[ntp:questions] reftime > xmt in server reply valid?

Hi, RFC 5905 has in section 5.1.1.: /* * Verify valid root distance. */ if (r->rootdelay / 2 + r->rootdisp >= MAXDISP || p->reftime > r->xmt) return; /* invalid header values */ But it seems that ntpd (at least 4.2.6p3 and 4.2.7p162) doesn't have the reftime > xmt

Re: [ntp:questions] Assistance with PPS on Windows

Assuming the Delay, Offset, and Jitter column units are msec, after letting it run overnight and half of the next day I still see PPS with 0 delay, 4.559 msec offset, and 3.123 msec jitter. The PPS source is the Meinberg TCR511PCI card, as seen here: http://www.meinberg.de/english/products/tcr511p

Re: [ntp:questions] Assistance with PPS on Windows

The most simple explanation is that the PPS signal out of the clock is just about as poor as NTP is reporting it to be. In other words everything is working fine. Nothing is wrong with your cable or with NTP or with Windows.Until some tests show otherwise I think it is best to assume the PPS

Re: [ntp:questions] Assistance with PPS on Windows

On 2011-05-05, Chris Albertson wrote: > The most simple explanation is that the PPS signal out of the clock is > just about as poor as NTP is reporting it to be. In other words > everything is working fine. Nothing is wrong with your cable or with > NTP or with Windows.Until some tests show

Re: [ntp:questions] Assistance with PPS on Windows

On Thu, May 5, 2011 at 11:46 AM, unruh wrote: >> If you need better buy a GPS.  You can get setup with one that does >> works at the nanosecond level for under $100. > > Uh, no. There is no way of getting the signal into the computer with > nanosecond accuracy. 1usec is about it. You are right.

Re: [ntp:questions] Windows time question.

In article , david- tay...@blueyonder.co.uk.invalid says... > > How critical is your time need? If it's within minutes, then the PC's > clock is likely good enough. If it's in the UK or Europe, I would be > surprised if pool servers did not get you well within the second > perhaps > within 1

Re: [ntp:questions] Windows time question.

In article , un...@wormhole.physics.ubc.ca says... > > On 2011-05-03, David J Taylor wrote: > >> As the OP who started this (long and sometimes ammusing) thread... > >> > >> I do carry a GPS receiver with me, but sadly not PPS capable, I use it > >> for location determination/tracking/navigating

Re: [ntp:questions] Assistance with PPS on Windows

unruh wrote: Uh, no. There is no way of getting the signal into the computer with No pure sw way, no. nanosecond accuracy. 1usec is about it. The interrupt service routines, if you use a specialised driver for some interrupt driven card, will take about 1usec to service the interrupt. Thus wh

Re: [ntp:questions] Assistance with PPS on Windows

On 5/5/2011 3:59 PM, Chris Albertson wrote: On Thu, May 5, 2011 at 11:46 AM, unruh wrote: If you need better buy a GPS. You can get setup with one that does works at the nanosecond level for under $100. Uh, no. There is no way of getting the signal into the computer with nanosecond accuracy

Re: [ntp:questions] Assistance with PPS on Windows

On Thu, May 5, 2011 at 1:13 PM, Terje Mathisen <"terje.mathisen at tmsw.no"@ntp.org> wrote: > unruh wrote: > Add some extra hw, in the form of a very good crystal (surplus Rb) and a hw > counter which starts to run on the PPS signal, so that the sw can query it > to determine how much interrupt la

Re: [ntp:questions] Assistance with PPS on Windows

On Thu, May 5, 2011 at 1:45 PM, Richard B. Gilbert wrote: > Getting the time into the computer takes X microseconds where X depends on > the hardware and software.  Windows' clock ticks every 17 milliseconds or > something like that.  Other operating systems also take a toll! The way it is typic

Re: [ntp:questions] Windows time question.

Not that accurate, within a second for what I need when traveling for work. But I often as not find the last choice of server(s) problematical, for some odd reason. Many hotel internet seems to be tunneled somewhere else, before it gets out to the wider www, with all the hidden latency and filt

Re: [ntp:questions] Windows time question.

Two data line's, plus ground and 5V power. The data lines form a bidirectional diferential data bus, with a protocol more like a network than anything else. For low speed devices, there are bitbanged firmware routines about for the likes of the Atmel single chip devices, if it interests you. ht

Re: [ntp:questions] Assistance with PPS on Windows

"Richard B. Gilbert" wrote in message news:ojmdnuvxob4wkv7qnz2dnuvz_vydn...@giganews.com... [] Getting the time into the computer takes X microseconds where X depends on the hardware and software. Windows' clock ticks every 17 milliseconds or something like that. Other operating systems al

Re: [ntp:questions] Assistance with PPS on Windows

Ken Link wrote: > The PPS source is the Meinberg TCR511PCI card, ... > ... The pins must be different, otherwise the card > wouldn't be able to lock onto the IRIG B signal, right? See: TCR511PCI IRIG Code controlled Radio Clock

Re: [ntp:questions] Assistance with PPS on Windows

unruh wrote: > Uh, no. There is no way of getting the signal into the > computer with nanosecond accuracy. 1usec is about it. > The interrupt service routines, if you use a specialised > driver for some interrupt driven card, will take about > 1usec to service the interrupt. IIRC some BSD varia

Re: [ntp:questions] Windows time question.

David J Taylor wrote: > I'm surprised it's as bad as more than a second out > - but I'll have my portable with me this weekend and > if the hotel has Wi-Fi I'll see what I get if I have > the chance. I've been to some hotels in po-dunk (whatever the colloquial slang is) Europe; Wi-Fi via Sat

Re: [ntp:questions] Assistance with PPS on Windows

BlackLists wrote: > unruh wrote: >> Uh, no. There is no way of getting the signal into the >> computer with nanosecond accuracy. 1usec is about it. >> The interrupt service routines, if you use a specialised >> driver for some interrupt driven card, will take about >> 1usec to service the interr

Re: [ntp:questions] Assistance with PPS on Windows

On 2011-05-05, E-Mail Sent to this address will be added to the BlackLists wrote: > unruh wrote: >> Uh, no. There is no way of getting the signal into the >> computer with nanosecond accuracy. 1usec is about it. >> The interrupt service routines, if you use a specialised >> driver for some inte

Re: [ntp:questions] Assistance with PPS on Windows

On 2011-05-05, Chris Albertson wrote: > On Thu, May 5, 2011 at 1:13 PM, Terje Mathisen <"terje.mathisen at > tmsw.no"@ntp.org> wrote: >> unruh wrote: > >> Add some extra hw, in the form of a very good crystal (surplus Rb) and a hw >> counter which starts to run on the PPS signal, so that the sw ca

[ntp:questions] general questions regarding ntpd on QNX

Hello! I’m usingntpd to synchronize some devices on QNX from one on QNX, synced from TSIP. With some simple app based on libntpq I query ntpd and get somesome status/offsets information. I need offsets to become about millisecondvery fast after start:   tos mindist1.000 tinkerpanic 0 stepo

Re: [ntp:questions] Assistance with PPS on Windows

On Thu, May 5, 2011 at 6:16 PM, unruh wrote: > We are talking about synchronizing the PC clock to GPS to a certain > accuracy. Not measuring time intervals between inputs to a certain accuracy. > The "interupt being serviced" is the problem. The time it takes for an > interrupt service routine to

Re: [ntp:questions] POSIX leap seconds versus the current NTP behaviour

Dave, Yes, that would be me. Long time no talk. POSIX time is also UTC, so that is in accord. Moreover, POSIX "seconds since an epoch" timestamps and NTP "seconds since an epoch" timestamps are "UTC" in exactly the same way, in that they represent a "UTC" timescale where all days are exactly 86

Re: [ntp:questions] Windows time question.

I've been to some hotels in po-dunk (whatever the colloquial slang is) Europe; Wi-Fi via Sat to ISP to internet, over utilized, high latency, really low bandwidth, ... I've had colleagues in the middle of the South American jungle on similar corporate setups at base camps for new oil refinerie

Re: [ntp:questions] Assistance with PPS on Windows

"unruh" wrote in message news:slrnis6idl.eqd.un...@wormhole.physics.ubc.ca... [] IIRC some BSD variants were claiming to get ~<150ns? I do not believe that you can service an interrupt, and read a system clock that quickly. If you have specialised hardware on the PC (as someone suggested, a