Re: [ntp:questions] NTP absolute accuracy?

Unruh wrote in message news:rl5hm.50089$db2.40...@edtnps83... [] As I tried to emphasise, if the round trip is not symmetric, then neither ntp not chrony can compensate for that lack of symmetry, and the absolute time will be out. If occasionally it has an assymetric round trip, then ntp

Re: [ntp:questions] NTP absolute accuracy?

David Lord wrote: How do you get the time difference between your GPS and system time? Include the GPS in your ntp.conf, but mark it with noselect on the server line. ___ questions mailing list questions@lists.ntp.org

Re: [ntp:questions] NTP absolute accuracy?

David Lord sn...@lordynet.org writes: Unruh wrote: David Lord sn...@lordynet.org writes: David J Taylor wrote: Unruh unruh-s...@physics.ubc.ca wrote in message news:qg_gm.50009$db2.46...@edtnps83... David J Taylor david-tay...@blueyonder.not-this-bit.nor-this.co.uk.invalid writes:

[ntp:questions] Frequently asked question about error bounds?

What is the correct error bound between client and server? In the RFC documentation I read one thing and in many theads another. I'm confused so please help me. Which is correct? 1) In the documentation for RFC1305 p. 102 it can be read that the true offset between client and server must lie

Re: [ntp:questions] Frequently asked question about error bounds?

berra.84 wrote: 1) In the documentation for RFC1305 p. 102 it can be read that the true offset between client and server must lie somewhere in the correctness interval, defined by I=[theta - delta/2 - epsilon, theta + delta/2 + epsilon] This is (more) correct. I'm not sure if it fully

Re: [ntp:questions] NTP absolute accuracy?

Unruh unruh-s...@physics.ubc.ca wrote in message news:iebhm.50125$db2.41...@edtnps83... [...] The problem is that I have no idea what the accuracy of any of those items is. YOur ISP's timesever may be a stratum 7 getting time from a bunch of bozos. Or itmay be stratum 1 getting its time from a

Re: [ntp:questions] Frequently asked question about error bounds?

berra.84 berra...@spray.se writes: What is the correct error bound between client and server? In the RFC documentation I read one thing and in many theads another. I'm confused so please help me. Which is correct? 1) In the documentation for RFC1305 p. 102 it can be read that the true offset

Re: [ntp:questions] NTP absolute accuracy?

David J Taylor david-tay...@blueyonder.not-this-bit.nor-this.co.uk.invalid writes: Unruh wrote in message news:iebhm.50125$db2.41...@edtnps83... [] MSF? See: http://www.npl.co.uk/science-technology/time-frequency/time/products-and-services/msf-radio-time-signal UK 60KHz radio time

Re: [ntp:questions] NTP absolute accuracy?

Unruh wrote in message news:vcjhm.50153$db2.9...@edtnps83... [] UK 60KHz radio time signal. Ah, OK. Its accuracy is probably not much better than a few msec I assume. GPS is a few usec. Since the network gives accuracies of better than a few ms, MSF is not a good way of testing the

Re: [ntp:questions] NTP absolute accuracy?

David J Taylor writes: UK 60KHz radio time signal. Bill Unruh writes: Ah, OK. Its accuracy is probably not much better than a few msec I assume. Should be as good as WWVB, which is good to within 100usec. The propagation delay is highly predictable at 60KHz. These stations can also can

Re: [ntp:questions] NTP absolute accuracy?

I wrote: Should be as good as WWVB, which is good to within 100usec. But evidently many commercial receivers are only good to a ms or two. -- John Hasler jhas...@newsguy.com Dancing Horse Hill Elmwood, WI USA ___ questions mailing list

Re: [ntp:questions] Running two ntpd systems in parallel

Please see my message to hackers@ today pointing to a prototype ntpd that disciplines a synthetic clock and does not require root privileges: http://lists.ntp.org/pipermail/hackers/2009-November/004633.html Cheers, Dave Hart ___ questions mailing list

Re: [ntp:questions] NTP absolute accuracy?

I wrote: Should be as good as WWVB, which is good to within 100usec. The David Woolley writes: Most receivers only use the slow code (including the simple hardware solutions for ntpd). I'm assuming a real receiver. With the single-chip designs intended for atomic watches you'll be lucky to

Re: [ntp:questions] NTP absolute accuracy?

David J Taylor david-tay...@blueyonder.not-this-bit.nor-this.co.uk.invalid writes: Unruh wrote in message news:vcjhm.50153$db2.9...@edtnps83... [] UK 60KHz radio time signal. Ah, OK. Its accuracy is probably not much better than a few msec I assume. GPS is a few usec. Since the network

Re: [ntp:questions] NTP absolute accuracy?

Bill Unruh writes: Sorry, at 10usec, the distance away of the transmitter must be less than 3 km. 10usec at the transmitter. Also your system needs to see the start of the tone to 10usec which means that the tone would have to be about 1MHz which is a bit beyond audio. There isn't any tone.

Re: [ntp:questions] NTP absolute accuracy?

John Hasler jhas...@newsguy.com writes: Bill Unruh writes: Sorry, at 10usec, the distance away of the transmitter must be less than 3 km. 10usec at the transmitter. Also your system needs to see the start of the tone to 10usec which means that the tone would have to be about 1MHz which is

Re: [ntp:questions] NTP absolute accuracy?

Unruh wrote: John Haslerjhas...@newsguy.com writes: There isn't any tone. It's the UK equivalent of WWVB. How is the beginning of the second ( an hour) marked? The bandwidth of whatever marks it has to be pretty narrow, or the transmitter would interfer with everything around it. Ie, that