Empathy List Archives

MB

Miguel Barbosa Gonçalves

Wed, May 15, 2013 12:30 AM

Hi!

I am trying to figure out why NTP takes so long to react to oscillator
changes... I want it to track the PPS from a Trimble Acutime as closely
as possible.

When checking ntptime on startup I see that the NTP daemon is using
PLL and starts the adjustment interval at 8 s. It then increases to
16, 32, 64, 128 and stops at 256.

I read in the documentation that this limit should be 128 but is now 256.

--- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm ---
intervals 57 says that there were 57 calibration intervals. When PPS
pulses are arriving, this number should increase. Each frequency
adjustment requires a good calibration interval. The length of the
current calibration interval can be found as interval 128 s (128
seconds is the default maximum length). Remaining numbers count
abnormal conditions as explained below.
--- end ---

How can I make it stop earlier? At 64 s for example?

Any ideas?

TIA,
Miguel

Hi! I am trying to figure out why NTP takes so long to react to oscillator changes... I want it to track the PPS from a Trimble Acutime as closely as possible. When checking ntptime on startup I see that the NTP daemon is using PLL and starts the adjustment interval at 8 s. It then increases to 16, 32, 64, 128 and stops at 256. I read in the documentation that this limit should be 128 but is now 256. --- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm --- intervals 57 says that there were 57 calibration intervals. When PPS pulses are arriving, this number should increase. Each frequency adjustment requires a good calibration interval. The length of the current calibration interval can be found as interval 128 s (128 seconds is the default maximum length). Remaining numbers count abnormal conditions as explained below. --- end --- How can I make it stop earlier? At 64 s for example? Any ideas? TIA, Miguel

MC

Mark C. Stephens

Wed, May 15, 2013 12:47 AM

You might find that questions@lists.ntp.org is a better place to ask.
Personally, I find the palisade driver breaks a whole lot of stuff when compiled in.
And I suspect the palisade refclock driver is no longer maintained.
I have better results using the ripencc driver for palisade varients.

mark

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Miguel Barbosa Gonçalves
Sent: Wednesday, 15 May 2013 10:31 AM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] NTP, PPS and < 10 us offsets

Hi!

I am trying to figure out why NTP takes so long to react to oscillator changes... I want it to track the PPS from a Trimble Acutime as closely as possible.

When checking ntptime on startup I see that the NTP daemon is using PLL and starts the adjustment interval at 8 s. It then increases to 16, 32, 64, 128 and stops at 256.

I read in the documentation that this limit should be 128 but is now 256.

--- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm --- intervals 57 says that there were 57 calibration intervals. When PPS pulses are arriving, this number should increase. Each frequency adjustment requires a good calibration interval. The length of the current calibration interval can be found as interval 128 s (128 seconds is the default maximum length). Remaining numbers count abnormal conditions as explained below.
--- end ---

How can I make it stop earlier? At 64 s for example?

Any ideas?

TIA,
Miguel

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.

You might find that questions@lists.ntp.org is a better place to ask. Personally, I find the palisade driver breaks a whole lot of stuff when compiled in. And I suspect the palisade refclock driver is no longer maintained. I have better results using the ripencc driver for palisade varients. mark -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Miguel Barbosa Gonçalves Sent: Wednesday, 15 May 2013 10:31 AM To: Discussion of precise time and frequency measurement Subject: [time-nuts] NTP, PPS and < 10 us offsets Hi! I am trying to figure out why NTP takes so long to react to oscillator changes... I want it to track the PPS from a Trimble Acutime as closely as possible. When checking ntptime on startup I see that the NTP daemon is using PLL and starts the adjustment interval at 8 s. It then increases to 16, 32, 64, 128 and stops at 256. I read in the documentation that this limit should be 128 but is now 256. --- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm --- intervals 57 says that there were 57 calibration intervals. When PPS pulses are arriving, this number should increase. Each frequency adjustment requires a good calibration interval. The length of the current calibration interval can be found as interval 128 s (128 seconds is the default maximum length). Remaining numbers count abnormal conditions as explained below. --- end --- How can I make it stop earlier? At 64 s for example? Any ideas? TIA, Miguel _______________________________________________ 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.

CA

Chris Albertson

Wed, May 15, 2013 12:55 AM

Long intervals are a good thing.

What NTP does is discipline the rate of the clock. So lets say you
wanted to adjust the rate of some mechanical clock. You first set it
as good as you can then wait an hour and see if it gained or lost
time. then you move the fast/slow lever on the back of the clock.
After a few hours the clock is pletty good and you have to wait a full
day to see an error. Then as you zero in on the exact rate setting it
takes a week to see any error.

This is kind of what NTP is doing if you want to correct out tiny
errors in the clock rate you have to wait a long time

That said I think there is a "maxpoll" parameter you can add o the
/etc/conf file.

But why?

Maybe not you, but I think some people think "Oh my, NTP is not
checking the time very often. It must not be accurate." That is
thinking backwards, you need the long poll interval to see small
errors in rate. But this assumes a stable local clock. NTP balances
this.

On Tue, May 14, 2013 at 5:30 PM, Miguel Barbosa Gonçalves m@mbg.pt wrote:

Hi!

I am trying to figure out why NTP takes so long to react to oscillator
changes... I want it to track the PPS from a Trimble Acutime as closely
as possible.

When checking ntptime on startup I see that the NTP daemon is using
PLL and starts the adjustment interval at 8 s. It then increases to
16, 32, 64, 128 and stops at 256.

I read in the documentation that this limit should be 128 but is now 256.

--- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm ---
intervals 57 says that there were 57 calibration intervals. When PPS
pulses are arriving, this number should increase. Each frequency
adjustment requires a good calibration interval. The length of the
current calibration interval can be found as interval 128 s (128
seconds is the default maximum length). Remaining numbers count
abnormal conditions as explained below.
--- end ---

How can I make it stop earlier? At 64 s for example?

Any ideas?

TIA,
Miguel

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.

--

Chris Albertson
Redondo Beach, California

Long intervals are a good thing. What NTP does is discipline the rate of the clock. So lets say you wanted to adjust the rate of some mechanical clock. You first set it as good as you can then wait an hour and see if it gained or lost time. then you move the fast/slow lever on the back of the clock. After a few hours the clock is pletty good and you have to wait a full day to see an error. Then as you zero in on the exact rate setting it takes a week to see any error. This is kind of what NTP is doing if you want to correct out tiny errors in the clock rate you have to wait a long time That said I think there is a "maxpoll" parameter you can add o the /etc/conf file. But why? Maybe not you, but I think some people think "Oh my, NTP is not checking the time very often. It must not be accurate." That is thinking backwards, you need the long poll interval to see small errors in rate. But this assumes a stable local clock. NTP balances this. On Tue, May 14, 2013 at 5:30 PM, Miguel Barbosa Gonçalves <m@mbg.pt> wrote: > Hi! > > I am trying to figure out why NTP takes so long to react to oscillator > changes... I want it to track the PPS from a Trimble Acutime as closely > as possible. > > When checking ntptime on startup I see that the NTP daemon is using > PLL and starts the adjustment interval at 8 s. It then increases to > 16, 32, 64, 128 and stops at 256. > > I read in the documentation that this limit should be 128 but is now 256. > > --- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm --- > intervals 57 says that there were 57 calibration intervals. When PPS > pulses are arriving, this number should increase. Each frequency > adjustment requires a good calibration interval. The length of the > current calibration interval can be found as interval 128 s (128 > seconds is the default maximum length). Remaining numbers count > abnormal conditions as explained below. > --- end --- > > How can I make it stop earlier? At 64 s for example? > > Any ideas? > > TIA, > Miguel > _______________________________________________ > 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. -- Chris Albertson Redondo Beach, California

CA

Chris Albertson

Wed, May 15, 2013 12:59 AM

Sorry forgot to include this, read section 5.1.3.3 it descibes how to
min/max poll are used
http://www.ntp.org/ntpfaq/NTP-s-algo.htm#Q-ALGO-CLK-UPD

On Tue, May 14, 2013 at 5:55 PM, Chris Albertson
albertson.chris@gmail.comwrote:

Long intervals are a good thing.

What NTP does is discipline the rate of the clock. So lets say you
wanted to adjust the rate of some mechanical clock. You first set it
as good as you can then wait an hour and see if it gained or lost
time. then you move the fast/slow lever on the back of the clock.
After a few hours the clock is pletty good and you have to wait a full
day to see an error. Then as you zero in on the exact rate setting it
takes a week to see any error.

This is kind of what NTP is doing if you want to correct out tiny
errors in the clock rate you have to wait a long time

That said I think there is a "maxpoll" parameter you can add o the
/etc/conf file.

But why?

Maybe not you, but I think some people think "Oh my, NTP is not
checking the time very often. It must not be accurate." That is
thinking backwards, you need the long poll interval to see small
errors in rate. But this assumes a stable local clock. NTP balances
this.

On Tue, May 14, 2013 at 5:30 PM, Miguel Barbosa Gonçalves m@mbg.pt
wrote:

Hi!

I am trying to figure out why NTP takes so long to react to oscillator
changes... I want it to track the PPS from a Trimble Acutime as closely
as possible.

When checking ntptime on startup I see that the NTP daemon is using
PLL and starts the adjustment interval at 8 s. It then increases to
16, 32, 64, 128 and stops at 256.

I read in the documentation that this limit should be 128 but is now 256.

--- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm ---
intervals 57 says that there were 57 calibration intervals. When PPS
pulses are arriving, this number should increase. Each frequency
adjustment requires a good calibration interval. The length of the
current calibration interval can be found as interval 128 s (128
seconds is the default maximum length). Remaining numbers count
abnormal conditions as explained below.
--- end ---

How can I make it stop earlier? At 64 s for example?

Any ideas?

TIA,
Miguel

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.

--

Chris Albertson
Redondo Beach, California

--

Chris Albertson
Redondo Beach, California

Sorry forgot to include this, read section 5.1.3.3 it descibes how to min/max poll are used http://www.ntp.org/ntpfaq/NTP-s-algo.htm#Q-ALGO-CLK-UPD On Tue, May 14, 2013 at 5:55 PM, Chris Albertson <albertson.chris@gmail.com>wrote: > Long intervals are a good thing. > > What NTP does is discipline the rate of the clock. So lets say you > wanted to adjust the rate of some mechanical clock. You first set it > as good as you can then wait an hour and see if it gained or lost > time. then you move the fast/slow lever on the back of the clock. > After a few hours the clock is pletty good and you have to wait a full > day to see an error. Then as you zero in on the exact rate setting it > takes a week to see any error. > > This is kind of what NTP is doing if you want to correct out tiny > errors in the clock rate you have to wait a long time > > That said I think there is a "maxpoll" parameter you can add o the > /etc/conf file. > > But why? > > Maybe not you, but I think some people think "Oh my, NTP is not > checking the time very often. It must not be accurate." That is > thinking backwards, you need the long poll interval to see small > errors in rate. But this assumes a stable local clock. NTP balances > this. > > > > On Tue, May 14, 2013 at 5:30 PM, Miguel Barbosa Gonçalves <m@mbg.pt> > wrote: > > Hi! > > > > I am trying to figure out why NTP takes so long to react to oscillator > > changes... I want it to track the PPS from a Trimble Acutime as closely > > as possible. > > > > When checking ntptime on startup I see that the NTP daemon is using > > PLL and starts the adjustment interval at 8 s. It then increases to > > 16, 32, 64, 128 and stops at 256. > > > > I read in the documentation that this limit should be 128 but is now 256. > > > > --- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm --- > > intervals 57 says that there were 57 calibration intervals. When PPS > > pulses are arriving, this number should increase. Each frequency > > adjustment requires a good calibration interval. The length of the > > current calibration interval can be found as interval 128 s (128 > > seconds is the default maximum length). Remaining numbers count > > abnormal conditions as explained below. > > --- end --- > > > > How can I make it stop earlier? At 64 s for example? > > > > Any ideas? > > > > TIA, > > Miguel > > _______________________________________________ > > 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. > > > > -- > > Chris Albertson > Redondo Beach, California > -- Chris Albertson Redondo Beach, California

RK

Rob Kimberley

Wed, May 15, 2013 11:20 AM

Check if you have a Max Poll setting in your config file.

max poll 5 = 32 seconds
max poll 6 = 64 seconds
max poll 7 = 128 seconds

Rob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Miguel Barbosa Gonçalves
Sent: 15 May 2013 01:31
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] NTP, PPS and < 10 us offsets

Hi!

I am trying to figure out why NTP takes so long to react to oscillator
changes... I want it to track the PPS from a Trimble Acutime as closely as
possible.

When checking ntptime on startup I see that the NTP daemon is using PLL and
starts the adjustment interval at 8 s. It then increases to 16, 32, 64, 128
and stops at 256.

I read in the documentation that this limit should be 128 but is now 256.

--- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm --- intervals
57 says that there were 57 calibration intervals. When PPS pulses are
arriving, this number should increase. Each frequency adjustment requires a
good calibration interval. The length of the current calibration interval
can be found as interval 128 s (128 seconds is the default maximum length).
Remaining numbers count abnormal conditions as explained below.
--- end ---

How can I make it stop earlier? At 64 s for example?

Any ideas?

TIA,
Miguel

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.

Check if you have a Max Poll setting in your config file. max poll 5 = 32 seconds max poll 6 = 64 seconds max poll 7 = 128 seconds Rob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Miguel Barbosa Gonçalves Sent: 15 May 2013 01:31 To: Discussion of precise time and frequency measurement Subject: [time-nuts] NTP, PPS and < 10 us offsets Hi! I am trying to figure out why NTP takes so long to react to oscillator changes... I want it to track the PPS from a Trimble Acutime as closely as possible. When checking ntptime on startup I see that the NTP daemon is using PLL and starts the adjustment interval at 8 s. It then increases to 16, 32, 64, 128 and stops at 256. I read in the documentation that this limit should be 128 but is now 256. --- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm --- intervals 57 says that there were 57 calibration intervals. When PPS pulses are arriving, this number should increase. Each frequency adjustment requires a good calibration interval. The length of the current calibration interval can be found as interval 128 s (128 seconds is the default maximum length). Remaining numbers count abnormal conditions as explained below. --- end --- How can I make it stop earlier? At 64 s for example? Any ideas? TIA, Miguel _______________________________________________ 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@lists.febo.com

NTP, PPS and < 10 us offsets