paul chaofu.c...@gmail.com writes:
Hi All, I'm new to NTP, glad to meet you here.
I did some experiments to test NTP performance on WINNT. In an
isolated network, two machines are inter connnected with a switcher.
Machine A is configure as a stratum 12 NTP server, using lcl as
reference
David Woolley wrote:
Unruh wrote:
You can absolutely count on ntpq to tell you what ntp thinks the offset
is based on its querying of the servers or refclocks. What makes you
not so sure.
I don't think he wants the NTP offset metric; I think he wants the
difference between software
David Woolley wrote:
Steve Kostecke wrote:
I'm just not so sure if I can absolutely count on ntpq to determine
time offset of NTP synced machines...
ntpq does not calculate anything. It merely displays information
returned from the ntpd it is querying.
I believe that he means the
Steve Kostecke wrote:
I'm just not so sure if I can absolutely count on ntpq to determine
time offset of NTP synced machines...
ntpq does not calculate anything. It merely displays information
returned from the ntpd it is querying.
I believe that he means the combination of ntpq and and
David Woolley da...@ex.djwhome.demon.co.uk.invalid writes:
Unruh wrote:
You can absolutely count on ntpq to tell you what ntp thinks the offset
is based on its querying of the servers or refclocks. What makes you
not so sure.
I don't think he wants the NTP offset metric; I think he wants
David Woolley da...@ex.djwhome.demon.co.uk.invalid writes:
Steve Kostecke wrote:
I'm just not so sure if I can absolutely count on ntpq to determine
time offset of NTP synced machines...
ntpq does not calculate anything. It merely displays information
returned from the ntpd it is querying.
Unruh wrote:
In other words, there is a random noise component to the software clock
time and to the measurement of UTC via the net, or whatever, and that
In the estimate of the time on the servers and peers. There will also
be an error term from reading the local clock, but it ought to be
David Woolley da...@ex.djwhome.demon.co.uk.invalid writes:
Unruh wrote:
In other words, there is a random noise component to the software clock
time and to the measurement of UTC via the net, or whatever, and that
In the estimate of the time on the servers and peers. There will also
be an
On Jul 26, 12:30 am, David J Taylor david-tay...@blueyonder.not-
this-part.nor-this.co.uk.invalid wrote:
paul wrote:
[]
Thanks, but I mean something which do not rely on the output of
ntpq.exe.
My NTP Monitor uses NTP network calls to determine the offset of the PCs -
it doesn't use
Although you might be able to drive a real (non-USB) parallel port, from
application code, with fairly low latency the results would only be
meaningful for a very unloaded machine, as, on a loaded machine, you
wouldn't really know where you where in the system tick interval, when
you read the
paul wrote:
On Jul 26, 12:30 am, David J Taylor david-tay...@blueyonder.not-
[]
What problem are you trying to solve, and how accurately do you need
to measure?
I'm just not so sure if I can absolutely count on ntpq to determine
time offset of NTP synced machines...
Good question, which I
paul chaofu.c...@gmail.com writes:
On Jul 26, 12:30=A0am, David J Taylor david-tay...@blueyonder.not-
this-part.nor-this.co.uk.invalid wrote:
paul wrote:
[]
Thanks, but I mean something which do not rely on the output of
ntpq.exe.
My NTP Monitor uses NTP network calls to determine the
Unruh wrote:
You can absolutely count on ntpq to tell you what ntp thinks the offset
is based on its querying of the servers or refclocks. What makes you
not so sure.
I don't think he wants the NTP offset metric; I think he wants the
difference between software clock time and true UTC.
On 2009-07-26, paul chaofu.c...@gmail.com wrote:
On Jul 26, 12:30 am, David J Taylor david-tay...@blueyonder.co.uk
wrote:
What problem are you trying to solve, and how accurately do you need
to measure?
I'm just not so sure if I can absolutely count on ntpq to determine
time offset of NTP
On Jul 21, 1:55 pm, David J Taylor david-tay...@blueyonder.not-this-
part.nor-this.co.uk.invalid wrote:
paul wrote:
[]
10 Windows boxes with offset no greater than 5 ms from abs time is
fair enough for me. I will try a local stratum-1 NTP server.
Cheers,
Paul
Paul,
Just for
paul wrote:
[]
Hi David, I am wondering is there any other means to profile NTP
performance, like some kind of hardware setup to measure time offset
of two machine?
I wrote some simple programs which you can download here:
http://www.satsignal.eu/software/net.htm#NTPmonitor
It's
On Jul 25, 11:38 pm, David J Taylor david-tay...@blueyonder.not-
this-part.nor-this.co.uk.invalid wrote:
paul wrote:
[]
Hi David, I am wondering is there any other means to profile NTP
performance, like some kind of hardware setup to measure time offset
of two machine?
I wrote some
paul wrote:
[]
Thanks, but I mean something which do not rely on the output of
ntpq.exe.
My NTP Monitor uses NTP network calls to determine the offset of the PCs -
it doesn't use ntpq. However, in that sense, it does rely on the output
from NTP.
What problem are you trying to solve, and how
paul wrote:
Hi David, I am wondering is there any other means to profile NTP
performance, like some kind of hardware setup to measure time offset
of two machine?
You need access to the source code of the clock interrupt service
routine and the ability to directly right to something like a
David J Taylor david-tay...@blueyonder.not-this-part.nor-this.co.uk.invalid
writes:
paul wrote:
[]
Thanks, but I mean something which do not rely on the output of
ntpq.exe.
You can get say a gps with PPS and attach it to say the parallel port of
your machine, writing and intrrupt service
Unruh wrote:
David J Taylor
[]
For me, a few milliseconds is good enough, but I always want to do
better
a) Don't run Windows.
b) Don't run Windows.
c) I get roughly 2us accuracy. That is about 1000 times better that
you desire. (again a Garmin 18 LVC receiver with PPS running onto my
paul wrote:
[]
10 Windows boxes with offset no greater than 5 ms from abs time is
fair enough for me. I will try a local stratum-1 NTP server.
Cheers,
Paul
Paul,
Just for interest, the ntpd.conf for my PC Narvik contains lines like:
___
server
Hi All, I'm new to NTP, glad to meet you here.
I did some experiments to test NTP performance on WINNT. In an
isolated network, two machines are inter connnected with a switcher.
Machine A is configure as a stratum 12 NTP server, using lcl as
reference clock; machine B is sychronized to machine
paul wrote:
Hi All, I'm new to NTP, glad to meet you here.
I did some experiments to test NTP performance on WINNT. In an
isolated network, two machines are inter connnected with a switcher.
Machine A is configure as a stratum 12 NTP server, using lcl as
reference clock; machine B is
On Jul 20, 10:36 pm, David J Taylor david-tay...@blueyonder.not-
this-part.nor-this.co.uk.invalid wrote:
paul wrote:
Hi All, I'm new to NTP, glad to meet you here.
I did some experiments to test NTP performance on WINNT. In an
isolated network, two machines are inter connnected with a
paul wrote:
[]
Thank you, David.
In my situation, no GPS is availiable. So can I expect better
performance when GPS is used as reference clock, or when a stratum-1
NTP server is added to the network?
Local GPS or a local stratum-1 server will make a significant difference.
When using the
paul wrote:
On Jul 20, 10:36 pm, David J Taylor david-tay...@blueyonder.not-
this-part.nor-this.co.uk.invalid wrote:
paul wrote:
Hi All, I'm new to NTP, glad to meet you here.
I did some experiments to test NTP performance on WINNT. In an
isolated network, two machines are inter connnected
David J Taylor wrote:
[]
And, I noticed the offset for Narvik is more stable than that for
Hydra, is it due the PPS feeded to Narvik? But Bacchus is doing good
too without PPS, Why?
Correction:
Hydra is running Windows-7. Because Windows Vista and Windows-7 may
have a 1KHz clock, the
Richard B. Gilbert wrote:
[]
Assuming a GPS *TIMING* receiver, and that it can be installed with
the antenna having a good view of MOST of the sky, you can expect
results that are *almost* as good as the atomic clocks on board the
satellites!
You do need to run a site survey to establish your
David J Taylor wrote:
Richard B. Gilbert wrote:
[]
Assuming a GPS *TIMING* receiver, and that it can be installed with
the antenna having a good view of MOST of the sky, you can expect
results that are *almost* as good as the atomic clocks on board the
satellites!
You do need to run a site
On Mon, Jul 20, 2009 at 1:57 PM, paul wrote:
Hi All, I'm new to NTP, glad to meet you here.
I did some experiments to test NTP performance on WINNT.
[...]
The OS is Windows XP Pro SP3 and NTP software is 4.2.4-p7 from
mainberg.
Richard B. Gilbert wrote:
[]
That is what a site survey is. The GPS determines its location a
few hundreds of times over the course of a day and does a least
squares calculation to get a reasonable approximation of your
latitude and longitude.
Cellular phone base stations do a more extended
Richard B. Gilbert rgilber...@comcast.net writes:
David J Taylor wrote:
Richard B. Gilbert wrote:
[]
Assuming a GPS *TIMING* receiver, and that it can be installed with
the antenna having a good view of MOST of the sky, you can expect
results that are *almost* as good as the atomic clocks on
David J Taylor david-tay...@blueyonder.not-this-part.nor-this.co.uk.invalid
writes:
Richard B. Gilbert wrote:
[]
That is what a site survey is. The GPS determines its location a
few hundreds of times over the course of a day and does a least
squares calculation to get a reasonable
Unruh wrote:
Richard B. Gilbert rgilber...@comcast.net writes:
David J Taylor wrote:
Richard B. Gilbert wrote:
[]
Assuming a GPS *TIMING* receiver, and that it can be installed with
the antenna having a good view of MOST of the sky, you can expect
results that are *almost* as good as the
On Jul 20, 11:45 pm, David J Taylor david-tay...@blueyonder.not-
this-part.nor-this.co.uk.invalid wrote:
paul wrote:
[]
Thank you, David.
In my situation, no GPS is availiable. So can I expect better
performance when GPS is used as reference clock, or when a stratum-1
NTP server is
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