Re: [time-nuts] CW12-TIM
Hi As I recall from conversations with John over the years, the presentation he wrote was (for the most part) an effort to “dumb down” the subject for a more general audience … Bob On Jul 14, 2014, at 9:00 PM, Tom Van Baak wrote: >>> I think we need to have a "Time Nuts For Dummies" article written that >>> takes J. Vig's writing and puts it into much less of a technically rigorous > >> And maybe a recommended list of simple experiments that new time-nuts >> can perform. > > There's quite a list of resources at the main time-nuts page: >http://leapsecond.com/time-nuts.htm > > If playing with NTP is your interest, David Taylor's site is superb: >http://www.satsignal.eu/ntp/ > >> Maybe I can venture beyond the Raspberry Pi with NTP and PPS GPS >> ..how far does the rabbit hole go? > > Newcomers and experimenters also enjoy the powers of ten PDF: >http://leapsecond.com/ten/ > > /tvb > > > ___ > 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] CW12-TIM
>>I think we need to have a "Time Nuts For Dummies" article written that >>takes J. Vig's writing and puts it into much less of a technically rigorous > And maybe a recommended list of simple experiments that new time-nuts > can perform. There's quite a list of resources at the main time-nuts page: http://leapsecond.com/time-nuts.htm If playing with NTP is your interest, David Taylor's site is superb: http://www.satsignal.eu/ntp/ > Maybe I can venture beyond the Raspberry Pi with NTP and PPS GPS > ..how far does the rabbit hole go? Newcomers and experimenters also enjoy the powers of ten PDF: http://leapsecond.com/ten/ /tvb ___ 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] CW12-TIM
Sounds like a great idea, Maybe I can venture beyond the Raspberry Pi with NTP and PPS GPS ..how far does the rabbit hole go? Frits On 7/14/14, Scott Newell wrote: > At 04:09 PM 7/14/2014, saidj...@aol.com wrote: >> >>I think we need to have a "Time Nuts For Dummies" article written that >>takes J. Vig's writing and puts it into much less of a technically >> rigorous > > And maybe a recommended list of simple experiments that new time-nuts > can perform. > > -- > newell N5TNL > > ___ > 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. > -- vbradio.wordpress.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] CW12-TIM
yes you are right On 7/14/2014 2:41 PM, Scott Newell wrote: At 04:09 PM 7/14/2014, saidj...@aol.com wrote: I think we need to have a "Time Nuts For Dummies" article written that takes J. Vig's writing and puts it into much less of a technically rigorous And maybe a recommended list of simple experiments that new time-nuts can perform. ___ 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] Optical Distribution of 1PPS and IRIG
Hi There are indeed modules that will move a pps over fiber. They are not cheap. They also are not real good bang for the buck if you need millisecond level timing. Without guidance on what we are trying to do here it’s very tough to come up with much. NTP over a symmetrical route will indeed do the job (to some level) without using any additional fiber at all. 1588 over a dedicated pair (virtual or otherwise) would do a better job, and still probably be cheaper than any of the dedicated fiber solutions. Bob On Jul 14, 2014, at 3:25 PM, Hal Murray wrote: > > mafl...@theflynn.org said: >> I am working on a project where I need to transfer 1PPS approximately 120 >> meters between buildings.I cam borrow a pair of 62.5 fibers from IT/ >> telco to do so. > > Google for >fiber IRIG< gets plenty of hits. > > Raw PPS is a nasty case for fibers. You need some sort of > modulation/encoding, or derive it from the IRIG signal. > > The dynamic range that the receiver in a fiber setup can see is huge. All > the modules I've worked with include AGC. That needs a signal to listen to. > I haven't seen any with a time-constant slow enough to work with 1 PPS. > > If I wanted to send a PPS over fiber, I'd probably do something like this: > send the PPS using Manchester encoding. > that assumes you have a 20 MHz source clock synced to the PPS > at the receiver, use a PLL to make a 20 MHz clock, and use that to decode > the data > > The received PPS will be several clock cycles late. You can undo that with > with simple digital logic. Just delay it by 20,000,000 - N cycles. > Now it's only late by the fiber speed of light delay. (plus various digital > prop delays and clock-out delays) > > > > > -- > These are my opinions. I hate spam. > > > > ___ > 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] CW12-TIM
At 04:09 PM 7/14/2014, saidj...@aol.com wrote: I think we need to have a "Time Nuts For Dummies" article written that takes J. Vig's writing and puts it into much less of a technically rigorous And maybe a recommended list of simple experiments that new time-nuts can perform. -- newell N5TNL ___ 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] CW12-TIM
Good point. I am a sucker for great surplus equipment too, in fact I have two rooms full of stuff most of which is used from time to time.. I envy Tom's collection. I think we need to have a "Time Nuts For Dummies" article written that takes J. Vig's writing and puts it into much less of a technically rigorous 3 to 10 page article that makes timing accessible to the average product manager or systems engineer, and adds a hole bunch of GPS Disciplining explanation as well. This should be non-academic (who cares about Leesson's formulas digested to the N'th degree when simply looking for a lab reference) and should be fun and easy to read, but still get all the important points across. bye, Said In a message dated 7/12/2014 15:01:33 Pacific Daylight Time, mag...@rubidium.dyndns.org writes: Said, ... and deprive us from cheap surplus oscillators of good performance? What where you thinking? :) But I agree fully with your point, people don't understand how their poorly speced requirements translate into cost and design-time. Accurate time to the fs for no budget is what you can expect if they push their wishlist, but they have seen the E-18 numbers in some fancy article, so as is now possible. I think not (mixing time and frequency numbers is just what you can expect among other things). Also, ADEV numbers isn't everything, it can be a splendid answer to the incomplete and incorrect asked question. Cheers, Magnus On 07/12/2014 10:44 PM, saidj...@aol.com wrote: > Graham, > > I think that is the real challenge here: most folks don't know what > "precise" means for them. Timing is such a novel technology that most folks are > amazed that we are trying to get parts per trillion (or better) accuracy and > stability! > > We get customers all the time that want very precise timing, very good > phase noise, and overall very good performance but are only used to TCXO's with > maybe 10ppm frequency accuracy and cannot specify anything beyond that. > > The challenge is to explain the cost-benefit to them, like: > > 1ppm == $1 > 0.01ppm = $300 > 10ppt == $1500 > 0.1ppt == $$$ etc. > > Once dollars are mentioned, desired specifications usually are attained at > fairly quickly :) > > We recently had an inquiry that we forwarded to a major atomic oscillator > vendor, and the estimated $10 Million design cost and 10 year design time > quickly shut that idea down.. > > bye, > Said > > > In a message dated 7/12/2014 08:54:09 Pacific Daylight Time, > gh78...@gmail.com writes: > > Shane: > > The question I think that is being asked is ... > What does "precise" mean to you? > To the nearest order of magnitude, what kind of accuracy are you looking > for > on your three signals. This defines the kind of system you will need. > > This group normally aspires to the more accurate end of the scale. > > If you are doing simple time logging of some process, then you are > probably at the other end of the possible accuracy scale, and can > do things much more simply and cheaply. > > So ... > > 1 PPS: +/- 1 ns? 10 ns? 100 ns? 1 us? 10 us ? > NTP: +/-10 ms? 100 ms? 1 second? > 10 MHz: +/- 10E-6?10E-9? 10E-12? 10E-14? > > --- Graham > > == > > > On Sat, Jul 12, 2014 at 3:57 AM, Shane Morris > wrote: > >> Hal, >> >> As much as I'd like to explain the "big picture" in list, it would make > God >> awful noise - if you wish to know any details, I encourage you to respond >> to me off list. Given the fact that the robotics is so totally off topic, >> I'm not willing to discuss them here. Thats only out of respect to the >> topic of the list. The only real stipulations at this design part of the >> project is 10MHz out, 1PPS out, and NTP out. Please don't think I'm being >> narqy, I'm really not going to pollute the list with off topic chatter. I >> am more than happy to discuss off list, as and when. >> >> David, >> >> I was planning to use RaspberryPis in some part of the network, and of >> course, I must be silly, they have ethernet, and can run Real Time Linux >> (the LinuxCNC distros that have been made for control of CNC machines). > By >> the way, the whole network uses heterogeneous CPU types, I'm pretty >> agnostic to CPU type, as long as it does the job I need it to. The actual >> ethernet interface won't be as deterministic as we'd like, being chained > to >> the USB bus, but if one was not to put any other USB devices on, nor > attach >> anything that draws power, the USB performance would be good enough for >> second accuracy NTP frames. This is without any real analysis of any spec >> sheets, although I have this link: >> >>http://www.synclab.org/?tag=raspberry%20pi >> >> Thats an interesting read in and of itself. An additional link is: >> >>http://www.geekroo.com/products/795 >> >> Which is a Mini ITX motherboard for RaspberryPi, which
Re: [time-nuts] Optical Distribution of 1PPS and IRIG
mafl...@theflynn.org said: > I am working on a project where I need to transfer 1PPS approximately 120 > meters between buildings.I cam borrow a pair of 62.5 fibers from IT/ > telco to do so. Google for >fiber IRIG< gets plenty of hits. Raw PPS is a nasty case for fibers. You need some sort of modulation/encoding, or derive it from the IRIG signal. The dynamic range that the receiver in a fiber setup can see is huge. All the modules I've worked with include AGC. That needs a signal to listen to. I haven't seen any with a time-constant slow enough to work with 1 PPS. If I wanted to send a PPS over fiber, I'd probably do something like this: send the PPS using Manchester encoding. that assumes you have a 20 MHz source clock synced to the PPS at the receiver, use a PLL to make a 20 MHz clock, and use that to decode the data The received PPS will be several clock cycles late. You can undo that with with simple digital logic. Just delay it by 20,000,000 - N cycles. Now it's only late by the fiber speed of light delay. (plus various digital prop delays and clock-out delays) -- These are my opinions. I hate spam. ___ 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] time.windows.com statistics
I have set the time server to us.pool.ntp.org. It's keeping my clock in step with the rest of the world so I am a happy camper. I had no idea my simple question would result in such a long thread. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: "Chris Albertson" To: "Discussion of precise time and frequency measurement" Sent: Monday, July 14, 2014 11:00 AM Subject: Re: [time-nuts] time.windows.com statistics On Mon, Jul 14, 2014 at 3:38 AM, Tim Shoppa wrote: Wonder out loud if using NTP server in a load-distributing cloud will just intrinsically be randomly cruddy, or if this is somehow engineering a source which is often good enough for SNTP users but obviously inappropriate for NTP to prevent extra load from non-windows users. Pool servers seem to work well. But they are randomly assigned only once. Once a connection is made to a pool server it remains connected to the same server "for the duration". Best practice is to use about five pool servers and let NTP sort out which are "best". Even if using a GPS you should still configure about five pool servers. A load distributed load cloud where each data packet goes to a different server just plan would not work for NTP. If you look at the clock selection algorithm the servers would all be rejected and NTP would likely fall back to the PC's internal clock as the best source. NTP's design depends on network path between any two NTP servers remaining mostly constant or at least changing slowly. Load sharing would kill that assumption. -- 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] time.windows.com statistics
On Mon, Jul 14, 2014 at 11:10 AM, Kenton A. Hoover < ken...@nemersonhoover.org> wrote: > But a perfectly reasonable source of time for SNTP where you just slam the > clock, rather than NTP where you're figuring out drift... > And if you use pool.ntp.org it doesn't matter and this entire discussion becomes moot. -- Brian Lloyd Lloyd Aviation 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ 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] time.windows.com statistics
But a perfectly reasonable source of time for SNTP where you just slam the clock, rather than NTP where you're figuring out drift... -- Kenton A. Hoover kenton . nemersonhoover org +1 415 830 5843 On 14 July 2014 at 05.:23.14, Tim Shoppa (tsho...@gmail.com) wrote: On the subject of "time.windows.com", it is usually up but it seems to be a pretty cruddy source of NTP time. The actual source is somewhere in the Akamai cloud (so even if it resolves to the same numeric address twice, tha Akamai cloud may in fact be farming it out to geographically different machines) and I often find responses from time.windows.com to be all over the map, with a scatter of 100 milliseconds or more and often timing out, making time.windows.com one of the cruddyist NTP servers out there. Wonder out loud if using NTP server in a load-distributing cloud will just intrinsically be randomly cruddy, or if this is somehow engineering a source which is often good enough for SNTP users but obviously inappropriate for NTP to prevent extra load from non-windows users. Tim N3QE On Sun, Jul 13, 2014 at 5:37 AM, Esa Heikkinen wrote: > Hi! > > At first, Windows XP supports SNTP protocol (so it can be synchronized > with NTP server, but not with "millisecond" grade accuracy) and it uses > time.windows.com as default server. Maybe Microsoft is closed that server > or something, if it doesn't work anymore. However it's easy to change the > NTP server, like Ed Palmer alrady described. > > It's also possible to use local NTP server, I use Symmetricom/Datum > TymServe 2100 to synchronize the system cloks for all Windows computers. > Works fine and does not need connection outside local network. > > Any Windows computer can also act as NTP server, if "millisecond" grade > time is not needed. Registry change is needed to enable the Windows NTP > server, Google if you want to do this. In addition, the system running as > NTP server must also have working NTP client configuration so that it > syncrhonizes itself. But remember, integrated Windows NTP is not very > accurate, the time may have even more than ten seconds offsets. > > > You do not want to have your XP box connected to the internet at all. >> This is not something that can be dealt with by any anti-virus software >> you >> are running. >> > > I even have Windows 2000 computer having 24/7 internet connection. This is > a server computer running 24/7, doing certain tasks. Windows 2000 support > is stopped many years ago and also there's not even anti-virus software > compatible with Windows 2000 anymore. Sounds dangerous? Not necessary - > there has not been any trouble ever... > > The secret is that this (and all other computers) are behind NAT firewall > so there's no direct access to this (or other) Windows computers. Second > thing is (maybe most important), that this computer is NOT used for any web > browsing or e-mails (which are most common way to infect any unprotected > computer). > > By the way, XP support is not fully stopped yet, there's still monthly > malware removal updates coming. Last one happened just few days ago. We > still use XP for work (with anti-virus software of course) and there's > never been any problems with it. Any suspicious traffic from local network > to the Internet will be noticed by network monitoring, but there's haven't > been any. XP is safe, if it's behing network firewall. > > One easy trick to keep any Windows computer safe is to use Jotti's Malware > Scan service before running any new .exe files downloaded from Internet: > > http://virusscan.jotti.org/ > > This is an easy-to use online service, where you can send files for > scanning. It uses more than 20 anti-virus tools to scan the file and > reports the results from each tool. If the file is infected, there will be > many alerts, even when the anti-virus software installed in own computer > doesn't give any alert. > > Connecting any Windows computer directly to the Internet (without NAT or > nework firewall) or DMZ is not recommended at all, even if it has most > recent Windows version. There will be always new and undetected > vulnerabilities. That's the reason why the Windows updates exists. > > -- > 73s! > Esa > OH4KJU > > ___ > 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 an
Re: [time-nuts] time.windows.com statistics
On Mon, Jul 14, 2014 at 3:38 AM, Tim Shoppa wrote: > Wonder out loud if using NTP server in a load-distributing cloud will just > intrinsically be randomly cruddy, or if this is somehow engineering a > source which is often good enough for SNTP users but obviously > inappropriate for NTP to prevent extra load from non-windows users. Pool servers seem to work well. But they are randomly assigned only once. Once a connection is made to a pool server it remains connected to the same server "for the duration". Best practice is to use about five pool servers and let NTP sort out which are "best". Even if using a GPS you should still configure about five pool servers. A load distributed load cloud where each data packet goes to a different server just plan would not work for NTP. If you look at the clock selection algorithm the servers would all be rejected and NTP would likely fall back to the PC's internal clock as the best source. NTP's design depends on network path between any two NTP servers remaining mostly constant or at least changing slowly. Load sharing would kill that assumption. -- 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] time.windows.com statistics
On the subject of "time.windows.com", it is usually up but it seems to be a pretty cruddy source of NTP time. The actual source is somewhere in the Akamai cloud (so even if it resolves to the same numeric address twice, tha Akamai cloud may in fact be farming it out to geographically different machines) and I often find responses from time.windows.com to be all over the map, with a scatter of 100 milliseconds or more and often timing out, making time.windows.com one of the cruddyist NTP servers out there. Wonder out loud if using NTP server in a load-distributing cloud will just intrinsically be randomly cruddy, or if this is somehow engineering a source which is often good enough for SNTP users but obviously inappropriate for NTP to prevent extra load from non-windows users. Tim N3QE On Sun, Jul 13, 2014 at 5:37 AM, Esa Heikkinen wrote: > Hi! > > At first, Windows XP supports SNTP protocol (so it can be synchronized > with NTP server, but not with "millisecond" grade accuracy) and it uses > time.windows.com as default server. Maybe Microsoft is closed that server > or something, if it doesn't work anymore. However it's easy to change the > NTP server, like Ed Palmer alrady described. > > It's also possible to use local NTP server, I use Symmetricom/Datum > TymServe 2100 to synchronize the system cloks for all Windows computers. > Works fine and does not need connection outside local network. > > Any Windows computer can also act as NTP server, if "millisecond" grade > time is not needed. Registry change is needed to enable the Windows NTP > server, Google if you want to do this. In addition, the system running as > NTP server must also have working NTP client configuration so that it > syncrhonizes itself. But remember, integrated Windows NTP is not very > accurate, the time may have even more than ten seconds offsets. > > > You do not want to have your XP box connected to the internet at all. >> This is not something that can be dealt with by any anti-virus software >> you >> are running. >> > > I even have Windows 2000 computer having 24/7 internet connection. This is > a server computer running 24/7, doing certain tasks. Windows 2000 support > is stopped many years ago and also there's not even anti-virus software > compatible with Windows 2000 anymore. Sounds dangerous? Not necessary - > there has not been any trouble ever... > > The secret is that this (and all other computers) are behind NAT firewall > so there's no direct access to this (or other) Windows computers. Second > thing is (maybe most important), that this computer is NOT used for any web > browsing or e-mails (which are most common way to infect any unprotected > computer). > > By the way, XP support is not fully stopped yet, there's still monthly > malware removal updates coming. Last one happened just few days ago. We > still use XP for work (with anti-virus software of course) and there's > never been any problems with it. Any suspicious traffic from local network > to the Internet will be noticed by network monitoring, but there's haven't > been any. XP is safe, if it's behing network firewall. > > One easy trick to keep any Windows computer safe is to use Jotti's Malware > Scan service before running any new .exe files downloaded from Internet: > > http://virusscan.jotti.org/ > > This is an easy-to use online service, where you can send files for > scanning. It uses more than 20 anti-virus tools to scan the file and > reports the results from each tool. If the file is infected, there will be > many alerts, even when the anti-virus software installed in own computer > doesn't give any alert. > > Connecting any Windows computer directly to the Internet (without NAT or > nework firewall) or DMZ is not recommended at all, even if it has most > recent Windows version. There will be always new and undetected > vulnerabilities. That's the reason why the Windows updates exists. > > -- > 73s! > Esa > OH4KJU > > ___ > 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] Setting Windows XP clock.
For your interest, this is what NTP reports when running on a VMware player under Windows 8.1 update 1: http://www.satsignal.eu/mrtg/performance_web-server.php Well with +/- 0.5 milliseconds. This is the host PC which is a Windows stratum-1 server (Sure GPS/PPS synced): http://www.satsignal.eu/mrtg/performance_kiruna.php Within about 100 microseconds. I think the new precise time OS function calls are helping here. 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.
