Re: [time-nuts] Discipline an oscillator with NTP?

Interesting did go to the site and the library. They mention using the GPS 1pps as a reference for tuning as we discussed earlier. Also the expected jitter and performance mentioned by others on this thread. So indeed, I do not see that the NTP solution is better then 1^-6 or 7th ppm and it does h

Re: [time-nuts] Discipline an oscillator with NTP?

On Sat, Jul 23, 2011 at 8:17 PM, Don Latham wrote: > So, I essentially want to feed ntpd and its MSoft equivalents. > > I found the www.ntp.net site, that apparently has open software to do Use instead. You can also look at the Public NTP pool project,

Re: [time-nuts] Discipline an oscillator with NTP?

Hi The standard NTP software does a "best of the bunch" selection when given a large number of servers. What it considers best and what you would pick likely are not the same thing. You stick at a few ms of error rather than getting say a 10X improvement with 100 servers. Custom code, custom h

Re: [time-nuts] Discipline an oscillator with NTP?

Indeed thats why I was saying choose 3 servers. Now I see in the thread that you can pick pools of servers so thats good. Then average what they say the time is and drive oscillator. Wonder if you could look towards the stratum 1 servers. But that said I could easily believe that it might ot be

Re: [time-nuts] Discipline an oscillator with NTP?

OK, Steve and Bjorn. I will have to get busy and see what I can do. Thanks very much for your input. Don Steve Longcor > ntpd is both a client (getting time info from other ntp servers) and a > server (responding to requests from other clients on the network.) > Access to the server part is contro

Re: [time-nuts] Discipline an oscillator with NTP?

ntpd acts at the same time as a server and as a client, it is included with all linux distiributions and also FreeBSD and other BSDs. Meinberg has a pre-compiled ntp for Windows. The Windows Time Service included in windows xp and 7 is a particular interpretation of microsoft of any standard (n

Re: [time-nuts] Discipline an oscillator with NTP?

ntpd is both a client (getting time info from other ntp servers) and a server (responding to requests from other clients on the network.) Access to the server part is controlled by firewall rules and "restrict" lines in the ntp.conf file (see example below). An explanation of these can be fou

Re: [time-nuts] Discipline an oscillator with NTP?

Hi Don, ntpd is both server and client. For a ublox with usb i did the following a few days ago. sudo ln -s /dev/ttyACM0 /dev/gps0 add this to the /etc/ntp.conf server 127.127.20.0 mode 81 and then /etc/init.d/ntp restart This particular setup without 1pps gives a lousy time (

Re: [time-nuts] Discipline an oscillator with NTP?

> ntpd is the server. > Scott: OK. Here's what I get from man ntpd: "The ntpd program is an operating system daemon which sets and maintains the system time of day in synchronism with Internet standard time servers." What I want to do is build a little local net only "standard time server" The

Re: [time-nuts] Discipline an oscillator with NTP?

At 06:45 PM 7/23/2011, Don Latham wrote: than a client. I looked up man ntpd, and it seems at first glance to be a Linux/Unix client that will sync up a local computer. I want to generate a network server that ntpd or other clients can access. Perhaps ntpd is the server. -- newell N5TNL _

Re: [time-nuts] Discipline an oscillator with NTP?

Hi Bjorn: Thanks very much for the sources! I was afraid I was not clear when I sent my question(s). I want to generate a network server rather than a client. I looked up man ntpd, and it seems at first glance to be a Linux/Unix client that will sync up a local computer. I want to generate a networ

Re: [time-nuts] Discipline an oscillator with NTP?

Hi Don, 1PPS is useful. 10MHz is not direcly useful. You also need some kind of timecode, telling ntpd which second the 1pps indicated. The software side is normally ntpd configured with one of its drivers (called refclock) for the GPS protocol your receiver has. Again the most used is probably r

Re: [time-nuts] Discipline an oscillator with NTP?

Poul and others? As usual, I suddenly had a thought ripple across my otherwise placid cortex, and have forgotten if there was a previous answer on this thread. What does a NTP server look like on the network? There are now several small net appliances/eval boards available. I run a program called N

Re: [time-nuts] Discipline an oscillator with NTP?

In message <022101cc4970$b24a4b80$16dee280$@com>, "Jose Camara" writes: >After >one year of NTP queries, assume you have a 100ms jitter on the network time, >you could at most tweak your oscillator, based on past performance, to 6E-9. It is a lot more complicated than that, we need to talk allan-

Re: [time-nuts] Discipline an oscillator with NTP?

In message , Chris Albertson writes: >On Sat, Jul 23, 2011 at 10:40 AM, Bob Camp wrote: >NTP's clock selection algorithm is pretty good. If you choose a >diverse set of servers then NTP will only use the subset of them that >are self consistent. That depends a lot on your definition of "good".

Re: [time-nuts] Discipline an oscillator with NTP?

:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, July 23, 2011 11:18 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Discipline an oscillator with NTP? Hi WWV "as transmitted" is massively more accurate than it is as received. There

Re: [time-nuts] Discipline an oscillator with NTP?

Indeed thats why I was saying choose 3 servers. Now I see in the thread that you can pick pools of servers so thats good. Then average what they say the time is and drive oscillator. Wonder if you could look towards the stratum 1 servers. But that said I could easily believe that it might ot be any

Re: [time-nuts] Discipline an oscillator with NTP?

Hi WWV "as transmitted" is massively more accurate than it is as received. There are a lot of NTP servers out there with offsets in the ms to fraction of a ms range. Even if your path was perfect, those issues would keep you from getting to the us level. You could indeed build up some custom se

Re: [time-nuts] Discipline an oscillator with NTP?

On Sat, Jul 23, 2011 at 10:40 AM, Bob Camp wrote: > There's also the basic "do I trust the server" issue. You can indeed trust > WWV as transmitted. NTP's clock selection algorithm is pretty good. If you choose a diverse set of servers then NTP will only use the subset of them that are self c

Re: [time-nuts] Discipline an oscillator with NTP?

Hi Same issue with NTP. As long as you aren't on a link with nasty asymmetry problems or highly variable delays. There's also the basic "do I trust the server" issue. You can indeed trust WWV as transmitted. Bob On Jul 23, 2011, at 1:24 PM, Jim Lux wrote: > On 7/23/11 9:42 AM, Bob Camp wrote

Re: [time-nuts] Discipline an oscillator with NTP?

On 7/23/11 9:42 AM, Bob Camp wrote: Hi The simple answer is that normal NTP via the net will give you accuracy similar to the "zero beat to WWV" approach. It will take a few days to get to that level. Much faster to fire up the radio and use WWV. Bob If you aren't somewhere that has no rad

Re: [time-nuts] Discipline an oscillator with NTP?

Hi There is a range in what NTP will do, just as there is a range in what you can do via zero beat to WWV. You can get to a ppm or so via zero beat most of the time. Under good conditions you can get to 0.1 ppm. A practial NTP system running to servers over the net has roughly the same accuracy

Re: [time-nuts] Discipline an oscillator with NTP?

Yes but zero beat by ear is terrible. Are you talking a scope and I think thats only 1 X 10-7 as I recall. Regards Paul. On Sat, Jul 23, 2011 at 12:42 PM, Bob Camp wrote: > Hi > > The simple answer is that normal NTP via the net will give you accuracy > similar to the "zero beat to WWV" approach

Re: [time-nuts] Discipline an oscillator with NTP?

Hi The simple answer is that normal NTP via the net will give you accuracy similar to the "zero beat to WWV" approach. It will take a few days to get to that level. Much faster to fire up the radio and use WWV. Bob On Jul 23, 2011, at 12:29 PM, paul swed wrote: > I may be reading way to much

Re: [time-nuts] Discipline an oscillator with NTP?

I may be reading way to much into the question. But the goal discipline the local oscillator as an alternate to GPS or WWVB etc Further assumption get the same types of services out of the oscillator Frequency and time plus pulses. That said if its one ntp source you look at, potentially far down

Re: [time-nuts] Discipline an oscillator with NTP?

July 2011 7:28 PM To: time-nuts@febo.com Subject: [time-nuts] Discipline an oscillator with NTP? I was just thinking (dangerous I know)... Has anyone attempted to build a stand-alone oscillator that is disciplined via NTP? i.e. NTP keeps it on-frequency... And I'm not talking about NTP that is l

Re: [time-nuts] Discipline an oscillator with NTP?

First, catch your rabbit... Jim Lux > On 7/22/11 3:46 PM, brent evers wrote: >> "After that all you need to do is write some code to..." >> >> Oh - if I had a nickel for every time I've heard that! >> >> Brent >> > > When I worked in the physical effects business, we'd get a set of > storyboards f

Re: [time-nuts] Discipline an oscillator with NTP?

Yes but in this case it really is easy; Below is an outline (don't try to compile it.). It has a slight problem because just using "sleep" is kind of simplistic. One should wait on the new second and add some error chacking Point here is just to show that this is not weeks and weeks worth of

Re: [time-nuts] Discipline an oscillator with NTP?

On 7/22/11 3:46 PM, brent evers wrote: "After that all you need to do is write some code to..." Oh - if I had a nickel for every time I've heard that! Brent When I worked in the physical effects business, we'd get a set of storyboards from a director, and we'd have to figure out how we were

Re: [time-nuts] Discipline an oscillator with NTP?

On Fri, Jul 22, 2011 at 2:30 PM, Javier Herrero wrote: > I've found a plot of the ntp-synthesized GPS output compared with the > UTC-aligned GPS from a Thunderbolt. The generated PPS output was 1us wide, > and it is represented in infinite persistence to get an idea of the jitter. > The offset was

Re: [time-nuts] Discipline an oscillator with NTP?

On 07/23/2011 12:07 AM, Bob Camp wrote: Hi The easy way is to take a pps off of your external oscillator and feed that into a port on your NTP server. Let NTP tell you where that pps is. Don't let NTP lock to the pps, just let it report it's position. After that all you need to do is write so

Re: [time-nuts] Discipline an oscillator with NTP?

On Fri, 22 Jul 2011 13:27:34 -0500 "Jason Rabel" wrote: > I was just thinking (dangerous I know)... Has anyone attempted to > build a stand-alone oscillator that is disciplined via NTP? > > i.e. NTP keeps it on-frequency... And I'm not talking about NTP that is > locked to a local GPS, I'm curio

Re: [time-nuts] Discipline an oscillator with NTP?

"After that all you need to do is write some code to..." Oh - if I had a nickel for every time I've heard that! Brent On Fri, Jul 22, 2011 at 6:07 PM, Bob Camp wrote: > Hi > > The easy way is to take a pps off of your external oscillator and feed that > into a port on your NTP server. Let NTP

Re: [time-nuts] Discipline an oscillator with NTP?

Hi The easy way is to take a pps off of your external oscillator and feed that into a port on your NTP server. Let NTP tell you where that pps is. Don't let NTP lock to the pps, just let it report it's position. After that all you need to do is write some code to read the location of the pulse

Re: [time-nuts] Discipline an oscillator with NTP?

On Fri, Jul 22, 2011 at 2:48 PM, Javier Herrero wrote: > El 22/07/2011 20:39, michael taylor escribió: >> >> >> I think all NTP server appliances have this functionality by their >> nature, whether or not the oscillator is of particular high quality >> (low noise) or not. Many of the low-end ones

Re: [time-nuts] Discipline an oscillator with NTP?

This is exactly what an NTP server does. It adjusts the rate of a local clock so that the local clock advances at the same rate is the set of Internet servers that have passed a clock selection test. NTP does this very well considering the uncertainly of the lag over the internet. There is a g

Re: [time-nuts] Discipline an oscillator with NTP?

On 7/22/11 11:59 AM, Chuck Forsberg WA7KGX N2469R wrote: On 07/22/2011 11:48 AM, Javier Herrero wrote: El 22/07/2011 20:39, michael taylor escribió: I think all NTP server appliances have this functionality by their nature, whether or not the oscillator is of particular high quality (low nois

Re: [time-nuts] Discipline an oscillator with NTP?

On 07/22/2011 11:48 AM, Javier Herrero wrote: El 22/07/2011 20:39, michael taylor escribió: I think all NTP server appliances have this functionality by their nature, whether or not the oscillator is of particular high quality (low noise) or not. Many of the low-end ones likely just use a stan

Re: [time-nuts] Discipline an oscillator with NTP?

El 22/07/2011 20:39, michael taylor escribió: I think all NTP server appliances have this functionality by their nature, whether or not the oscillator is of particular high quality (low noise) or not. Many of the low-end ones likely just use a standard oscillator "in a can" [2] that the embedde

Re: [time-nuts] Discipline an oscillator with NTP?

No exactly. A PPS generator syncrhonized with UTC time, using a GPS ntp server in the same LAN. Not too bad... but several microseconds jittery :) enough for my application then. Probably with long time constants it is doable, but if the ntp server is in the internet, and not in a LAN, I suspec

Re: [time-nuts] Discipline an oscillator with NTP?

I must say Jason, Yes, you are day dreaming, but hey, that is where ideas come from. I do not play with NTP, but isn't that the same thing ( or similar) as disciplining my local clock when I have it update against a reference like NIST over the Internet ? In other words, NTP is used to keep th

Re: [time-nuts] Discipline an oscillator with NTP?

On Fri, Jul 22, 2011 at 2:27 PM, Jason Rabel wrote: > I was just thinking (dangerous I know)... Has anyone attempted to build a > stand-alone oscillator that is disciplined via NTP? I believe the Symmetricom NTP servers do this, whether or not they have external access to the oscillator or not I

[time-nuts] Discipline an oscillator with NTP?

I was just thinking (dangerous I know)... Has anyone attempted to build a stand-alone oscillator that is disciplined via NTP? i.e. NTP keeps it on-frequency... And I'm not talking about NTP that is locked to a local GPS, I'm curious about purely syncing to other NTP servers over a network. (The