows here: http://www.satsignal.eu/mrtg/performance_ntp.php Strategy: 1 - have one FreeBSD (not Linux) server, although this is now not essential, but it's nice as a confirmation that the rest is working OK. 2 - Configure some Windows PCs as stratum-1 servers fed from GPS. On the plots above, PCs Alta, Bacchus, Feenix and Stamsund are acting as stratum-1 servers. These all have serial port connections, and cover the OS range Windows 2000, XP, Win-7/32 and Win-7/64. All are using the kernel-mode serial port driver patch developed by Dave Hart. PC Pixie is the FreeBSD box. 3 - For the client PCs, use a fixed 32-second polling interval to the local stratum-1 servers, with Internet servers as a backup polled at 1024 seconds, resulting in a configuration file something like: ___ # Use drift file driftfile C:\Tools\NTP\etc\ntp.drift # Use specific local NTP servers server 192.168.0.3iburstminpoll 5 maxpoll 5 prefer# Pixie server 192.168.0.2iburstminpoll 5 maxpoll 5# Feenix server 192.168.0.7iburstminpoll 5 maxpoll 5# Stamsund # Use pool NTP servers pool uk.pool.ntp.orgiburstminpoll 10 ___ The client performance varies, with some of the best results being on a Windows-8 Wi-Fi connected PC which seems to have very good drivers (PC Bergen). Jitter is 40 - 110 microseconds. Windows XP also shows low jitter, but greater offset (within 250 microseconds). Windows Vista was the worst performer I had, but that PC has now been retired. There are discussions in progress at the moment about improving Windows-Vista and Windows-7 as a Windows time interval setting and reporting bug has been discovered, particularly affecting NTP. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
