Re: [ntp:questions] Time of by 4 min

[Richard B. Gilbert]

On 3/14/2014 12:10 AM, David Taylor wrote:

On 13/03/2014 17:48, greg.wayne.sm...@gmail.com wrote:

That's a pretty slick program just from looking at the page. I will
play around with in and see. I tend to not install any 3rd party apps
on my DC's though.

I did mine the old fashion way by just setting the registry settings.
Basically this for Windows servers: http://www.pool.ntp.org/en/use.html

I have never had any issues till about 3 weeks ago.
My server is not slowing losing time... It's a solid 4 min off for the
past 3 weeks.


Some versions of the Windows Time Service are broken - e.g. they get a
time update once a week.  I strongly recommend using NTP from the
Meinberg install set and updating to the latest development version,
especially on your DCs.

[Caveats: I haven't used the Windows Time Service for many years, and I
believe it is a little better now, and I don't run a domain.]



If you really need accurate and reliable time, forget about getting it 
from the internet!  It will do for catching the bus and/or the train!


I get the time from earth atomic clocks in earth satellite clocks with 
atomic clocks on board.


I've been retired for about nine years and no longer need to make all 
the clocks agree.  It's just habit! :-)


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Re: [ntp:questions] Roof antenna, which one, would you bother?

[Richard B. Gilbert]

On 1/3/2014 5:54 AM, Ralph Aichinger wrote:

I am currently in the process of remodeling my house
and a dedicated outdoor/roof mounted GPS antenna
would be possible to mount without excessive cost.

I probably would not see a huge difference for
timing purposes, but what would your choice of
an outdoor GPS antenna/receiver be? I am planning
to put the NTP server (small Raspberry Pi, nothing
fancy) into a rack maybe 10 metres of cable length away
from the roof. Or would you move the NTP host itself
to the attic and run Ethernet up?

I suppose something like the Garmin GPS 17x (mast mount
GPS with serial output and PPS, intended for the marine
market) would work fine, also be robust enough and
cheap on the used market.

Would mounting just an antenna (active or passive) also
make sense, or would cable loss be too high?

What would *your* roof top setup be? Cost is of course
an important consideration, on the other hand, 100
or 200 Euros for the GPS, antenna and mounting hardware
is probably OK. I would prefer to do cabling jobs now,
while I am in the process of doing a lot of "dirty" things.

Or would you not bother at all, and just put some puck into
the window (which probably works too)?

TIA
/ralph



I have a GPS Antenna sitting on on top of a rain gutter.  The gutter
is a "RainGuard" (TM).  I haven't had to clean my rain gutters since I
installed the RainGuard. About ten years! YMMV!!!

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Re: [ntp:questions] NTP not syncing

[Richard B. Gilbert]

On 12/7/2013 7:35 PM, Magnus Danielson wrote:

On 12/07/2013 11:39 PM, Harlan Stenn wrote:

Magnus Danielson writes:

The drift-file-accelerated lock-in isn't robust. Current behavior of
response isn't very useful for most people experiencing it.

I'm not sure I'd agree with the word "most".  It's certainly worked very
well on hundreds of machines where I've run it, and the feedback I've
had from people when I've told them about iburst and drift files has
been positive except when they've had Linux kernels that calculate a
different clock frequency on a reboot.

Experiencing the problem that is. When it works, it's a lovely tool.
Sorry if the wording was unclear in that aspect.

There are at least 2 other issues here.

One goes to "robust", and yes, we can do better with that.  It's not yet
clear to me that in the wider perspective this effort will be worthwhile.

Well, you can either choose a rather simple back-out method or if you
think it is worthwhile a more elaborate method. Getting cyclic re-set of
time is a little to coarse a method. I think it is better to back-out
and one way or another recover phase and frequency.

The other goes to the amount of time it takes to adequately determine
the offset and drift.

With a good driftfile and iburst, ntpd will sync to a handful of PPM in
about 11 seconds' time.

We've been working on a project to produce sufficiently accurate offset
and drift measurements at startup time, and the main problem here is
that it can take minutes to figure this out well, and there is a
significant need to get the time in the right ballpark at startup in
less than a minute.  These goals are mutually incompatible.  The intent
is to find a way to "get there" as well as possible, as quickly as
possible.

Getting the time in the right ball-park is by itself not all that hard.
However, frequency takes time to learn and getting phase errors down
quickly becomes an issue. NTP has as far as I have seen reduced loop
bandwidth and at the same time reduced the capture range, and whenever
you reduce the capture range you need to have heuristics to make sure
you back-out if things get upset. Recovery of old state is good, but one
needs to make sure that you don't loose that robustness.

As for method of locking in quickly, that can be debated on in length.

Cheers,
Magnus



It has been debated!  It will probably be debated for the next thirty
or forty years.  There is something about the topic that seems to
to encourage debate! ;-)

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Re: [ntp:questions] Is there something with greater detail on "interface" besides the manpage?

[Richard B. Gilbert]

On 11/21/2013 8:27 AM, John Hasler wrote:

mike cook writes:

As a comment to lead OL. We are now in a situation where we can only
trust our enemies. CAcert.org is an Australian based org IIRC. They
are in the same "Trust" league as the US, UK, CAN, all of whom have
proved to be woefully lacking in probity.


Are you afraid that the NSA is going to find out how you are setting
your clock?



NSA already knows how you are setting your clock!  There is no escape! ;-)

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Re: [ntp:questions] Trying to use Dimension 4 time keeper

[Richard B. Gilbert]

On 9/10/2013 9:47 PM, W. eWatson wrote:

...




I tried Meinberg for quite some time, but it flops fairly often. As I


flops? What are the symptoms? Also, if time is important why not invest
in a GPS (35 dolalrs or so) with PPS.


It moves many seconds in a short time, say a day or two. How is GPS
going to help? Does it provide access via a USB port.


It-- which noun does that "it" point to?
Sure, you can have gps provide access via a usb port. The Sure GPS even
has a usb port on board that you can directly connect to. It is not
great timekeeping but you can probably get it to within .1 sec or so.
The main problem is that you cannot use the PPS via a usb connection, so
you have to rely on the timing from the nmea sentences. Run the usb port
as fast as possible (high baud rate), and after some observation with
the machine connected to the internet as well, determine what the usb
data time offset is and subtract it out using the time2 option to the
driver.

It = GPS. What is PPS?
...


Pulse per second ???

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Re: [ntp:questions] DNS resolution on ntpd

[Richard B. Gilbert]

On 8/11/2013 9:03 AM, Marco Marongiu wrote:

I looked up "dns", "resol", and "ip" to no avail.
  Am I missing something?


Maybe dynamic or pool?





Thanks!
-- M




Some people seem to love to use short hand code!!

DNS == Domain Name Server. "
It's the device and software that translates  a computer's name to its 
IP Address.


If you're lucky somebody will translate "computer speak"
to English, French,Spanish (Espanol), Deutch (German), Japanese, Chinese 
. . . .


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Re: [ntp:questions] client configuration: it's sufficient 3 servers ?

[Richard B. Gilbert]

On 5/24/2013 5:56 AM, David Lord wrote:

Riccardo Castellani wrote:

If I have 3 internal NTP servers, what do you think if my clients have
all these 3 servers in their configuration ?
According to '5.3.2. Why should I have more than one clock?' in
'http://www.ntp.org/ntpfaq/NTP-s-algo-real.htm#Q-NTP-ALGO


I read 2 servers, it's worst case, but also 3...


My four pool servers each have 5 x internet sources
(= 20 different internet sources) and 2 x local peers,
there are also local sources with MSF and GPS.

There is an explanation of the selection algorithm in
the ntpd documentation as to why having only 2 and 3
sources can give problems. That sets 4 as minimum and
5 for safety.

I've had internet outages where half the sources have
become unreachable.

David



The internet is far from the best source of time!  A lot of time is
spent trying to make sense of all the noise!

A gadget whose name I can't remember will lock onto three earth 
satellites and give you time to plus/minus 50 nano seconds.  Very few

people need to slice time that fine!


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Re: [ntp:questions] ntp & system without a rtc

[Richard B. Gilbert]

On 5/10/2013 8:30 PM, unruh wrote:

On 2013-05-10, Rick Jones  wrote:

Richard B. Gilbert  wrote:

I think you may be out of luck on this one.  If you can run NTPD 24x7
you can have the correct time 24x7.  If you can't do this, NTPD is a
poor choice.  The problem is that NTPD needs something like ten hours to
select a time source and match the time!


NTPD is no speed daemon, and perhaps it is a subjective thing, or a
mis-interpreation on my part, but I notice NTPD declaring sync rather
sooner than 10 hours.  Rather sooner than one hour even (looking at
ntpq -p output).  Now, it may indeed take it a long time to get the
offset (term?) down to some acceptable level, but that depends on
one's definition of acceptable and the initial distance no?


Yes. The 10 hours is for achieving the ultimate accuracy of a few
microseconds offset. It has a halving time of a bit under an hour (lets
say 45 min) . Ie,
after 45 min, the size of the offsets is about 1/2 of what it
was before. Because of stepping it has an error of about 100ms to start
out.
If you are happy with few millisecond precision, it will only take an hour
or two.

So if you start it out with the -g it will figure out is is way out
after a few seconds, and step. But the rate in general will still be
out, so it will rapidly drift away and ntpd will slowly bring the drift
into order.

Thus to get from hours out to hundreds of milliseconds out should occur
very quickly.


rick jones


NTPD is NOT designed for fast convergence.  From start up to get the 
minutes correct, NTPD will need about thirty minutes!  To get the best 
time you are going to get, you will need to wait for about ten hours!


If fast convergence is your goal, you can use a a program called
CHRONY to achieve it.

If your goal is to know the time +/- 50 nanoseconds You are expected to 
operate your clock twenty-four hours a day.


With a GPS Timing Receiver you can keep time +/- 50 nano-seconds. 
Relatively few people NEED time with that sort of accuracy.  Many

who DO need that accuracy use NTP and a Global Positioning Satellite
to get the accuracy required.  A few of these people read this
newsgroup.


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Re: [ntp:questions] ntp & system without a rtc

[Richard B. Gilbert]

On 5/10/2013 10:36 AM, folkert wrote:

Hi,

I have a raspberry pi system. This is a computer without a real time
clock. So everytime I power it on, it uses starts where it left off
which might be days earlier. It is connected only very occasionally to
the internet so syncing to that won't work. It does have, however, a gps
connected. But as it is switched mostly for less than an hour, ntpd
won't have the time to adjust the time to what the gps returns to it.
So I was wondering: is there a utility/a trick out there that picks the
current time from a gps and then "jumps" the time to what it should be?
It does not need to be very accurate - a couple of seconds off is ok
(just not hours or days).

Any ideas?


Regards,

Folkert van Heusden



I think you may be out of luck on this one.  If you can run NTPD 24x7
you can have the correct time 24x7.  If you can't do this, NTPD is a 
poor choice.  The problem is that NTPD needs something like ten hours to 
select a time source and match the time!


There is another "product" called "chrony" that has MUCH faster 
convergence.  I't never used chrony and can't tell you much about it.


I run 24x7 and seldom have to shut down and restart.

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Re: [ntp:questions] high jitter on serial gps causes big time offsets

[Richard B. Gilbert]

On 4/13/2013 5:09 PM, David Woolley wrote:

website.read...@gmail.com wrote:


I can obtain some precision crystals (+/- 2ppm) for about $8 to $10,

+ so why aren't they being added to the mid-level and up motherboards?

$8-10 for the crystal would imply a total motherboard price of $2,000+.

I think the big market for high end motherboards is gamers, and they are
not interested in accurate real time.  The rest of the PC market
probably finds the issue too technical.


PC's clocks are often chosen for price rather than micro, or nano second 
timing accuracy.


Personally, I have little need for anything much more than hours and 
minutes!


If you need, or just want micro or nano ticks, I believe you can get
them

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Re: [ntp:questions] Extracting ntpq like information programmatically

[Richard B. Gilbert]

On 3/29/2013 3:27 PM, Claudio Carbone wrote:

On 29/03/13 19:26, Brian Utterback wrote:

As unruh said, if there was a way to improve the accuracy of the
measurement over the network like that, NTP would already be doing it.


If so why doesn't the offset oscillate?
If NTP were a real compensation system, it should oscillate around the
setpoint.
Instead I noticed a nearly static offset, at least during the 15 minutes
observation time.

Claudio


NTP can require about ten hours to reach steady state; that means the 
best time that you are going to get.  Once NTPD reaches steady state
all you have to worry about are things like power failure or air 
conditioning failure!



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Re: [ntp:questions] NIST vs. pool.ntp.org ?

[Richard B. Gilbert]

On 3/28/2013 8:22 AM, Magnus Danielson wrote:

On 03/27/2013 10:45 PM, David Woolley wrote:

Robert Scott wrote:

I am confused about the proper usage of pool.ntp.org and NIST.
pool.ntp.org seems to be a collection of private sector time servers
offered for all to use, but with registration expected for regular


The pool system has no provision for enforcing registration. It wouldn't
make sense to hand out a random server address if most of them then
refused to serve you because you hadn't registered.


users. And NIST has a government run set of time servers. Neither
group (NIST or pool.ntp.org) seems to include or referece the other.


I would hope all the pool servers ultimately reference their national
equivalent of NIST and therefore what becomes, after the fact, UTC.

I think you will find that Navstar (GPS) and WWV times are traceable to
NIST.


Yes and no.

GPS is traceable to USNO. USNO and NIST have traceability between each
other within the BIPM framework.


MSF times are traceable to NPL.


NPL is traceable to both USNO and NIST within the BIPM framework.


Are they in competition? Who normally uses the NIST servers and who
uses pool.ntp.org?


The open NIST servers are heavily overloaded, so probably don't serve
the highest quality time, but they are likely to be around for a long
time.


I would setup a local server under your control. It will help both from
debugging and noise perspective.

Cheers,
Magnus


If you really want the best time, consider a GPS Timing Receiver.  The 
GPS Timing Receiver should give you a "tick" that's +- 50 nanoseconds. 
If you need better, you will need your own "atomic clock"!  It also 
gives you the "value" of that tick; e.g. 4:03:32. . . . .


Many of us here do not actually need +/- 50 nanoseconds.  What I DID 
want was to have all the clocks in all the "clocks" in the house in 
agreement! It's not perfect but it's close enough. . . .


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Re: [ntp:questions] NIST vs. pool.ntp.org ?

[Richard B. Gilbert]

On 3/27/2013 3:20 PM, Robert Scott wrote:

I am confused about the proper usage of pool.ntp.org and NIST.
pool.ntp.org seems to be a collection of private sector time servers
offered for all to use, but with registration expected for regular
users.  And NIST has a government run set of time servers.  Neither
group (NIST or pool.ntp.org) seems to include or referece the other.
Are they in competition?  Who normally uses the NIST servers and who
uses pool.ntp.org?

I posted here several months ago about my specific application.  I
want to use SNTP, not to synchronize a system clock but to make a
frequency measurement on the audio sampling rate in a smartphone.  My
use of time servers will be very occasional - typically a user of my
app would only use the time servers once when the app is first
installed to do a calibration of the audio sampling rate in that
phone.  And my app will have very limited circulation.  So I won't be
hitting the servers very often at all.

Today I found the last bug that prevented me from getting response
from the time servers in my socket code.  I had neglected to set the
port number (123) using htons(123) to put the port number in network
byte order.  When I fixed that I finally started getting responses.

I have gotten responses from pool.ntp.org as well as several of the
NIST time servers listed on their website.  However the round-robin
address of time.nist.gov does not seem to return anything.  The recv()
function just times out.  And I sure don't want to hard-code any of
the other NIST server URLs in my app.  I was going to go with
pool.ntp.org until I saw the NIST servers that did not seem to be part
of the pool.

So I guess my main question is which servers should I use for my very
limited application?

Robert Scott
Hopkins, MN



I think you need to start by defining the quality of time you need.  Is
4:13 PM Eastern Timegood enough?  Some people just want to "Get me to 
the church on time!"  OR the bus, or the train or plane.  A radio 
astronomer is almost certainly going to insist on time to the nearest 
nano second.


Most of the range above is probably going to be "overkill" for most people.

Please try to define your requirements a little more closely! 
Nano-seconds, "get me to the church/train/plane . . . . on time!"  or 
something else.


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Re: [ntp:questions] multiple instances of NTP on different interfaces

[Richard B. Gilbert]

On 3/4/2013 11:13 PM, Abu Abdullah wrote:

On Mon, Mar 4, 2013 at 11:12 PM, E-Mail Sent to this address will be added
to the BlackLists  wrote:


Abu Abdullah wrote:

I'm trying to run two instances of ntp




What problem are you trying to solve?

The two NTP processes cannot serve identical times; there will be
a difference between the two instances!

They are going to fight each other to discipline the system clock?


Quite probably!




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Re: [ntp:questions] Two GPIO PPSes on Raspberry Pi

[Richard B. Gilbert]

On 2/28/2013 6:03 PM, Chris Adams wrote:

Once upon a time, Ralph Aichinger   said:

Has anybody *two* GPIO PPS devices on different GPIO
pins on their Raspberry Pi? Would a setup like this
enable the ntpd to check the devices against eachother
(or probably more likely give an idea of interrupt
handling capabilities)?


Remember: a man with two clocks never knows what time it is.

If they are the same, everything's great; if they are different, what do
you do?



This looks so simple!!!  Is there a "catch" somewhere?

Try adding a third clock.  If NO TWO CLOCKS AGREE
you have a serious problem.

If you are relying on time from the Internet, that
may be your one of your problems!!!

I use a Global Positioning System (GPS) Timing Receiver
and get time good enough for most purposes.

It's specified +/- 50 nanoseconds.

If you need better, you can get it but you have some
studying to do and you had better have a "deep pocket"!
If your "deep Pocket" is not full of $1000 bills. . . .

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Re: [ntp:questions] PPS only configuration

[Richard B. Gilbert]

On 2/21/2013 1:08 PM, Mike S wrote:

On 2/21/2013 8:52 AM, Brian Utterback wrote:

Having said that, I note that Ed Mischanko's mailer is not sending
text/plain flowed. So unruh has a point in that case.

On 2/21/2013 8:38 AM, Brian Utterback wrote:

Hate to get into a religious war here, but there is a hard, factual
standard here. RFC2646 which defines the MIME type text/plain format
parameter.


RFC2646 isn't a standard. It's an RFC, just like RFC1149. The standard
is STD11 (from RFC822). It places no restriction on the length of lines
in the body. The planned replacement (draft standard) is RFC5322, which
is quite clear that an MUA which can't handle long lines is
"non-conformant."

"2.1.1.  Line Length Limits

There are two limits that this specification places on the number of
characters in a line.  Each line of characters MUST be no more than
998 characters, and SHOULD be no more than 78 characters, excluding
the CRLF.

The 998 character limit is due to limitations in many implementations
that send, receive, or store IMF messages which simply cannot handle
more than 998 characters on a line.  Receiving implementations would
do well to handle an arbitrarily large number of characters in a line
for robustness sake.  However, there are so many implementations that
(in compliance with the transport requirements of [RFC5321]) do not
accept messages containing more than 1000 characters including the CR
and LF per line, it is important for implementations not to create
such messages.

The more conservative 78 character recommendation is to accommodate
the many implementations of user interfaces that display these
messages which may truncate, or disastrously wrap, the display of
more than 78 characters per line, in spite of the fact that such
implementations are non-conformant to the intent of this
specification (and that of [RFC5321] if they actually cause
information to be lost)."


I think that many hardware terminals e.g. VT100 or VT320 do not handle 
long lines well.


I can't see any reason why anyone would need to send more than 132 
characters in one line of text!


You may have noted that books, magazines and newspapers limit their line 
lengths.


There are sound reasons for that!  So PLEASE take your nine hundred 
character line and break it up!


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Re: [ntp:questions] PPS only configuration

[Richard B. Gilbert]

On 2/21/2013 8:38 AM, Brian Utterback wrote:

Hate to get into a religious war here, but there is a hard, factual
standard here. RFC2646 which defines the MIME type text/plain format
parameter. If you are reading a message with content type text/plain and
format set to "flowed", and a non-quoted line of words appears that is
too long (for various values of "too long", mostly between 60 and 80
characters or wider than your screen) then the problem is with the
reader you are using. Period. I note that the message above with the
1500 character line of text is content type text/plain with format flowed.

Brian Utterback.


I'm not sure that I'm getting your point here. 90% PLUS of text posted 
here can be rendered as readable text with little or nothing required of

the reader other than the ability to read English text.

I'm using a Personal Computer to emulate a DEC "VT-100" terminal.  If 
necessary I could plug in a DEC/Compaq/HP VT-320 Terminal.  I find it 
easier to use an emulation by my PC.  It works and has worked for the

last twenty years plus or minus . . . .



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Re: [ntp:questions] PPS only configuration

[Richard B. Gilbert]

On 2/20/2013 5:00 PM, E-Mail Sent to this address will be added to the 
BlackLists wrote:

On 2/20/2013 12:17 PM, Richard B. Gilbert wrote:

The Thunderbird Mail Client does NOT automagically insert
 line breaks when the sender has failed to do so.
Fortunately, almost everyone limits their line length
 to what will fit on most video terminals.

Thank you and please continue to limit your line length!


Thunderbird, there is [CRTL]R Edit ReWrap

Also in Thunderbird you can change you config as needed: e.g.
  Tools -> Options -> Advanced: Config Editor,
   mailnews.display.disable_format_flowed_support false
   mailnews.send_plaintext_flowed true
   mailnews.wraplength 65

   mail.compose.wrap_to_window_width true
   mail.wrap_long_lines true

Below is a 1000 char line that displays as about 150 characters per line
on my full screen display, I guess we'll see how it comes out on the
other end.

123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789 123456789 123456789 123456789 123456789 123456789
123456789 123456789




Thunderbird Mail/News Client renders the above as seven, nine character 
columns.  The columns are separated by single spaces.  No problem 
reading it!


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Re: [ntp:questions] PPS only configuration

[Richard B. Gilbert]

On 2/19/2013 8:10 PM, E-Mail Sent to this address will be added to the 
BlackLists wrote:

Rob wrote:

Actually, their posts are much easier to read for almost
  everyone, as amost every newsreader (except yours,
  apparently) will wrap their text into the space available.

The idea of sending every paragraph as a single line and
  then leave the formatting to the receiver was actually
  a very good idea.  It works better than having the sender
  wrap the lines, because the sender does not know what font
  the receiver uses, or the width of his window.
Sender-side wrapping was devised in the days that everyone
  had an 80 character wide screen, and already caused
  problems back then for those that had different screens.


I think you have a lot of general netiquette guidelines
   to submit suggested changes to then (almost all of them).

  As well as Several STDs / RFCs / BCPs / FYIs,
   (RFC5322, RFC1855 ?)

  Then also get everyone to implement RFC3676
compliant senders and readers?

   Then get people to use them.


  Everyone might catch up about the time your great grandchildren
   start complaining about the same topic.


  Then again usenet was going to become unusable after
   September 1993, unless within a month new users were
conforming to _existing_ usenet netiquette (like line length),
 if not, then usenet would become unusable, and collapse ?



The Thunderbird Mail Client does NOT automagically insert line breaks
when the sender has failed to do so.  Fortunately, almost everyone
limits their line length to what will fit on most video terminals.

Thank you and please continue to limit your line length!

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Re: [ntp:questions] PPS only configuration

[Richard B. Gilbert]

On 2/18/2013 10:27 AM, Steve Kostecke wrote:

On 2013-01-19, unruh  wrote:


Mischanko posts a long post with a single line, saying he wants help
in finding a news poster which will break lines for him. He has one.
Himself. It is entirely possible to put in line breaks manually, which
I, sarcastically I admit, pointed out to him. Not putting in line
breaks is NOT primarily a news posting problem. It is a user problem.


According to the headers in your article(s) you are using the slrn
newsreader. So all you have to do to make long lines of text readable is
touch the 'w' key while you're reading the offending article.



And what do you do if you are not using the "slrn" newsreaders.

I have an "Enter" key on my keyboard and I use it!  It doesn't seem to
me to be "rocket science" to use an "Enter" key, or a "Return" key 
somewhere between 1 and 120 characters.  Most PCs, terminals or printers 
should be able to render it.


Most of the "horrible examples" seem to be using MicroSoft malware.
In one case I noticed fairly recently, the offender seemed to have
cut and pasted from MicroSoft Word or a similar product.  Presumably,
some MicroSoft product will render it so you can read it.  The problem 
there is that a lot of people are not using Microsoft products for all 
tasks.  MicroSoft is EXPENSIVE.  There are alternatives that some of us 
use to avoid bankruptcy!


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Re: [ntp:questions] X2 assert and clear events (PPS) on LInux with sure GPS Board

[Richard B. Gilbert]

On 1/14/2013 3:18 PM, E-Mail Sent to this address will be added to the 
BlackLists wrote:

Edward T. Mischanko wrote:

Does Richard B. Gilbert have nothing better to say,
  than to post the same reply 5 times,


I think it is very likely that his news or mail, client or service
  is having issues.



I apologize on behalf of my computer, software, etc, and my fumble 
fingers if they were involved.  Also my fumbling mind, if THAT was

involved.

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Re: [ntp:questions] X2 assert and clear events (PPS) on LInux with sure GPS Board

[Richard B. Gilbert]

On 1/9/2013 7:09 PM, unruh wrote:

On 2013-01-09, thelastroman...@live.fr  wrote:

Hi,

Thanks, it seems to work.

So, i just need nanoseconds precision with this 1pps on my localhost,
don't need NTP or other.


You will NOT get nanosecond precision. If that is your goal, give up
now. No computer can reach that. a)the time sources are not good enough
without corrections after the fact, and b) your computer cannot process
the pps signal fast enough to give you that precision.



I've have compiled succefully compiled my program with timepps.h,
and i want to create a nanoseconds chronometer between each 1PPS.
What function should i use from timepps.h code ?


You don't.



Another solution : i've modeed ppstest, and i settimeofday to "0" each PPS,
but the accuracy of settimeofday() seems to be bad, and i want just change
> the seconds to "0" on my local PC without change HH.MM and date. 
juste change

the seconds to "0" for each PPS/seconds

That takes too long. And if your frequency is out by 1PPM ( and that is
a very good computer clock if its drift is only 1PPM)  your clock
will be out by 1000 ns by the time the next pulse occurs.

Ie, you have set yourself and impossible task.



Sorry for my bad english


Your English is alright!  Have you noticed the linguistic
sins of some of the native speakers? ;-)

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Re: [ntp:questions] X2 assert and clear events (PPS) on LInux with sure GPS Board

[Richard B. Gilbert]

On 1/9/2013 7:09 PM, unruh wrote:

On 2013-01-09, thelastroman...@live.fr  wrote:

Hi,

Thanks, it seems to work.

So, i just need nanoseconds precision with this 1pps on my localhost,
don't need NTP or other.


You will NOT get nanosecond precision. If that is your goal, give up
now. No computer can reach that. a)the time sources are not good enough
without corrections after the fact, and b) your computer cannot process
the pps signal fast enough to give you that precision.



I've have compiled succefully compiled my program with timepps.h,
and i want to create a nanoseconds chronometer between each 1PPS.
What function should i use from timepps.h code ?


You don't.



Another solution : i've modeed ppstest, and i settimeofday to "0" each PPS,
but the accuracy of settimeofday() seems to be bad, and i want just change
> the seconds to "0" on my local PC without change HH.MM and date. 
juste change

the seconds to "0" for each PPS/seconds

That takes too long. And if your frequency is out by 1PPM ( and that is
a very good computer clock if its drift is only 1PPM)  your clock
will be out by 1000 ns by the time the next pulse occurs.

Ie, you have set yourself and impossible task.



Sorry for my bad english


Your English is alright!  Have you noticed the linguistic
sins of some of the native speakers? ;-)

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Re: [ntp:questions] X2 assert and clear events (PPS) on LInux with sure GPS Board

[Richard B. Gilbert]

On 1/9/2013 7:09 PM, unruh wrote:

On 2013-01-09, thelastroman...@live.fr  wrote:

Hi,

Thanks, it seems to work.

So, i just need nanoseconds precision with this 1pps on my localhost,
don't need NTP or other.


You will NOT get nanosecond precision. If that is your goal, give up
now. No computer can reach that. a)the time sources are not good enough
without corrections after the fact, and b) your computer cannot process
the pps signal fast enough to give you that precision.



I've have compiled succefully compiled my program with timepps.h,
and i want to create a nanoseconds chronometer between each 1PPS.
What function should i use from timepps.h code ?


You don't.



Another solution : i've modeed ppstest, and i settimeofday to "0" each PPS,
but the accuracy of settimeofday() seems to be bad, and i want just change
> the seconds to "0" on my local PC without change HH.MM and date. 
juste change

the seconds to "0" for each PPS/seconds

That takes too long. And if your frequency is out by 1PPM ( and that is
a very good computer clock if its drift is only 1PPM)  your clock
will be out by 1000 ns by the time the next pulse occurs.

Ie, you have set yourself and impossible task.



Sorry for my bad english


Your English is alright!  Have you noticed the linguistic
sins of some of the native speakers? ;-)

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Re: [ntp:questions] X2 assert and clear events (PPS) on LInux with sure GPS Board

[Richard B. Gilbert]

On 1/9/2013 7:09 PM, unruh wrote:

On 2013-01-09, thelastroman...@live.fr  wrote:

Hi,

Thanks, it seems to work.

So, i just need nanoseconds precision with this 1pps on my localhost,
don't need NTP or other.


You will NOT get nanosecond precision. If that is your goal, give up
now. No computer can reach that. a)the time sources are not good enough
without corrections after the fact, and b) your computer cannot process
the pps signal fast enough to give you that precision.



I've have compiled succefully compiled my program with timepps.h,
and i want to create a nanoseconds chronometer between each 1PPS.
What function should i use from timepps.h code ?


You don't.



Another solution : i've modeed ppstest, and i settimeofday to "0" each PPS,
but the accuracy of settimeofday() seems to be bad, and i want just change
>the seconds to "0" on my local PC without change HH.MM and date. juste 
change the seconds to "0" for each PPS/seconds


That takes too long. And if your frequency is out by 1PPM ( and that is
a very good computer clock if its drift is only 1PPM)  your clock
will be out by 1000 ns by the time the next pulse occurs.

Ie, you have set yourself and impossible task.



Sorry for my bad english


Your English is alright!  Have you noticed the linguistic
sins of some of the native speakers? ;-)

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Re: [ntp:questions] X2 assert and clear events (PPS) on LInux with sure GPS Board

[Richard B. Gilbert]

On 1/9/2013 7:09 PM, unruh wrote:

On 2013-01-09, thelastroman...@live.fr  wrote:

Hi,

Thanks, it seems to work.

So, i just need nanoseconds precision with this 1pps on my localhost,
don't need NTP or other.


You will NOT get nanosecond precision. If that is your goal, give up
now. No computer can reach that. a)the time sources are not good enough
without corrections after the fact, and b) your computer cannot process
the pps signal fast enough to give you that precision.



I've have compiled succefully compiled my program with timepps.h,
and i want to create a nanoseconds chronometer between each 1PPS.
What function should i use from timepps.h code ?


You don't.



Another solution : i've modeed ppstest, and i settimeofday to "0" each PPS,
but the accuracy of settimeofday() seems to be bad, and i want just change the seconds to 
"0" on my local PC without change HH.MM and date. juste change the seconds to 
"0" for each PPS/seconds


That takes too long. And if your frequency is out by 1PPM ( and that is
a very good computer clock if its drift is only 1PPM)  your clock
will be out by 1000 ns by the time the next pulse occurs.

Ie, you have set yourself and impossible task.





Sorry for my bad english


Your English is alright!  Have you noticed the linguistic
sins of some of the native speakers? ;-)

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Re: [ntp:questions] FLL instability

[Richard B. Gilbert]

On 1/6/2013 3:45 AM, Mischanko, Edward T wrote:



-Original Message-
From: questions-
bounces+edward.mischanko=arcelormittal@lists.ntp.org
[mailto:questions-
bounces+edward.mischanko=arcelormittal@lists.ntp.org] On
Behalf Of David Taylor
Sent: Sunday, January 06, 2013 2:18 AM
To: questions@lists.ntp.org
Subject: Re: [ntp:questions] FLL instability

On 06/01/2013 06:29, Mischanko, Edward T wrote:

I have "tinker allan 7" in my ntp.conf, as recommended, but I

notice that the frequency is adjusting wildly starting with
polling at 128 seconds.  Is something wrong with the way FLL is
implemented?
[]

Where is this recommended?  URL, please.  I've never had the
need to use
this tinker myself, so I wonder whether it's some situation
which
doesn't apply to me.
--
Cheers,
David
Web: http://www.satsignal.eu

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[Mischanko, Edward T]
This was recommended to me on this list several months ago.  I am running my 
windows client on a corporate LAN and it was suggested that the PLL would not 
correct fast enough at polling intervals over 128 seconds.  The problem I am 
seeing is that when FLL is implemented the frequency swings excessively and the 
offset does not train toward zero.  This would not be needed for setups using 
GPS/PPS reference clocks.

Regards,
Ed



Please use your "Return" or "Enter" key.  MicroSoft will let you write 
lines in excess of 500 characters.  It's rather tough for many of us to 
read it.


You may have other problems but you should expect NTPD to need as long 
as ten hours to settle.  If you are trying to run "9 AM to 5 PM you have 
made some poor choices.  NTPD can take up to TEN HOURS to get the best 
time you can get.  Once it's settled, it should not have any problem 
maintaining synchronization.


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Re: [ntp:questions] NTP.ORG MEINBERG KEEP TIME ACCURATE to 10MS

[Richard B. Gilbert]

On 11/14/2012 8:33 PM, gbusenb...@yahoo.com wrote:

On Wednesday, November 14, 2012 7:32:52 PM UTC-5, Richard B. Gilbert wrote:

On 11/14/2012 12:02 AM, E-Mail Sent to this address will be added to the BlackLists wrote: > gbusenb...@yahoo.com wrote: >> I am now left with two lines in ntp.conf >> driftfile "C:\Program 
Files\NTP\etc\ntp.drift" >> server 10.1.126.204 iburst minpoll 5 > > There have been plenty of improvemnets since 4.2.6p5 circa 2011Dec24 > 
<http://www.davehart.net/ntp/win/x86/ntp-4.2.7p310-win-x86-debug-bin.zip> > <http://www.davehart.net/ntp/win/x86/ntp-4.2.7p310-win-x86-debug-sym.zip> > > # ALL (Clients and/or Servers) > # 
Start the Service with C:\Program Files\NTP\bin\ntpd.exe -U 3 -M -g -c "C:\Program Files\NTP\etc\ntp.conf" > # the -g will prevent a panic stop if the time needs to be steped when started > > # 
ntp.conf > driftfile "C:\Program Files\NTP\etc\ntp.drift" > statsdir "C:\Program Files\NTP\etc\" > enable monitor > enable stats > statistics loopstats peerstats > keys 
"C:\Program Files\NTP\etc\ntp.keys" # e.g. contains: 123 M YOUR_MD5_KEY > trustedkey 123 > tos cohort 1 orphan 1

1 > restrict default limited kod nomodify notrap > restrict 127.0.0.1 > restrict source nomodify > broadcastclient > 
manycastserver 224.0.1.1 > multicastclient 224.0.1.1 key 123 preempt > manycastclient 224.0.1.1 key 123 preempt > pool 
pool.ntp.org preempt # Won't hurt anything if the internet can't be reached > server 10.1.126.204 iburst key 123 > > # If you 
address the server by name append preempt > # Let NTP worry about the minpoll and maxpoll for LAN devices > > # They should all 
try to sync to 10.1.126.204 > # If they can't reach 10.1.126.204 they should all try to stick together > > # NTP expects to be run 
continuously; After a Boot/Reboot/Restart/... > # give the systems 30 minutes to stabilize polls and temperature > # before expecting 
too much from the ntpq stats > 30 minutes is more than a little optimistic! NTPD needs something like ten hours to stabilize with the 
best time you are going to get. Thirty minutes after startup is about when NTPD gets days, hours, and minutes
right. The next nine and a half hours will be devoted to improve the accuracy. 
This should suggest to you that NTDP should be run 24 hours a day, seven days a 
week. . . . . It's not always possible, but TRY!


I agree.  After everything is working, it will stay up running 24/7.  The hard 
thing is that each time I make a change, I have to give it a day to stabilize 
like you mentioned.



Why must you make changes?  Get it running properly and leave it alone. 
 Use an uninterruptable power supply if possible.


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Re: [ntp:questions] NTP.ORG MEINBERG KEEP TIME ACCURATE to 10MS

[Richard B. Gilbert]

On 11/14/2012 12:02 AM, E-Mail Sent to this address will be added to the 
BlackLists wrote:

gbusenb...@yahoo.com wrote:

I am now left with two lines in ntp.conf
driftfile "C:\Program Files\NTP\etc\ntp.drift"
server 10.1.126.204 iburst minpoll 5


There have been plenty of improvemnets since 4.2.6p5 circa 2011Dec24



# ALL (Clients and/or Servers)
#  Start the Service with C:\Program Files\NTP\bin\ntpd.exe -U 3 -M -g -c 
"C:\Program Files\NTP\etc\ntp.conf"
#   the -g will prevent a panic stop if the time needs to be steped when started

# ntp.conf
driftfile "C:\Program Files\NTP\etc\ntp.drift"
statsdir "C:\Program Files\NTP\etc\"
enable monitor
enable stats
statistics loopstats peerstats
keys "C:\Program Files\NTP\etc\ntp.keys" # e.g. contains: 123 M YOUR_MD5_KEY
trustedkey 123
tos cohort 1 orphan 11
restrict default limited kod nomodify notrap
restrict 127.0.0.1
restrict source nomodify
broadcastclient
manycastserver  224.0.1.1
multicastclient 224.0.1.1 key 123 preempt
manycastclient  224.0.1.1 key 123 preempt
pool pool.ntp.org preempt# Won't hurt anything if the internet 
can't be reached
server 10.1.126.204 iburst key 123

# If you address the server by name append preempt
# Let NTP worry about the minpoll and maxpoll for LAN devices

# They should all try to sync to 10.1.126.204
#  If they can't reach 10.1.126.204 they should all try to stick together

# NTP expects to be run continuously; After a Boot/Reboot/Restart/...
#  give the systems 30 minutes to stabilize polls and temperature
#   before expecting too much from the ntpq stats

30 minutes is more than a little optimistic!  NTPD needs something like 
ten hours to stabilize with the best time you are going to get.  Thirty 
minutes after startup is about when NTPD gets days, hours, and minutes

right.  The next nine and a half hours will be devoted to improve the
accuracy.

This should suggest to you that NTDP should be run 24 hours a day, seven 
days a week. . . . .


It's not always possible, but TRY!


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Re: [ntp:questions] What is the NTP recovery time from 16s step in GPSserver?

[Richard B. Gilbert]

On 10/31/2012 5:04 PM, unruh wrote:

On 2012-10-31, Richard B. Gilbert  wrote:

On 10/31/2012 4:30 AM, David Woolley wrote:

Kennedy, Paul wrote:

I believe the answer to your question is 12.5 minutes.

This is the time it takes to receive the full set of 25 almanac frames,
which contains the GPSTime/UTC offset (amongst other things).

http://en.wikipedia.org/wiki/GPS_signals#Almanac


I think he knows the time taken for the GPS receiver, which is a lot
less than that.  His concern is about how long ntpd takes once the GPS
receiver is reporting the correct time.  As noted, ntpd is not specified
for this case, so makes no attempt to recover any faster than any other
broken local clock case.

The almanac you are referring to is a low resolution one to aid the
receiver in finding satellites after a cold start.  Once it has found a
satellite, it should have a high resolution almanac for that satellite
in about 30 seconds.  Modern receivers tend to decode multiple
satellites at once, which is how they get a fast start, so they may be
fully acquired in 30 seconds.  However, if there is no memory at all, it
may take them some tome to find their first satellite, and locating
subsequent ones may be slow until the full coarse almanac is received.



NTPD is a "slow starter"!  Ideally, you will only start it once and
let it run for a few months.

How slow is a "slow start"?.  It can take NTPD up to ten hours to
synchronize within + or - 50 nanoseconds with whatever you are using as


It will never get to within 50nsec. The interrupt processing is far more
variable than that. You might get to withing a few micro seconds.



a time source.  If you must boot your computer at 8:30 every morning,
NTPD is a poor choice!

There is another "product" which will give you a "reasonable facsimile"
of the correct time in a very short time.  I've never used it. I've
forgotten its name.  Sorry about that.  I'm sure that someone here
can recall the name I've forgotten!


Chrony.
It also gives better accuracy.


Accuracy long term or short term?



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Re: [ntp:questions] What is the NTP recovery time from 16s step in GPSserver?

[Richard B. Gilbert]

On 10/31/2012 4:30 AM, David Woolley wrote:

Kennedy, Paul wrote:

I believe the answer to your question is 12.5 minutes.

This is the time it takes to receive the full set of 25 almanac frames,
which contains the GPSTime/UTC offset (amongst other things).

http://en.wikipedia.org/wiki/GPS_signals#Almanac


I think he knows the time taken for the GPS receiver, which is a lot
less than that.  His concern is about how long ntpd takes once the GPS
receiver is reporting the correct time.  As noted, ntpd is not specified
for this case, so makes no attempt to recover any faster than any other
broken local clock case.

The almanac you are referring to is a low resolution one to aid the
receiver in finding satellites after a cold start.  Once it has found a
satellite, it should have a high resolution almanac for that satellite
in about 30 seconds.  Modern receivers tend to decode multiple
satellites at once, which is how they get a fast start, so they may be
fully acquired in 30 seconds.  However, if there is no memory at all, it
may take them some tome to find their first satellite, and locating
subsequent ones may be slow until the full coarse almanac is received.



NTPD is a "slow starter"!  Ideally, you will only start it once and
let it run for a few months.

How slow is a "slow start"?.  It can take NTPD up to ten hours to 
synchronize within + or - 50 nanoseconds with whatever you are using as 
a time source.  If you must boot your computer at 8:30 every morning, 
NTPD is a poor choice!


There is another "product" which will give you a "reasonable facsimile"
of the correct time in a very short time.  I've never used it. I've
forgotten its name.  Sorry about that.  I'm sure that someone here
can recall the name I've forgotten!



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Re: [ntp:questions] Using Trimble TSIP under Linux

[Richard B. Gilbert]

On 10/28/2012 6:20 PM, unruh wrote:

On 2012-10-28, Richard B. Gilbert  wrote:


Lose the "minpoll 4 maxpoll 4 "!


Well, no, standard advice for refclocks is exactly that. get the time
every 16 sec.


It may not be causing your problems but but I doubt that it's
helping matters any!

The NTP software should pick the best clock(s) from those offered!


You know what the best clock is-- the pps intervals.



NTPD will adjust the polling intervals to suit the current
conditions.  The short poll interval will correct the large errors
quickly.  The longer poll intervals will be used to "fine tune".


Not really. The ntpd poll stretching is used to minimize the network
traffic on ntp servers. That is not a problem here. Longer poll
intervals are better (up to a point) for getting the rate of the local
clock better, but it leaves the local time worse off. With pps you are
better off getting the time right. A local refclock is not the same as a
networked ntp server.




The problem is probably the input.  Unless the network is quiet, any
time obtained from the network is suspect!  When is the network quiet?
The hours from 2:00 AM to 5:00 AM local time are usually as quiet as the 
network ever gets.


I've found that a GPS Timing receiver works very well.  YMMV!


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Re: [ntp:questions] Using Trimble TSIP under Linux

[Richard B. Gilbert]

On 10/28/2012 4:33 PM, David Taylor wrote:

On 28/10/2012 16:50, Rob wrote:
[]

Sorry I have no idea how to get it to work with a raspberry pi.

I think when you have to tinker with drivers anyway, it is better
to adapt a driver from ntpd and leave out gpsd.
(unless you want to use the positioning information from the receiver
for a local app that supports gpsd)


Rob,

Thanks for your comments.  I don't /need/ gpsd, but it does seem to be
at least partially working.  I've made progress by looking at the
various Internet sources, and found someone who had recompiled my
version of Linux to include PPS support.  So now I can:

- use cgps -s to see the output from the GPS via gpsd
- configure NTP to use the type 28 driver and it sees the GPS time
- use sudo ppstest /dev/pps0 and see assert pulses coming in
   (the clear field is always 0 though, perhaps the 150
microsecond pulse is too narrow?)

but NTP never connects to the PPS source.  My NTP configuration looks like:

===
driftfile /var/lib/ntp/ntp.drift

server 127.127.28.0  minpoll 4 maxpoll 4
fudge 127.127.28.0 time1 +0.350 refid GPS  stratum 15

server 127.127.28.1 minpoll 4 maxpoll 4 prefer
fudge 127.127.28.1 refid PPS

server 192.168.0.3  minpoll 5 maxpoll 5  iburst prefer
server 192.168.0.2  minpoll 5 maxpoll 5 iburst
server 192.168.0.7  minpoll 5 maxpoll 5 iburst
pool uk.pool.ntp.org  minpoll 10  iburst
===

With apologies for the wrap:
C:\Users\David>ntpq -p 192.168.0.14
  remote   refid  st t when poll reach   delay   offset
  jitter
==

xSHM(0)  .GPS.   15 l6   16  3770.0005.971
2.103
  SHM(1)  .PPS.0 l-   1600.0000.000
   0.000
*pixie   .PPS.1 u6   32  3770.4950.041
0.035
+FEENIX  .PPS.1 u8   32  3770.5900.040
0.025
+Stamsund.PPS.1 u7   32  3770.4660.096
0.030
-server1.terrybu 158.43.192.662 u  631 10243   21.3850.887
2.009
-rilynn.me.uk193.62.22.82 2 u  601 10243   27.880   -0.849
6.440
-ntp0.sccis.net  193.62.22.74 2 u  612 10243   18.9471.405
4.130
  resntp-b-vip.lo .INIT.  16 u- 102400.0000.000
   0.000

C:\Users\David>ntpq -c rv 192.168.0.14
associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync,
version="ntpd 4.2.6p5@1.2349-o Fri May 18 20:30:57 UTC 2012 (1)",
processor="armv6l", system="Linux/3.2.27-pps-g965b922-dirty", leap=00,
stratum=2, precision=-20, rootdelay=0.490, rootdisp=2.540,
refid=192.168.0.3,
reftime=d438146b.2b1fe219  Sun, Oct 28 2012 20:30:35.168,
clock=d438146f.b3c26062  Sun, Oct 28 2012 20:30:39.702, peer=22812, tc=5,
mintc=3, offset=0.042, frequency=-44.915, sys_jitter=0.034,
clk_jitter=2.397, clk_wander=0.238


I can't see anything obviously wrong, but perhaps I'm over-tired after a
day or two trying to get this working!



Lose the "minpoll 4 maxpoll 4 "!
It may not be causing your problems but but I doubt that it's
helping matters any!

The NTP software should pick the best clock(s) from those offered!

NTPD will adjust the polling intervals to suit the current
conditions.  The short poll interval will correct the large errors 
quickly.  The longer poll intervals will be used to "fine tune".





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Re: [ntp:questions] NTP tunning for OWD measurements

[Richard B. Gilbert]

re















5ms, so the best you can say is that the real time lies between +- 2.6ms















since yo uhave no idea what the difference between outgoing and incoming















delay times is. THAT IS WHY YOU NEED GPS ON BOTH ENDS.































































Pedro































On Saturday, October 27, 2012 5:19:09 PM UTC+1, Richard B. Gilbert wrote:















On 10/26/2012 5:56 PM, pret3n...@gmail.com wrote:































Hi all, and thank you for your answers. I'm afraid I might not have































been clear about my objectives, so I'll try to explain clearer.































I'll also try and keep the lines smaller, and please, excuse me if































I make any mistakes, as english is not my native language.































































This project involves a NREN, which interconnects several institutions.































































I give up?  WHAT IS "NREN"?

















































































Please folks.  All the ">>>>>>"  conveys nothing, at least as far as I
can see.

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Re: [ntp:questions] NTP tunning for OWD measurements

[Richard B. Gilbert]

On 10/26/2012 6:47 PM, pret3n...@gmail.com wrote:

I'm sorry, I'm not following you. What delay asymmetry are you refering to?

OWAMP does rely on accurate time stamps, see 
http://www.internet2.edu/performance/owamp/index.html

If I have S1 and X1 synching to the same time reference (in this case,
the same stratum 1 server), and I do one-way delay tests between S1 and X1,
I'm expecting to find a valid measurement of the one-way delay, no?

If you're talking about the asymmetry caused by NTP assuming the one-way delay
to/from the clients is RTT/2, I'm aware of that error. And I will try to 
minimize it,
e.g., using tunnels.


On Friday, October 26, 2012 11:19:26 PM UTC+1, David Woolley wrote:

pret3n...@gmail.com wrote:








Also, I don't want to use NTP to directly measure the one-way delay, I have 
OWAMP




You can't stop it measuring the delay asymmetry!  The trouble is you

will not have any way to obtain that value, which will tend to cancel

out the asymmetry measured by your primary tool, assuming it depends on

accurate time stamps!




(more specifically perfSonar - http://www.internet2.edu/performance/pS-PS/)



to do that for me.






The page is a commercial type hype, not a technical overview of the

algorithms used, but the only way I know of measuring one way delay is

synchronise the clocks somewhat better than the acceptable measurement

error, which you can't do if the synchronisation process is vulnerable

to the effects of the same delay asymmetry.




On Friday, October 26, 2012 11:19:26 PM UTC+1, David Woolley wrote:

pret3n...@gmail.com wrote:








Also, I don't want to use NTP to directly measure the one-way delay, I have 
OWAMP




You can't stop it measuring the delay asymmetry!  The trouble is you

will not have any way to obtain that value, which will tend to cancel

out the asymmetry measured by your primary tool, assuming it depends on

accurate time stamps!




(more specifically perfSonar - http://www.internet2.edu/performance/pS-PS/)



to do that for me.






The page is a commercial type hype, not a technical overview of the

algorithms used, but the only way I know of measuring one way delay is

synchronise the clocks somewhat better than the acceptable measurement

error, which you can't do if the synchronisation process is vulnerable

to the effects of the same delay asymmetry.




On Friday, October 26, 2012 11:19:26 PM UTC+1, David Woolley wrote:

pret3n...@gmail.com wrote:








Also, I don't want to use NTP to directly measure the one-way delay, I have 
OWAMP


What is OWAMP?


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Re: [ntp:questions] NTP tunning for OWD measurements

[Richard B. Gilbert]

On 10/26/2012 5:56 PM, pret3n...@gmail.com wrote:

Hi all, and thank you for your answers. I'm afraid I might not have
been clear about my objectives, so I'll try to explain clearer.
I'll also try and keep the lines smaller, and please, excuse me if
I make any mistakes, as english is not my native language.

This project involves a NREN, which interconnects several institutions.


I give up?  WHAT IS "NREN"?



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Re: [ntp:questions] Motorola Oncore GPS as Stratum 1 source

[Richard B. Gilbert]

On 10/19/2012 11:01 PM, John Hasler wrote:

Richard B. Gilbert writes:

...not all of us can afford Microsoft to read mail...


And some us wouldn't use it if paid to do so.  However, some MUAs such
as Gnus have "format message" commands that can render such a mess
readable.



I'll be damned if I'll spend money or time on it.

If I can't read mail conveniently because a MicroSoft product sends 1200 
character lines, making it unreadable, I'll just not read it

Most people that I want to exchange mail with do not send in formats
that I cannot read.


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Re: [ntp:questions] Motorola Oncore GPS as Stratum 1 source

[Richard B. Gilbert]

On 10/19/2012 2:56 PM, E-Mail Sent to this address will be added to the 
BlackLists wrote:

Rick Jones wrote:> Richard B. Gilbert  wrote:

I suppose there's no hope of getting Microsoft to fix
  Office?


I suspect that Office automagically wraps long lines
  when displaying messages, meaning that in an "Office"
  context there is nothing perceived to be broken.


I'm certain there is a sending message format option to
  wrap lines there somewhere.



It may be so but, from time to time, someone posts something with 400 
characters and NO  or "new line"!


It may be that Microsoft  can render these lines but not all 
of us can afford Microsoft to read mail, news and/or other text 
nor should we have to!




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Re: [ntp:questions] Motorola Oncore GPS as Stratum 1 source

[Richard B. Gilbert]

On 10/18/2012 6:50 PM, Rick Jones wrote:

Richard B. Gilbert  wrote:

That's great.  I suppose there's no hope of getting Microsoft to fix
Office?


I suspect that Office automagically wraps long lines when displaying
messages, meaning that in an "Office" context there is nothing
perceived to be broken.

rick jones



That's great IF you are using some Microsoft product on both ends of the 
link.  Do I sense MONOPOLY at work?


Where is the FTC when you need them? !!!


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Re: [ntp:questions] Motorola Oncore GPS as Stratum 1 source

[Richard B. Gilbert]

On 10/18/2012 5:11 PM, Ron Hahn wrote:

-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1

On 18/10/2012 21:07, Richard B. Gilbert wrote:

On 10/17/2012 8:27 AM, Hahn, Ron wrote:

Colleagues,

I am putting together some Motorola Oncore UT+ boards to replace
my Sure boards in my ntp servers.  I am using this
http://www.tapr.org/gps_vpib.html board as the templat for the
interface circuits.  The circuit calls for a BR2325 battery which
I cannot find in the local parts store.  Is there a person on
this list with experiences of this board design that can tell me
what I can substitute for this part?  Or maybe it is not
necessary?  I am not even sure if the battery is necessary but
from my experiences the boards go from a cold start whenever
power is interrupting. One of my servers is part of the ntp pool
so I am needing the rapid recovery if the power is interrupted.
My systems are on the UPS so maybe this battery is not required?

Thanks for the helping hands,

Ron



Please use your return key!!  The first line of your message runs
right off my screen!  sixty to one hundred characters per line
seems a reasonable length to me.  Greater lengths may be difficult
for some people to read!


Richard,

I am blaming that on Microsoft office, which I sent the original email
with. I am hoping that this Thunderbird email is more wrapped to your
satisfaction.



That's great.  I suppose there's no hope of getting Microsoft to fix Office?


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Re: [ntp:questions] Motorola Oncore GPS as Stratum 1 source

[Richard B. Gilbert]

On 10/17/2012 8:27 AM, Hahn, Ron wrote:

Colleagues,

I am putting together some Motorola Oncore UT+ boards to replace my Sure boards 
in my ntp servers.  I am using this http://www.tapr.org/gps_vpib.html board as 
the templat for the interface circuits.  The circuit calls for a BR2325 battery 
which I cannot find in the local parts store.  Is there a person on this list 
with experiences of this board design that can tell me what I can substitute 
for this part?  Or maybe it is not necessary?  I am not even sure if the 
battery is necessary but from my experiences the boards go from a cold start 
whenever power is interrupting. One of my servers is part of the ntp pool so I 
am needing the rapid recovery if the power is interrupted. My systems are on 
the UPS so maybe this battery is not required?

Thanks for the helping hands,

Ron



Please use your return key!!  The first line of your message runs right 
off my screen!  sixty to one hundred characters per line seems a 
reasonable length to me.  Greater lengths may be difficult for some

people to read!

The battery you are seeking is available at Amazon.com for $3.99 U.S. 
for one battery.  Another seller is offering a package of five for $9.95 
U.S.


YMMV!

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Re: [ntp:questions] setting the time/frequency before starting ntpd to avoid slow convergence (PPS)

[Richard B. Gilbert]

On 10/12/2012 8:27 PM, gabs wrote:

On Saturday, October 13, 2012 7:25:26 AM UTC+8, Richard B. Gilbert wrote:

On 10/12/2012 6:25 PM, gabs wrote:


1. Kill ntpd if running


To what purpose???

If NTPD is running, your clock should be very close to the correct time.
  I can't see anything useful to be gained by restarting NTPD.


For cases when ntpd is running and the offset and drift are way off. Your PPS 
measurements may be invalid while ntpd is running.



Once you have your clock running, leave it running 24x365.  An

uninterruptable power supply is a good thing to have; it lets you ride

out the brown outs and drop outs.  Another good thing to have is a

gasoline powered generator for those times when the power company really

screws up!  You should know BEFORE the power goes off what your

emergency plan expects you to do..


This method is an option for setups not running 24x7 or environments where 
stable power is not available. You don't need hours to stabilize the NTP clock 
discipline, as long as the offset and frequency/drift is within acceptable 
bounds.



Please use your "Return" key!  That last line runs off the right side of 
my screen.


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Re: [ntp:questions] setting the time/frequency before starting ntpd to avoid slow convergence (PPS)

[Richard B. Gilbert]

On 10/12/2012 6:25 PM, gabs wrote:

Instead of waiting several minutes (hours?) to reach microsecond offsets, I've 
been using a chrony-like

method to set the time and frequency before starting ntpd:



It's hours!  About ten hours to get the best time the system is capable of!


1. Kill ntpd if running


To what purpose???

If NTPD is running, your clock should be very close to the correct time. 
 I can't see anything useful to be gained by restarting NTPD.


NTPD needs something like ten hours to reach a steady state with the 
best possible approximation to the correct time.  If at all possible,

run your clock and NTPD 24 X 7.  Also, keep the ambient temperature
within narrow limits if at all possible!



2. Reset the kernel flags, offset, and frequency:
  ntptime -N -s 1 -o 0 -f 0; ntptime -N -s 0
3. Set the time within a few ms. If adjtime() is used, wait for the slew to 
stop.
4. Collect PPS timestamps for 30 seconds, then run an L1 regression to estimate 
the clock frequency and offset.
5. Use the estimated frequency to set the kernel frequency and drift file
6. adjtime() the estimated offset. Wait for the slew to stop.
7. Start ntpd. Expect a few us of offset while ntpd finely adjusts the 
frequency.



Once you have your clock running, leave it running 24x365.  An
uninterruptable power supply is a good thing to have; it lets you ride 
out the brown outs and drop outs.  Another good thing to have is a 
gasoline powered generator for those times when the power company really 
screws up!  You should know BEFORE the power goes off what your

emergency plan expects you to do..

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Re: [ntp:questions] NTP client configuration

[Richard B. Gilbert]

On 9/27/2012 2:59 PM, Benjamin CABUT wrote:

Hello,

I don't car in my application to have the correct UTC time.

What I care is that all my computers share exactly the same time.
Our application is not connected to internet.
So only time I can use as a reference is local clock of one computer.


It's difficult to get multiple devices to keep a common time without a
stable reference clock. I'd suggest using a GPS timing receiver.  It 
will give you a rock solid one second per second beat that most 
computers can synchronize with.


NTPD needs about ten hours to synchronize its host down to the 
nano-second level.  Once synchronized it should stay synchronized.


If you need to turn everything off at 5:00 PM and turn it on again
at 9:00 AM, NTP is a poor choice.




I can realy tell you that my client is not sync some times!
it happen in 2 ways:
-> when I start my computers, it need arround 5 minutes to be sync, it
is a problem for me
-> when one computer has heavy operation to do, then ntp client desync

and I have offset that can be 2 seconds, and stay like this during
sereval minutes.
so It realy need a long time to ntp client to detect the big desync.

I do not want to rewrite ntp.
ntpq gives the offset between clock of client and clock of server.

As you say the best way for me is that ntp is working perfectly, but it
is not the case.
I don't know how to improve this by configuration.

So I was just wondering if I could get the offset in my software to
solve my problem...

Regards.







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Re: [ntp:questions] What exactly happens to ntpd if it is made to run and no server address is given in the ntp.conf file?

[Richard B. Gilbert]

On 9/25/2012 12:26 PM, Arpith Nayak wrote:

Could someone give me a blow-by-blow account of what happens exactly?
Also, does ntpd search for an NTP server in the network accessible by it if
no server is specified? Can we implement this functionality if not
available?

Regards,
Arpith



What problem are you trying to solve?  I don't know what NTPD will do if 
run without a time source.  I can't think of any use for such a 
configuration!



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Re: [ntp:questions] ANN: UK GPS Jamming: 24th - 28th Sept and 1st - 5th Oct 2012 - Dixie's Corner

[Richard B. Gilbert]

On 9/21/2012 9:07 AM, David Taylor wrote:

Folks,

I have received the following announcement:

_
Dates: Between 24th - 28th Sept and 1st - 5th Oct 2012

Times: 0800 -1600 GMT.

Location of MULTIPLE jammers: Multiple Land based within 5km of N52°
00.881' W003° 38.518' (SN873365 - Dixie's Corner).

Frequency: IN 24 MHz bandwidths centered on 1575.42MHz(GPS L1)
1227.60MHz(GPS L2) AND 1176.45MHz(GPS L5).

Jammers: GLOBAL POSITIONING SYSTEM (GPS) JAMMING, CW, PM

It is stressed that, as in previous exercises, Safety of Life operations
will at all times take precedence over exercise activities.
_




Don't you ever do anything else?

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Re: [ntp:questions] ANN: UK GPS Jamming: 24th - 28th Sept and 1st - 5th Oct 2012 - Dixie's Corner

[Richard B. Gilbert]

On 9/21/2012 9:07 AM, David Taylor wrote:

Folks,

I have received the following announcement:

_
Dates: Between 24th - 28th Sept and 1st - 5th Oct 2012

Times: 0800 -1600 GMT.

Location of MULTIPLE jammers: Multiple Land based within 5km of N52°
00.881' W003° 38.518' (SN873365 - Dixie's Corner).

Frequency: IN 24 MHz bandwidths centered on 1575.42MHz(GPS L1)
1227.60MHz(GPS L2) AND 1176.45MHz(GPS L5).

Jammers: GLOBAL POSITIONING SYSTEM (GPS) JAMMING, CW, PM

It is stressed that, as in previous exercises, Safety of Life operations
will at all times take precedence over exercise activities.
_




Don't you guys ever do anything else?

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Re: [ntp:questions] Testing throughput in NTP servers

[Richard B. Gilbert]

On 9/12/2012 2:34 PM, unruh wrote:

On 2012-09-12, Ulf Samuelsson  wrote:

Anyone knows if there are any available Linux based S/W to test the
throughput of NTP servers?
I.E:

packets per second?
% of lost packets
etc?

Best Regards
Ulf Samuelsson


I hope not. I can just see someone deciding to test one of the stratum 1
main servers (eg at the usno) Why in the world would you want this?



Sigh!  I'm sure it has happened and will happen again!  I'm sure that 
there are people complaining to the National Bureau of Standards or

the Naval Observatory that their time is incorrect! ;-)

If you really want time with better than micro-second accuracy, consider 
get a GPS Timing receiver. The one I bought several years

ago claimed 50 nanosecond plus or minus of the correct time.

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Re: [ntp:questions] PPS and NMEA

[Richard B. Gilbert]

On 9/10/2012 5:02 AM, Rob van der Putten wrote:

Hi there


ksprabha wrote:


Kindly let me know what is the difference between NTP with PPS and NTP
with out PPS.


NMEA can be a bit off with some GPS receivers. PPS tends to be very
accurate.



The the PPS (assuming we are talking about the Pulse from a GPS Timing 
Receiver) is specified to be within plus or minus 50 nanoseconds.





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Re: [ntp:questions] System time changes only on restarting ntpd service and query about iterating through the sources

[Richard B. Gilbert]

On 9/7/2012 11:51 AM, unruh wrote:

On 2012-09-05, Richard B. Gilbert  wrote:

On 9/5/2012 7:29 AM, unruh wrote:

On 2012-09-04, Arpith Nayak  wrote:

Hi all,
I'm running into this problem.  The system time is set to 1970 after every


your RTC is broken.


system reboot. The first time I enable ntpd it is contacting the ntp source
and getting the updated time. However it is unable to change the system


How are you starting ntpd?
What flags?


time immediately. Only after I stop the service and start it again does the
system time get changed. Has anyone else observed this behaviour? Also is
there any way to iteratively consult the various server addresses given in
the ntp.conf file?

Regards,
Arpith


On some, or many machines, the hardware clock (time of day) is sustained
by a "coin cell" battery when power is off!  Sooner or later this
battery must be replaced.  The ones I've encountered used a "CR-2013"
coin cell.  If investigation reveals that there is such a cell it will
need to be replaced every few years.  Observe the markings
on the old battery and find a battery to match it.  If power is seldom
off and is restored quickly this battery may last for three to six
years! YMMV

As I recall,the last time I needed such a battery, I purchased it for a
dollar or two at a nearby drug store.

If this does not resolve your problem, seek professional help!


Unfortunately on many systems the batter is welded into the system. It
is not user replacable. They expect you to throw out the motherboard
when the battery dies.






I've never seen such a system.  I hope I never do!  Who 
manufactured/distributed this P.O.S???



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Re: [ntp:questions] System time changes only on restarting ntpd service and query about iterating through the sources

[Richard B. Gilbert]

On 9/5/2012 4:47 PM, David Woolley wrote:

Arpith Nayak wrote:

Hi all,
I'm running into this problem.  The system time is set to 1970 after
every
system reboot. The first time I enable ntpd it is contacting the ntp
source


I was under the impression that NTP time stamps are ambiguous on a time
scale that means a system starting with a time in 1970 will never get a
correct time.


and getting the updated time. However it is unable to change the system
time immediately. Only after I stop the service and start it again
does the
system time get changed. Has anyone else observed this behaviour? Also is
there any way to iteratively consult the various server addresses
given in
the ntp.conf file?


A lot of this probably relates to the system startup scripts, not to
ntpd.  As you haven't identified the system, it is a bit difficult to be
sure what is going on.




Without knowing a bit more about the hardware and software involved it's 
difficult to diagnose.  AFAIK, there should be nothing that requires 
that your clock defaults to 1970.


If the system defaults the date to 1970, you should be to able override
the 1970 date by setting the correct year, month, day, time, etc.

If you don't restart the system frequently the date/time should not be a
big problem.  If you must restart, either set the date/time from a 
"known good" clock, or learn to live with unreliable date/time stamps.


Best practice is DON'T restart!  If you MUST restart, the startup 
scripts should get and set the date and time from a trusted source.




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Re: [ntp:questions] System time changes only on restarting ntpd service and query about iterating through the sources

[Richard B. Gilbert]

On 9/5/2012 7:29 AM, unruh wrote:

On 2012-09-04, Arpith Nayak  wrote:

Hi all,
I'm running into this problem.  The system time is set to 1970 after every


your RTC is broken.


system reboot. The first time I enable ntpd it is contacting the ntp source
and getting the updated time. However it is unable to change the system


How are you starting ntpd?
What flags?


time immediately. Only after I stop the service and start it again does the
system time get changed. Has anyone else observed this behaviour? Also is
there any way to iteratively consult the various server addresses given in
the ntp.conf file?

Regards,
Arpith


On some, or many machines, the hardware clock (time of day) is sustained 
by a "coin cell" battery when power is off!  Sooner or later this 
battery must be replaced.  The ones I've encountered used a "CR-2013" 
coin cell.  If investigation reveals that there is such a cell it will 
need to be replaced every few years.  Observe the markings
on the old battery and find a battery to match it.  If power is seldom 
off and is restored quickly this battery may last for three to six 
years! YMMV


As I recall,the last time I needed such a battery, I purchased it for a 
dollar or two at a nearby drug store.


If this does not resolve your problem, seek professional help!

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Re: [ntp:questions] Does NTP cause an abrupt/sudden change in an orphan's system time?

[Richard B. Gilbert]

On 8/8/2012 6:56 AM, Arpith Nayak wrote:

I have a server that is in the orphan mode i.e. it was not connected to the
internet (and thus the various public NTP servers) when I booted it up. Now
if I install ntpd oin this server and run it, will the first instance of
ntpd cause a sudden change in the system time as well as timestamps or does
NTP cause a slow gradual change so that it syncs up with the public server
over a period of time?

Regards,
Arpith



If the clock is seriously in error NTPD will step the clock.  If the 
clock  is very close to being correct, NTPD will adjust the speed of the
clock to make the change slowly.  I don't recall how far off the clock 
must be before NTPD will step it.  It might require as much as 10 hours

for NTPD to synchronize.  ISTR it takes a minimum of thirty minutes from
start up until it has a reasonable facsimile of the correct time.  It 
could take another nine and a half hours to get the correct time AND a 
stable clock.


It should be obvious that NTPD needs to run 24x7 for best results

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Re: [ntp:questions] WARNING: someone's faking a leap second tonight

[Richard B. Gilbert]

On 8/6/2012 8:44 AM, Dick Wesseling wrote:

In article <501d6636.9050...@gmail.com>,
Jeffrey Lerman  writes:



On Fri, Aug 03 2012 at 5:42PM, Harlan Stenn  wrote:

It looks like this recently-filed (and cryptically-named) ntpd bug might
be related to the bogus leap seconds?
http://bugs.ntp.org/show_bug.cgi?id=2246   "sys_leap is stick"



I intended to type "sticky".



Proof read before hitting "send"!  Especially if you are a poor typist. 
 I find that a "spelling checker" is a good thing to use.

Of course it won't help much if you type the wrong word!


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Re: [ntp:questions] WARNING: someone's faking a leap second tonight

[Richard B. Gilbert]

On 8/4/2012 12:28 PM, unruh wrote:

On 2012-08-04, David Woolley  wrote:

Harlan Stenn wrote:

Oh, my mistake:  I quote RFC5905 below, which is for NTPv4, which is
technically in _draft_ status - though it does seem pretty far along and
I believe current ntpd adheres to NTPv4, not v3.


The NTP code *defines* the spec, and there will be times when the


I think you mean the "ntpd reference implementation", e.g. Microsoft's
NTP code does not define the standard.


And it is a reference implimentation, not the definition. Ie, it is an
implimentation that is supposed to follow the standard. It does not
define the standard.


Also, I don't think this is the correct relationship between RFCs and
reference implementations.  An RFC specifies the protocol for a specific


I think that the reference implimentation impliments a specific rfc. Ie,
the rfc comes first.


reference implementation.  If you do more than fix bugs in the reference
implementation, you need a new RFC before it becomes the standard.


An rfc is just a request for comments. It is NOT a standard. It may
become one ( although I think none of the ntp rfcs have actually ever
become standards).






It's unlikely to become a standard until people stop tinkering with it!
It's pure hell trying to "standardize" a moving target.

The standard, when published, must satisfy meet the needs of the 
community.  It won't be easy.  We've had something that works for most 
of us for the last few years.  With a bit of luck we can have "this is 
how it works and these are the standards that a conforming 
implementation must meet".


Blood will flow before we get a standard we can all agree on. 
Hopefully, only people I don't like will be killed. ;-)



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Re: [ntp:questions] WARNING: someone's faking a leap second tonight

[Richard B. Gilbert]

On 8/1/2012 11:54 AM, Rob wrote:

steven Sommars  wrote:

I've seen no evidence of a denial of service attack, bugs are more likely.
   Several stratum one servers have been advertising LI=1 continuously for
the past month.   Others alternate between LI=0 and LI=1.
Most servers claim to run ntpd.

There are over 10 stratum one's that advertise LI=1 as of Wed Aug  1
14:18:51 UTC 2012.   Unless this changes another false leap second could
occur on August 31, 2012


When a leapsecond occurs as a result of these bits that is a bug on
its own, because leapseconds can only occur at the end of a quarter.



Does ANYONE use a stratum 10 server?  If so, how good is the time?

Could a dripping faucet do as well or better?


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Re: [ntp:questions] NTP on local networks

[Richard B. Gilbert]

On 7/31/2012 12:06 PM, unruh wrote:

One option is to install a gps receiver onto one or more of your
machines to deliver accurate time to them.

The second option is to look into "orphan" mode, which was designed for
your situation.

Your problem is probably that you are using more than one of th
emachines as the "server" and they have gotten out of sync with each
otehr so that the other machines cannot figure out which is the more
accurate time. You give no indication of what you have set up so it is
pretty hard to figure out what is going wrong.

On 2012-07-30, Will Shackleford  wrote:


We have several computers  with several different operating systems on a
local network with no radios and no internet connection.
The main goal is to keep them synchronized with each other.

One frustration I have had is that clients tend to refuse to connect to
servers on the network
that are "not good enough". I assume "not good enough" means too high a
stratum although the


stratum does not really matter (unless it is 15 or so) but disagreement
amongst the servers does matter.


error messages are not that clear.


Perhaps if you told us what they were, they would be clearer to some of
us than to you.



My current solution is to take a laptop to another room with an internet
connection, let it sit for an hour and
then bring it back to connect the local network where finally the other
computers will accept it and synchronize with it.


Questions:

How can I configure a client/peer to always accept a server as "good
enough" or atleast always accept the server
when no other server can be contacted? (please answer for any platform
below you can)


Fedora 6:
Fedora 10:
Fedora 14:
Ubuntu 11.04:
Windows XP:


How can I configure a server to always consider itself "good enough" and
report that (lie if necessary) so that any badly configured
client will still connect?(please answer for any platform below you can)


Fedora 6:
Fedora 10:
Fedora 14:
Ubuntu 11.04:
Windows XP:



Just for my own curiosity, why is just refusing to do what the operator
wants the default behavior for clients/peers? Why not always
synchronize as well as you can with whichever peers/hosts you can contact?


NTP needs a stable and accurate source of time.  Such sources are 
provided by most national governments.  In the U.S. the the National 
Bureau of Standards keeps the official clock for the U.S.  The official
time is supplied in Canada by an agency called Communications Branch, 
National Research Council.  Just about every country has it's own 
"standard" clock and they go to great lengths to ensure that all these 
clocks are accurate and stable.


How do you calibrate your atomic clock?  That's easy.  You load your 
clock into a truck with a battery pack and take your truck or your 
airplane and go to the National Bureau of Standards.  The staff bring a 
coaxial cable to your vehicle, connect it to your clock(s) input and 
zap  If you are really fanatical, you correct for the length of

the cable,  . . . .


Most of us don't go quite that far.  I, for instance, have a GPS timing 
receiver which keeps my computers marching to the same beat. It's 
overkill but I enjoyed  doing it.



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Re: [ntp:questions] NTP on local networks

[Richard B. Gilbert]

On 7/30/2012 11:47 AM, Will Shackleford wrote:


We have several computers  with several different operating systems on a
local network with no radios and no internet connection.
The main goal is to keep them synchronized with each other.

One frustration I have had is that clients tend to refuse to connect to
servers on the network
that are "not good enough". I assume "not good enough" means too high a
stratum although the
error messages are not that clear.


How is a system designated "not good enough"?

How about giving us the full and exact text of whatever message you are 
getting.


"Cut and paste"  would be best but a carefully made copy should serve.



My current solution is to take a laptop to another room with an internet
connection, let it sit for an hour and
then bring it back to connect the local network where finally the other
computers will accept it and synchronize with it.


Questions:

How can I configure a client/peer to always accept a server as "good
enough" or at least always accept the server
when no other server can be contacted? (please answer for any platform
below you can)


You can't without doing violence!

There is a fairly simple and not terribly expensive solution.

It's a GPS timing receiver!  They were available for about $100 the last 
time I looked. Can you put an antenna smaller than a hocky-puck

where it will have a "view" of the sky?

If you can,whip out your check book!  There are other time broadcasts 
that should be within a few milliseconds.  WWV broadcasts time on 
several freqencies 5MHz, 10MHz and several others. Canada and most other

countries also have a time broadcast .

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Re: [ntp:questions] losing time fast

[Richard B. Gilbert]

On 7/9/2012 2:14 PM, Fritz Wuehler wrote:

I noticed the clock on my main desktop was off by 28 minutes today and it
increased to 45 minutes. I resync'd with ntpdate manually and it has drifted
behind again about 7 minutes in the last few hours.


You do not mention the direction of the error which *may* be 
significant!  If the clock is "slow", it suggests that something may be

eating your CPU while running at high priority!

If the clock is "fast", nothing suggests itself to me!



I am using ntp version 4.2.4p7 which was installed with Slackware on Linux
kernel 2.6.29.6. Until today the clock on this system has always matched the
clocks of the other machines on my network. The system has been running for
several years essentially unchanged.

The only thing that changed (that I know of) is I added a new machine to my
network recently. Its clock matches all the other clocks. I don't see any
unusual messages from ntpd in my log or messages files on the system with
the problem. One system has problems, all others appear to be fine and have
synchronized clocks.

I realize this isn't much information but I don't know what to look for. Can
anyone tell me how to troubleshoot this? Thank you.




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Re: [ntp:questions] ntpq -c

[Richard B. Gilbert]

On 5/21/2012 9:58 AM, Luc Roels wrote:









Hi,

I am an NTP newbie but have been asked to debug a problem in our system. Our software 
uses the output of the ntpd -c "rv assid" 127.0.0.1 to determine if the NTP 
server is reachable and if it is synced or not by inspecting the filtoffset line.

On some machines this command takes up to 3 minutes. What is the reason it 
takes so long? Can anything be done do shorten this or is this normal behaviour?

Thanks for your help,

Luc Roels


Is your return key broken?  The lines of your message run off the right 
side of a 22" screen!


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Re: [ntp:questions] ntpd interfacing with newsyslog/logrotate?

[Richard B. Gilbert]

On 4/22/2012 6:48 PM, David Lord wrote:

Richard B. Gilbert wrote:

On 4/22/2012 7:15 AM, David Lord wrote:

A C wrote:

Does anyone familiar with NetBSD know if there's a particular
configuration for newsyslog that will allow the main ntpd log to
rotate on a regular basis? It seems that ntpd loses track of its log
file during a rotate and stops updating.


NetBSD-5.1-Stable on i386 here. My ntp.log has rotated
without since around 1998 when running NetBSD-1.5x but

^

Without what? Please remember to proofread before hitting send!


"without problem"

I did check before hitting send.

My screen takes too long to refresh and keyboard repeats
are sometimes delayed. Remember this is 2012 and everything
has improved.


David


Please do not blame your screen!  It's much more likely that your 
computer (CPU) is too busy.


Two possible fixes occur to me:
1.  Get a faster CPU
2.  Kill some of the junk that's eating your CPU.

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Re: [ntp:questions] ntpd interfacing with newsyslog/logrotate?

[Richard B. Gilbert]

On 4/22/2012 7:15 AM, David Lord wrote:

A C wrote:

Does anyone familiar with NetBSD know if there's a particular
configuration for newsyslog that will allow the main ntpd log to
rotate on a regular basis? It seems that ntpd loses track of its log
file during a rotate and stops updating.


NetBSD-5.1-Stable on i386 here. My ntp.log has rotated
without since around 1998 when running NetBSD-1.5x but

  ^

Without what? Please remember to proofread before hitting send!



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Re: [ntp:questions] where is the most authoritative NTP documentation?

[Richard B. Gilbert]

On 4/2/2012 5:20 PM, E-Mail Sent to this address will be added to the 
BlackLists wrote:

Alby VA wrote:

Aside from the most authoritative NTP Docs,
   where is an NTP 101 Doc on understand the basics?
  Not specially with running NTP, but with grasping
   time concepts, PPS, Stratum-0 Devices, etc?
  In short, where are the Cliff Notes
   on the Ph.D lecture of Time and Time tracking devices?




  Has Sections on "Basic Concepts" and "How NTP Works".
   {Although I found "In the Belly of the Beast"
(algorithm descriptions) more interesting.}


A quick google finds:




Professor David Mills has written a book on NTP, which he more or less 
invented.  It's a text intended for a college course and fairly 
expensive.  I get the idea that a background in control systems theory 
might be a big help in understanding NTP.


If you just want to install it and keep a bunch of computers marching to 
the beat of an "atomic clock" somewhere, that's what it's for!


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Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?

[Richard B. Gilbert]

On 3/22/2012 5:54 PM, David Lord wrote:

unruh wrote:

On 2012-03-22, David J Taylor 
wrote:

"unruh"  wrote in message
news:xLHar.38386$iq1.34...@newsfe18.iad...



[]

Measure what? Why do you think that ntp reporting the offset with an
extra three decimal points would allow you to measure anything? What in
your mind would you expect to see in that output that would allow
you to
"measure" something that would tell you that the -19 was wrong?
Remember
ntpd DID measure something in order to determine that -19. What do you
think the extra decimal places would give you?

Most likely I would be looking at a histogram of the reported
offsets, and see whether it was gaussian, flat, or whatever, and how
wide. I might learn something from that.


No. Not if it is just noise.

Others have reported precisions better than -19, and also have a need
for greater reporting precision.


That is a valid issue.


I have servers currently with precision= of 18, 19, 20 but not
scanned back in history more than today. The value varies, with
temperature and system load which causes local temperature
variations. The precision values vary and are just way points.

With precision 20. I don't really need an extra decimal place
but in a previous life was used to throwing away two results
from five or more if from a greater number of samples.

My standard pc hardware can't do any better.


David



There seems to be an impression out there that I'm trying to show
something is wrong - I'm not. I suggested an enhancement so that the
precision of ntpq matched that of the loopstats. That's all.


precision is not accuracy.
In science we teach students not to report unwarranted precision-- the
precision should reflect the accuracy of the measurements. We keep
getting measurements to the mm and reported precision to angstoms
because that was what the calculator spit out. I am not averse to
reporting with a precion maybe up to a factor of 10
better than the accuracy, but any more is just silly and misleading (as
you are demonstrating in believing that a greater precision would convey
some extra information.

David


I remember this one from thirty or more years ago:
"Measure with micrometer, mark with chalk, cut with axe!"


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Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?

[Richard B. Gilbert]

On 3/21/2012 7:39 PM, Alby VA wrote:

On Mar 21, 7:36 pm, unruh  wrote:

On 2012-03-21, Alby VA  wrote:










On Mar 21, 3:55?pm, unruh  wrote:

On 2012-03-21, David J Taylor  wrote:



"unruh"  wrote in message
news:itmar.5841$yd7@newsfe15.iad...
[]

But -19 is about 2 microseconds if I understand it correctly. That means
that the clocks are incapable of delivering more than about 2
microseconds of accuracy. What is you ?that last decimal digit of
accuracy in the offset is thus pure noise-- dominated by clock reading
noise. Why is it important for you then?



When I can see the decimal places, then I will know whether the precision
estimate is reasonable. ?Just getting values such as -1, 0, 1 microseconds
is insufficient to make that call.



And how will the extra decimals help? The -19 was determined by making
successive calls to the clock and seeing how much it changed between
successive readings. That gives a good estimate of how long it takes to
make a call to the clock. Any precision in the answer beyond that is not
accuracy. I could give you the time to 6 decimal places, each one of
the diffetent, but the last 5995 just being garbage (random numbers)
Would that tell yo uanything?
If for some reason you do not believe ntpd's estimation of your clock
accuracy, develope a better algorithm for determining it. It is a bug is
ntpd is reporting an accuracy much worse than it actually is.



Ie, you have no data to make that call even if you get more digits.



David



unruh:



   My take is the precision output might say your device is -19 so you
know its
accuracy is around 2/microseconds. But the offset several decimal
places
allows you to see its ever changing accuracy within that 2/microsecond
band


But that is not accuracy. That is presumably (if that -19 is accurate
and not a bug) is simply noise. If your measurement technique is only
good to 2us, then any additional precision is just noise. It may be fun
to see the noise, but not terribly useful. If it is not noise, then that
-19 is wrong, and one has a bug in the determination of the accuracy of
the clock reading.


to a greater detail than just -1, 0, or 1 microseconds. I guess its
just a matter
of getting more granular details for cool MRTG charting. :)


It could well be that charting looks better without just bands on the
page. But is it worth it if that detail is just junk? It certainly is
not great art.



  It there any good way to determine what is noise and what isn't?




Try comparing against a known good source!  Time from sources on the 
internet is almost always noisy!  If you must use internet sources
try to query them between 0200 and 0400 local time; the net will be as 
quiet as it's likely to get!


Time/Frequency Standards are not cheap!  If you can afford one, the 
National Bureau of Standards, in the U.S., will be happy to calibrate it 
for you.  Governments of countries other than the U.S. should have

similar facilities.


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Re: [ntp:questions] PSYCHO PC clock is advancing at 2 HR per second

[Richard B. Gilbert]

On 3/20/2012 2:59 PM, unruh wrote:

On 2012-03-20, David J Taylor  wrote:

"unruh"  wrote in message
news:d13ar.7952$gv1.7...@newsfe12.iad...
[]

It is really really hard to imagine any gps device doing that.


Yes, I agree, and yet what just popped up in my mail box but a reference
to:

   "an inexplicable 1 second slip of 3 GPS based NTP time sources".

I have, of course, asked for more details!


A one second slip I could understand-- eg Gamin 18x reporting over 1


Gamin???  Perhaps you meant to write "Garmin"!



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Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?

[Richard B. Gilbert]

On 3/20/2012 3:45 AM, David J Taylor wrote:

Any chance of getting bug 2164 moving? "Greater precision needed for
ntpq offset report".

http://bugs.ntp.org/show_bug.cgi?id=2164

While I'm asking, nothing seems to have happened with bug 1577 in over
18 months. "Request that SNMP support be added for the Windows port"

http://bugs.ntp.org/show_bug.cgi?id=1577

I have made both of these "enhancement" level, which may be why they are
stuck. Should I boost the importance?

Thanks,
David


Since this is an "all volunteer" service, the fastest, and maybe the 
only, way to get this enhancement is to write the code yourself!  If you 
lack programming skills you could try paying someone to do it.


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Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?

[Richard B. Gilbert]

On 3/20/2012 3:45 AM, David J Taylor wrote:

Any chance of getting bug 2164 moving? "Greater precision needed for
ntpq offset report".

http://bugs.ntp.org/show_bug.cgi?id=2164

While I'm asking, nothing seems to have happened with bug 1577 in over
18 months. "Request that SNMP support be added for the Windows port"

http://bugs.ntp.org/show_bug.cgi?id=1577

I have made both of these "enhancement" level, which may be why they are
stuck. Should I boost the importance?

Thanks,
David


Since this is an "all volunteer" service, the fastest, and maybe the 
only, way to get this enhancement is to write the code yourself!  If you 
lack programming skills you could try paying someone to do it.


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Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?

[Richard B. Gilbert]

On 3/20/2012 3:45 AM, David J Taylor wrote:

Any chance of getting bug 2164 moving? "Greater precision needed for
ntpq offset report".

http://bugs.ntp.org/show_bug.cgi?id=2164

While I'm asking, nothing seems to have happened with bug 1577 in over
18 months. "Request that SNMP support be added for the Windows port"

http://bugs.ntp.org/show_bug.cgi?id=1577

I have made both of these "enhancement" level, which may be why they are
stuck. Should I boost the importance?

Thanks,
David


Since this is an "all volunteer" service, the fastest, and maybe the 
only, way to get this enhancement is to write the code yourself!  If you 
lack programming skills you could try paying someone to do it.


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Re: [ntp:questions] ignore this - testing

[Richard B. Gilbert]

On 3/16/2012 3:17 PM, Ron Frazier (NTP) wrote:

Ignore this. Testing, is this thing on?

Hadn't noticed any messages for 12 hours. Just checking to make sure
it's working.

Ron




Please learn patience!  It's a low volume news group!  There are 
occasional days when there are no messages at all!  A significant 
proportion of the messages posted are off topic!  Let's try to keep them 
to a minimum!


I've been reading this group for eight to ten years now.  Most on-topic 
posts will be answered in a timely fashion.


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Re: [ntp:questions] ESR looking for good GPS clocks

[Richard B. Gilbert]

On 3/6/2012 3:59 PM, Ron Frazier (NTP) wrote:

On 3/6/2012 3:28 PM, Rob wrote:

Ron Frazier (NTP) wrote:

I looked at that chart 3 times and even zoomed in on it. It looks like
to me that the vertical scale is in ns.

Look again. You can find an example m and n in the word Garmin in the
top caption.


Gulp. OK, I guess I have to eat some crow for that. I apologize for the
error. Weirdest looking "m" I've ever seen. But, now that you mention
it, it does appear that the vertical scale is in milliseconds. So, what
you and David are saying is that there is a 170 ms variance in the start
time of the NMEA sentences for the Garmin. Does it use a SIRF chipset?
Is this variance intrinsic to all GPS's?

I looked in the manual for the Garmin and for the Trimble Resolution T.
All they say is that the NMEA is referenced to the PPS, but they don't
give a spec for the delta between them. Of course, my GPS has no PPS,
but the NMEA output has to be referenced to something!

Sincerely,

Ron




It would appear that your GPS receiver is NOT a timing receiver.

Any GPS receiver knows what time it is.  Not all receivers are equipped
to output the time in any usable form.  A timing receiver generally has
a Pulse Per Second (PPS) output.  One edge marks the start of a second.
See your manual to determine WHICH edge, rising or falling, is used.


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Re: [ntp:questions] Previous Question [ Leap second indication (Linux NTPD specifically)]

[Richard B. Gilbert]

On 3/6/2012 9:30 AM, Phil Fisher wrote:

Dear Moderator
Due to an oversight on my part I would be grateful if you could remove the 
signature (like that below) from the previous post and NOT BOTHER POSTING THIS 
RESPONSE. (Or remove the post and ask me to do it again sans signature part)

If this is not possible please accept my apologies and I will be more careful 
in future. *grovel*


AFAIK there is no "moderator".

Please stop groveling before someone trips over you!  ;-)

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Re: [ntp:questions] got the Sure GPS on order, how do I program it

[Richard B. Gilbert]

On 3/5/2012 10:04 PM, Ron Frazier (NTP) wrote:

Hi all,

OK, I went and ordered the Sure GPS board, cables, box, hardware, etc. I
even bought a cheapie soldering station for $ 20. Other than the
mechanical setup which I can figure out and the patches which David
Taylor has documented, I need to know how to program the unit when it
comes.

Specifically, can someone tell me how to:

* change the baud rate
* change which sentences are output
* change the update interval
* enable waas, if that matters for timing
* set fixed location mode, if available
* restore nav mode
* do a warm restart
* do a cold restart
* do a reset to factory defaults
* save the settings to flash or backup memory so I don't lose them when
it's powered off
* if possible, output only the GPZDA sentence

* Any other magic you think I should know.

The manual seems to be missing most of these details. As always, any
help is appreciated. Thanks in advance.



The fact that the manual is missing details could be explained in at 
least two ways:

1. You can't change the baud rate, select sentences, etc, etc.
2. The author of the manual thinks the "how to" is obvious!

Good luck.  I'm afraid the you will need it!


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Re: [ntp:questions] Purpose of a leap second file?

[Richard B. Gilbert]

On 3/4/2012 3:37 PM, unruh wrote:

On 2012-03-04, John Hasler  wrote:

nemo_outis writes:

It was specifically chosen, not because of its deep significance as a
'universal physical constant', but specifically to make the 'new'
second very close to the old 'earth-rotation' second.


But not exact.  Can't be: the rotation is not stable.  I'm not
advocating the elimination of leapseconds: just a cessation of the
practice of treating them as if they were corrections of errors in the
atomic clocks.  Let the clocks run on TAI (and so record time stamps) and
then look up and insert leapseconds as needed for display.


Nor is the measurement of the transition of the Caesium atom stable. In
fact the best clocks are no longer those. No clocks are "stable" They
all have variation and inaccuracies in measurement of them. That atomic
clocks now happen to more stable than the earth's rotation is an
accident of history, and in future there may well be other even better
clocks, and the second will get redefined again.
If you want your clock to run on TAI, let it. But for most of the
population, time is something used to organize your days. And they will
become more important again as energy becomes so expensive that people
will not have lights on at night, except in special cases. To organize
the day, the sun is pretty important.

But if you want to measure time with TAI, go ahead. Noone is stopping
you. It is just when you claim that your religion is the one and only
true religion and everyone should comply with the church of the TAI that
people get a bit upset.



Joe Average will almost certainly fail to notice. He is concerned about
getting to work on time, and getting paid for the hours he works.  He 
also cares that television shows start at well known and predicable times.


The physicist, OTOH, needs a very precise time and one that can be 
communicated to other physicists!


I don't see any reason why Joe and the physicist can't use the same
seconds, minutes, hours, and days.  Joe can certainly live with an 
occasional leap second or leap minute.



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Re: [ntp:questions] semi OT - GPS receiver for BMW automobile on EBay

[Richard B. Gilbert]

On 3/2/2012 9:55 AM, Ron Frazier (NTP) wrote:

Hi all,

 From my previous threads you know I've been considering upgrading my
GPS receiver for NTPD. I found this GPS receiver module for BMW
automobiles. I wouldn't know what to do with it if I bought it, but I
thought it was interesting. There are a few of these on EBay, hopefully
not stolen. I think one of the ads mentioned the name Trimble.

http://www.ebay.com/itm/BMW-GPS-RECEIVER-NAVIGATION-MODULE-E38-740-750-E39-528-530-540-M5-E46-323-328-X5-/200699337078?pt=Car_Audio_Video&vxp=mtr&hash=item2eba9cd976


Price for this one, $ 63 plus shipping.

Sincerely,

Ron




Don't buy it!

There are two kinds, at least, of GPS receivers.  The type you need
is a GPS TIMING RECEIVER.  It's optimized to deliver accurate time.

The other kind is a navigation receiver.  It is optimized for position.

Both kinds know both the time and the the position, it's the 
presentation that counts.  A timing receiver will have Pulse Per Second 
(PPS) output with one edge of the pulse being within something like +/- 
fifty nano-seconds of the time written out in full.


The navigation receiver outputs your current latitude, longitude, and 
elevation. Connect it to a computer with with the proper software and

the computer will display a map with "You are here!" and an arrow symbol.

With the proper software you may be able ask your computer "Where is the 
nearest hospital?" or "Where is the nearest Chinese restaurant?"




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Re: [ntp:questions] how do you like the Trimble Resolution T

[Richard B. Gilbert]

On 3/1/2012 7:43 PM, Ron Frazier (NTP) wrote:

On 2/29/2012 6:12 PM, Chris Albertson wrote:

On Wed, Feb 29, 2012 at 2:29 PM, Bruce Lilly
wrote:

On Wed, 29 Feb 2012 14:16:23 +, Ron Frazier (NTP) wrote:


Other than the Sure board which has been mentioned, are there any other
modern, hi sensitivity, timing GPS's which cost less than $ 100. Many
of the ones mentioned seem to be older technology like this Trimble.

Don't worry. Even the UT+ which is well over ten years old is
fantastically good compared to what NTP needs. It has better specs
then many newer units and for timing, I'd say better specs then MOST
new units. $100 is a good budget. You can buy a $25 antenna and a
$20 GPS receiver and some cables and a power supply. I can safely
say that anything with the "trimble" name on it, if it was designed
for timing is almost "overkill" for use with NTP.

As long as it is a timing (not a nav) GPS and you plu the PPS into a
real serial port (not USB) you will be good to go with accuracy as
good as NTP can handle. But those are importent: (1) timing not nav
and (2) real rs232 serial. Once you have those two the rest is just
personal preferences and what you were about to find on eBay that day.

Now if you needs included precision timing (something NTP can't do)
and you cared about nano and pico seconds and frequency standards at
the 1E-13 level then yes things that NTP can't notice become
important.

The lowest cost, good units are the UT+ and then search eBay for 26dB
antenna. And yo'll find a bullet shape white one. These will fit on
a standard American 3/4" iron pipe flange with 4 bolts. That would
be the lowest cost profesional level setup and will run with the PPS
at about 50nS (1 sigma) But there are many other good setups.
Don't worry about if they are "new" tech. It's like worrying if a
1968 Chevy Corvett is fast enough to get you to work in the morning.


Chris Albertson
Redondo Beach, California


Chris,

Thanks for all the info. You've just about convinced me that, if I buy
another unit other than my USB BU-353, it should be a Motorola Oncore
UT+ or the Trimble Resolution T, or another Trimble, depending on
availability. So, that brings up even more questions. I have each of the
following questions for each of these units:

A) You said it has to be a timing GPS. How do you tell? I haven't seen
that term in any of the data sheets.


GPS comes in, at least, two flavors!  One is timing, another is 
navigation.  Both types can tell you the position of your antenna and

both can tell you what time it is.  The difference is subtle!

The timing flavor generally has a Pulse Per Second (PPS) output. One 
edge of the pulse (rising or falling) marks the second.  The designated

edge is specified to be within, typically, 50 nanoseconds.


B) How would I program the unit? I prefer to change the baud rate to at
least 57,600 and set the NMEA sentence for GPZDA only or GPGGA only.


You read the manual!  If there's no manual, buy a GPS that comes with a 
manual!!




C) Is documentation readily available for the unit?


Ask Trimble for a copy! If your request is refused or ignored, your
question is answered.  If they tell you that a manual is $xx, you send
them a check for the specified amount together with your request.  Don't
forget to tell them where to send it!


D) Would it need a firmware update and is that even possible for these
older units?


You would have to ask the manufacturer or vendor to answer that question!



E) What accessories would I need to get it going and are they available?
Antenna? Specialty cables? Power supply? Connectors?

F) I really don't prefer to put the unit or antenna outdoors for two
reasons. There is the issue of plugging the hole in the wall or window.
Also, masts and wires can be a lightning hazard, particularly in GA. We
have the 2nd highest incidence of lightning in the US. Ham radio
equipment incurs similar risks.


No "mast" is required!  I put my antenna on top of a "Leaf Guard" (TM) 
rain gutter.  You could probably put it in your attic.  You might be 
able to put it under your pillow or on your desk.





So, would these units, with the recommended antenna, be capable of
working indoors?

Any other random data I need to know about working with older equipment?

Sincerely,

Ron




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Re: [ntp:questions] how do you like the Trimble Resolution T

[Richard B. Gilbert]

On 2/29/2012 12:45 AM, Ron Frazier (NTP) wrote:

Hi all,

Is anyone using the Trimble Resolution T GPS for timing? I was looking
at an ad for one on ebay. For my purposes, any accuracy under 1 ms is
great. I don't have to have 15 ns. Of course, smaller numbers are always
better. Is this device hard to setup and program for PPS and use with
NTPD? What accessories are needed?

This is what the ad says is included:

quote on ->

The Resolution T Starter Kit provides everything you need to start
integrating the module into your application. The kit includes an
active, external 5-VDC Bullet-style antenna
,
50 feet of RG-59 cable, and an AC/DC power adapter. The starter kit
enclosure includes a mother board that provides serial output, and a
serial interface cable. A reference manual and monitor programs are
provided on CD-ROM.

<- quote off

I notice the unit only tracks 12 satellites and has 141 dbm sensitivity,
which seems to be less than some units. Is that a problem?


ISTR that only three satellites are required to determine the location 
of your antenna. Once this position is accurately known, you can live 
with a single satellite.


The last time I heard there were something like 27 GPS satellites in
service.  There are usually something like 8 satellites above the 
horizon.  Enough for most purposes!






Finally, what is sawtooth correction?

Sincerely,

Ron




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Re: [ntp:questions] Change poll interval at runtime?

[Richard B. Gilbert]

On 2/26/2012 6:20 PM, unruh wrote:

On 2012-02-26, Richard B. Gilbert  wrote:

On 2/26/2012 12:55 AM, Ron Frazier (NTP) wrote:

On 2/25/2012 5:05 PM, A C wrote:

On 2/25/2012 13:09, Richard B. Gilbert wrote:

On 2/25/2012 1:20 AM, A C wrote:

On 2/24/2012 21:26, A C wrote:

Is it possible to change the polling interval of one or more
associated
servers at runtime? It seems like I should be able to run:

ntpq -c "writevar&associd hpoll=N" or is it ppoll?



Actually, I should have been more specific and say change the minimum
polling interval. In other words, be able to adjust the conf file's
minpoll flag at runtime instead of restarting.


What problem are you trying to solve?

NTPD does a pretty good job of adjusting itself most of the time.

Short poll intervals are useful when correcting large errors.
Long poll intervals allow NTPD to make small corrections very
accurately.


The idea was to bump up the minimum poll interval after ntpd has been
running for a day or so to something more kind to the remote servers
because the refclock is holding the remote servers clamped to 64
seconds. If I set minpoll in the config file, then ntpd's start up
takes a long time because of a long poll interval. If I don't set the
minpoll, then ntpd doesn't do "a pretty good job" because it clamps
the polling interval.



I've noticed the same thing. You could try what I'm doing, although I'm
still testing for the best configuration.

# GPS Lines
server 127.127.20.5 prefer minpoll 3 maxpoll 6 mode 72
fudge 127.127.20.5 time2 0.3100 refid GPS1

# Internet server lines
# NIST New York
server nist1-ny.ustiming.org minpoll 8 maxpoll 13

# other internet server lines similar

Sincerely,

Ron



NTPD adjusts the poll interval dynamically.  Just because MINPOLL=4 does
not mean that the poll interval is "stuck" there.  Give NTPD a
rock solid 1 second per second source it will ramp up the poll interval
to 1024 seconds.  Those "rock solid" ticks can frequently be found
1:00AM to 5:00AM local time.  The net quiets down and NTPD takes
shameless advantage.

If you really want good time and can afford a GPS *timing* receiver
that's the way to do it.  The last I heard, you could get a timing
receiver for $100 -- $300.


Try $35. The Sure gps is a "timing receiver" in that it has a PPS pulse
with a 20ns or so rise time, and probably comparable accuracy.
If you want a receiver which a) does a location survey and then uses
that location to derive the time even from a single sattelite, b) tells
you what the sawtooth correction is
(which may be what you think of as a timing receiver) then that is in
the range you mention. Mind you if you are feeding a computer, you
cannot actually get that ns level time accuracy into your system, since
interrupts take 1-10us to be processed.




ANY GPS receiver knows what time it is but the navigation receivers
give priority to location.  Timing receivers give priority to delivering
the correct time.


Unfortunately most gps may know what the time is but they keep it
secret. You need to look for a PPS output to get the time out from the
receiver.





There are two types of GPS receiver, timing and navigation.  The 
difference is that the navigation receiver is optimized to calculate and 
report latitude, longitude, and elevation with the time being an

afterthought.

The timing receiver is designed to report the date-time and the location 
is available as an afterthought!  The position of the receiver is 
determined by a "site survey".  Once the location is known with the

desired accuracy, the time at the site can be easily determined.


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Re: [ntp:questions] Change poll interval at runtime?

[Richard B. Gilbert]

On 2/26/2012 6:20 PM, unruh wrote:

On 2012-02-26, Richard B. Gilbert  wrote:

On 2/26/2012 12:55 AM, Ron Frazier (NTP) wrote:

On 2/25/2012 5:05 PM, A C wrote:

On 2/25/2012 13:09, Richard B. Gilbert wrote:

On 2/25/2012 1:20 AM, A C wrote:

On 2/24/2012 21:26, A C wrote:

Is it possible to change the polling interval of one or more
associated
servers at runtime? It seems like I should be able to run:

ntpq -c "writevar&associd hpoll=N" or is it ppoll?



Actually, I should have been more specific and say change the minimum
polling interval. In other words, be able to adjust the conf file's
minpoll flag at runtime instead of restarting.


What problem are you trying to solve?

NTPD does a pretty good job of adjusting itself most of the time.

Short poll intervals are useful when correcting large errors.
Long poll intervals allow NTPD to make small corrections very
accurately.


The idea was to bump up the minimum poll interval after ntpd has been
running for a day or so to something more kind to the remote servers
because the refclock is holding the remote servers clamped to 64
seconds. If I set minpoll in the config file, then ntpd's start up
takes a long time because of a long poll interval. If I don't set the
minpoll, then ntpd doesn't do "a pretty good job" because it clamps
the polling interval.



I've noticed the same thing. You could try what I'm doing, although I'm
still testing for the best configuration.

# GPS Lines
server 127.127.20.5 prefer minpoll 3 maxpoll 6 mode 72
fudge 127.127.20.5 time2 0.3100 refid GPS1

# Internet server lines
# NIST New York
server nist1-ny.ustiming.org minpoll 8 maxpoll 13

# other internet server lines similar

Sincerely,

Ron



NTPD adjusts the poll interval dynamically.  Just because MINPOLL=4 does
not mean that the poll interval is "stuck" there.  Give NTPD a
rock solid 1 second per second source it will ramp up the poll interval
to 1024 seconds.  Those "rock solid" ticks can frequently be found
1:00AM to 5:00AM local time.  The net quiets down and NTPD takes
shameless advantage.

If you really want good time and can afford a GPS *timing* receiver
that's the way to do it.  The last I heard, you could get a timing
receiver for $100 -- $300.


Try $35. The Sure gps is a "timing receiver" in that it has a PPS pulse
with a 20ns or so rise time, and probably comparable accuracy.
If you want a receiver which a) does a location survey and then uses
that location to derive the time even from a single sattelite, b) tells
you what the sawtooth correction is
(which may be what you think of as a timing receiver) then that is in
the range you mention. Mind you if you are feeding a computer, you
cannot actually get that ns level time accuracy into your system, since
interrupts take 1-10us to be processed.




ANY GPS receiver knows what time it is but the navigation receivers
give priority to location.  Timing receivers give priority to delivering
the correct time.


Unfortunately most gps may know what the time is but they keep it
secret. You need to look for a PPS output to get the time out from the
receiver.



ALL GPS receivers know both the time and the latitude and longitude. 
The navigation receivers are optimized for use as navigation device

while the timing receivers are optimized to deliver time.

Typically, a timing receiver has a pulse per second output, one edge of 
which is accurate to within about 50 nanoseconds.  In order to get this

accuracy, it is necessary to do a "site survey" which establishes
the position of your GPS receiver's antenna.  Once you know the position
of your antenna you can calculate the time.  This is "overkill" for most 
people.  If you need something to happen simultaneously in New York 
City, and in Los Angeles, GPS timing can get you to within

~50 ns.

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Re: [ntp:questions] Change poll interval at runtime?

[Richard B. Gilbert]

On 2/26/2012 12:55 AM, Ron Frazier (NTP) wrote:

On 2/25/2012 5:05 PM, A C wrote:

On 2/25/2012 13:09, Richard B. Gilbert wrote:

On 2/25/2012 1:20 AM, A C wrote:

On 2/24/2012 21:26, A C wrote:

Is it possible to change the polling interval of one or more
associated
servers at runtime? It seems like I should be able to run:

ntpq -c "writevar &associd hpoll=N" or is it ppoll?



Actually, I should have been more specific and say change the minimum
polling interval. In other words, be able to adjust the conf file's
minpoll flag at runtime instead of restarting.


What problem are you trying to solve?

NTPD does a pretty good job of adjusting itself most of the time.

Short poll intervals are useful when correcting large errors.
Long poll intervals allow NTPD to make small corrections very
accurately.


The idea was to bump up the minimum poll interval after ntpd has been
running for a day or so to something more kind to the remote servers
because the refclock is holding the remote servers clamped to 64
seconds. If I set minpoll in the config file, then ntpd's start up
takes a long time because of a long poll interval. If I don't set the
minpoll, then ntpd doesn't do "a pretty good job" because it clamps
the polling interval.



I've noticed the same thing. You could try what I'm doing, although I'm
still testing for the best configuration.

# GPS Lines
server 127.127.20.5 prefer minpoll 3 maxpoll 6 mode 72
fudge 127.127.20.5 time2 0.3100 refid GPS1

# Internet server lines
# NIST New York
server nist1-ny.ustiming.org minpoll 8 maxpoll 13

# other internet server lines similar

Sincerely,

Ron


NTPD adjusts the poll interval dynamically.  Just because MINPOLL=4 does 
not mean that the poll interval is "stuck" there.  Give NTPD a

rock solid 1 second per second source it will ramp up the poll interval
to 1024 seconds.  Those "rock solid" ticks can frequently be found
1:00AM to 5:00AM local time.  The net quiets down and NTPD takes
shameless advantage.

If you really want good time and can afford a GPS *timing* receiver 
that's the way to do it.  The last I heard, you could get a timing 
receiver for $100 -- $300.


ANY GPS receiver knows what time it is but the navigation receivers
give priority to location.  Timing receivers give priority to delivering
the correct time.


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Re: [ntp:questions] Frequency Offset

[Richard B. Gilbert]

On 2/25/2012 2:31 AM, David J Taylor wrote:

"unruh"  wrote in message
news:l9S1r.3578$py5.1...@newsfe09.iad...
[]

The problem is that the relevant temperature is not the room
temperature, but the temperature inside the box at the crystal. That
temp variation is dominated by computer use, not outside air
temperature. Thus if one machine was coasting along, and the other was
working flat out, the temp variation witll be 10s of degrees C, even if
the outside air temp was constant.


Yes, the computer use is important, but the PCs I have as prime
startum-1 servers have a constant load, so the variation in room
temperature dominates.


Also, different crystals have different sensitivities, it is true.
Anyway ,my comment stands that his 500PPM was not because of tempreture
problems.


Yes, it's one I did not disagree with. What was remarkable to me was
that, given a constant load, three different PCs showed such a variation
in frequency. One with about 2 ppm, one with 0.3 ppm, and one with 0.025
ppm. All crystals are not created equal!

[]

On linux of a few years ago (I do not know if it has been fixed, but
indirect observations suggests it has) the calibration of the system
clock at bootup was problematic and the rate of the system would vary by
100PPM from one bootup to the next. Ie, ntpd would find its remembered
clock rate out by 100PPM. It would then take many hours to settle down
to its usual us offsets. (see graph near the bottom of page on
www.theory.physics.ubc.ca/chrony/chrony.html). This was driving it from
a GPS PPS clock with a poll level of 4. With a poll level of 6 to 10 for
a network server, the time scale will be longer by a lot (in fact it
would probably exceed the 500PPM limit and also suffer steps in the
clock as it exceeded 128ms offset).

That yours settled down quickly in your situation does not mean that
ntpd always settles down nicely and quickly.


Well, I've not seen the behaviour you observed, on any on my FreeBSD or
Windows systems. The ntp.drift file is honoured at startup, and not
tampered with until NTP has been up for one hour. Perhaps if you were
repeat your test with a more modern NTP and operating system you would
get a different result? But I don't think that anyone is claiming that
you will get microsecond-level offset within minutes of operation from
boot.



Get ready for a shock.  NTPD needs thirty minutes or more to get a 
reasonable facsimile of the correct time.  To get the microseconds 
right, NTPD needs more like ten hours!  It's not a very good fit for 
running 9AM to 5PM.  You set it running and leave it running 24x7!


If you are constrained to run 9:00AM to 5:00PM you may wish to check out 
a program called "CHRONY" or something like that.  It has much faster 
convergence.  I suspect that you will sacrifice something for that speed!


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Re: [ntp:questions] Change poll interval at runtime?

[Richard B. Gilbert]

On 2/25/2012 1:20 AM, A C wrote:

On 2/24/2012 21:26, A C wrote:

Is it possible to change the polling interval of one or more associated
servers at runtime? It seems like I should be able to run:

ntpq -c "writevar &associd hpoll=N" or is it ppoll?



Actually, I should have been more specific and say change the minimum
polling interval. In other words, be able to adjust the conf file's
minpoll flag at runtime instead of restarting.


What problem are you trying to solve?

NTPD does a pretty good job of adjusting itself most of the time.

Short poll intervals are useful when correcting large errors.
Long poll intervals allow NTPD to make small corrections very accurately.

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Re: [ntp:questions] Frequency Offset

[Richard B. Gilbert]

On 2/23/2012 9:20 PM, Alby VA wrote:

On Feb 23, 6:12 pm, Chris Albertson  wrote:

The crystal on the computer motherboard.

At the most basic level, the purpose of NTP is to compute that offset
you see.  That is the offset between the clock on the computer's
motherboard and a perfect clock.The offset value will change with
temperature.  Try watching it for 24 hours or maybe partially block
the computer fan and see what happens in an hour.  NTP keeps
recomputing the offset as your computer's clock changes with
temperature or just with age.

(I think you meant "Satellites  __transmitting__  the GPS signal")

Chris Albertson
Redondo Beach, California




Chris:


  Thanks. I needed that NTP 101 lesson. So is it a stretch to try and
obtain a quality motherboard to improve the frequency offset?




Forget about it!!  Your computer, and just about any other computer, is 
not intended to be a precision clock.  The crystals used in most 
computer clocks flunked the quality control testing for use in a cheap 
wrist watch!


This sad state of affairs is why NTP exists.  It will beat your 
computer's clock into submission!


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Re: [ntp:questions] GPS Jammers in Use by Criminals - Warping Time for Fraud Suggested

[Richard B. Gilbert]

On 2/22/2012 5:16 PM, David Woolley wrote:

An article in the Metro, the free morning paper on the London commuter
transport network, suggests that criminals may be using GPS jamming
equipment to warp the time on financial systems to allow the commission
of fraud.


GPS is not the only source of time!

In the U.S. 60 cycle Alternating Current is the standard and the source
of time.  It's not going to give you the nanoseconds but very few people 
could even explain what a nanosecond is let alone needing nanosecond 
resolution.



Although I can't find the source of that article, the BBC has an
article, presumably from the same underlying source, addressing another
point in that that article, that GPS jammers are increasingly being used
to defeat GPS based car tracking systems.


If anyone wants to track my car's location, you're welcome.  And I hope 
that no one dies of boredom!




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Re: [ntp:questions] GPS Jammers in Use by Criminals - Warping Time for Fraud Suggested

[Richard B. Gilbert]

On 2/22/2012 5:16 PM, David Woolley wrote:

An article in the Metro, the free morning paper on the London commuter
transport network, suggests that criminals may be using GPS jamming
equipment to warp the time on financial systems to allow the commission
of fraud.


GPS is not the only source of time!

In the U.S. 60 cycle Alternating Current is the standard and the source
of time.  It's not going to give you the nanoseconds but very few people 
could even explain what a nanosecond is let alone needing nanosecond 
resolution.



Although I can't find the source of that article, the BBC has an
article, presumably from the same underlying source, addressing another
point in that that article, that GPS jammers are increasingly being used
to defeat GPS based car tracking systems.


If anyone wants to track my car's location, you're welcome.  And I hope 
that no one dies of boredom!




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Re: [ntp:questions] Using a uC based embedded device as SNTP server

[Richard B. Gilbert]

On 2/16/2012 4:52 AM, Thorsten Mühlfelder wrote:

Hello,

I've already posted these questions 8 months ago without answers, but
now the problem came to my mind again. Sorry for double post.

I'm using a Atmel uC embedded device as SNTP server. The code is
working so far, but I wonder what the correct settings are for:
* stratum


If your Atmel uC gets its time from an atomic clock directly, it is 
Stratum 1.  If Atmel uC gets time from a stratum 1 server it is a 
stratum 2 clock and so on.  Each hop adds a little more garbage to the mix.



* precision

Precision describes how finely you can "slice" time.  This has little or
nothing to do with accuracy.


* root dispersion
* reference identifier
* reference timestamp

The embedded device has a battery buffered hardware RTC, that is
capable of 1 second resolution. The used oscillator though has a
frequency tolerance of 20 ppm.
On startup the device tries to get the time from a pre-configured NTP
server once.

In my understanding my server is a stratum 1 with reference identifier
LOCL. Also I chose reference timestamp as last time correction by
SNTP. Is this correct?

I also wonder about the precision an root dispersion settings, as the
RTC only has a resolution of 1 second.

Thanks for any help, I'd like to set it up the right way.


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Re: [ntp:questions] how do I lock in average frequency correction

[Richard B. Gilbert]

On 2/14/2012 10:50 AM, Ron Frazier (NTP) wrote:

On 2/14/2012 9:36 AM, unruh wrote:

On 2012-02-14, Ron Frazier (NTP) wrote:

On 2/13/2012 3:25 PM, Chris Albertson wrote:

On Mon, Feb 13, 2012 at 10:59 AM, Chuck Swiger wrote:

Perhaps a silly question, but, does the "tick" that drives the OS
software clock originate from the RTC or from the CPU master clock at 2
GHz or whatever? Just trying to understand how this stuff works.

Not clear what thei question has to do with frequency stablizing a xtal,
but the system clock is linked to the cpu clock.



I was simply wondering which crystal is the perpetrator. I always
thought the CPU clock was highly accurate.

Ron



Generally, those crystals have failed quality control by the clock/watch 
makers.


They could build a good clock into the computer but that costs money and 
raises prices.  Most people don't care about the computer having

the exact time.

Most people couldn't care less if their wrist watch gains or looses
a second a week.

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Re: [ntp:questions] ntpd wedged again

[Richard B. Gilbert]

On 2/14/2012 1:43 AM, David J Taylor wrote:

"A C"  wrote in message
news:4f398579.9060...@acarver.net...
[]

I'm not sure it's a good idea either but I would really like to
understand why a refclock clamps the polling interval at such a low
value when nearly every bit of documentation says we should be kind to
NTP servers and make sure the polling period is allowed to reach 1024.


If you look back in the archives of this newsgroup you will find that I
asked David Mills a similar question, and he gave an answer. I'm not
sure that I completely understood the answer, though.

I now have lines like the following in my ntp.conf file for my stratum-1
PCs:

server 0.uk.pool.ntp.org minpoll 10
server 1.uk.pool.ntp.org minpoll 10
server 0.nl.pool.ntp.org minpoll 10

As I have three PCs peered fed from different GPS receivers I'm hoping
that the Internet servers are never needed. 

Cheers,
David


The problem with THREE GPS receivers, or just about any other clock, is 
that it it can too easily degenerate to the two server case.  It is well 
known that "a man with two clocks can never be certain what time it is."


Four, five, and seven are the magic numbers for a robust configuration.
Most sites will settle for four.  The very paranoid or the very rich 
might go for seven.



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Re: [ntp:questions] how do I lock in average frequency correction

[Richard B. Gilbert]

On 2/13/2012 2:36 AM, Dave Hart wrote:

On Sun, Feb 12, 2012 at 19:03, Chuck Swiger  wrote:

On Feb 12, 2012, at 9:36 AM, unruh wrote:

The clock crystal ages, and suffers internal crystal "cracks"
migrations, etc, which change the frequency of the crystal. Thus even in
a temperature controlled oven, the crystal frequency will change, but
much of the crystal frequency change is driven by temperature changes.


Agreed, temperature swings will have a major impact on the crystal frequency.


Well, I know what you're saying but we're talking on the order of 1
PPM / degree C.


You might be able to improve the stability of the crystal by ensuring good
airflow and cooling via HVAC as needed.  And I suppose you could adjust the
rate by changing the HVAC set-point, but I don't think the benefit is worth it.

I'd be more likely switch to an OXCO + GPS on a PCI/PCIe card if such as needed.


That's OCXO, oven controlled crystal oscillator.  Why X for crystal?


Crystal is frequently abbreviated as XTAL.  I think this usage may have 
originated in amateur radio.




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Re: [ntp:questions] how do I lock in average frequency correction

[Richard B. Gilbert]

On 2/12/2012 2:03 PM, Chuck Swiger wrote:

On Feb 12, 2012, at 9:36 AM, unruh wrote:

On 2012-02-12, Ron Frazier (NTP)  wrote:

It is my understanding that NTP is continuously making small changes to
the software clock to keep the timing accurate while the os is running.
95% of the time, my computers are doing the same thing and 95% of the
time, I'm doing the same thing with the computers.  Therefore, over a
long time interval, the interrupt usage should be similar, and over a
long time interval, the correct clock frequency to maintain accuracy
should be similar.


That above paragraph is not comprehensible to me. Yes, ntp is making
small changes to the software clock frequency.
What does your doing with the computer have to do with interrupt usage?


I also found it a bit difficult to understand the concern being asked, but:

- some operating systems have or had bugs where they will miss timer interrupts and cause 
the kernel "clock" to run more slowly (ie, a firewall/router running at high 
packets-per-second and seeing a huge # of network interrupts)

- doing some long, max-CPU activity like "transcoding a movie" will heat up the 
system and the crystal


The clock crystal ages, and suffers internal crystal "cracks"
migrations, etc, which change the frequency of the crystal. Thus even in
a temperature controlled oven, the crystal frequency will change, but
much of the crystal frequency change is driven by temperature changes.


Agreed, temperature swings will have a major impact on the crystal frequency.


I also would like to understand how ntp interacts with the Real Time
Clock.  I think I've read that either NTP or the OS (I don't know which)


It depends. ntp itself does not intereact with the real time clock at
all. However, under Linux, if the system clock thinks it is synced, it
resets te real time clock every 11 min to the system clock. also, in the
OS, hwclock is run at the end to reset the real time clock to the system
clock.


Yes, ntpd does not interact with the hardware TOY/RTC at all.  Whether the 
system
itself updates the BIOS/firmware/EFI RTC is both operating system specific and
hardware specific.


will save the time to the RTC when shutting down and retrieve the time
from the RTC when booting up.  I'd like to know if this is true, first
of all, and I'd like to know if it makes any corrections to the clock
rate of the RTC so it is more accurate.


No. it does not, especially with that 11 minute mode, it cannot figure
out the rate of the clock. If you switch off the 11 min mode, by
constantly telling the system clock it is not in sync, then you can use
some versions of hwclock to measure the drift rate of the rtc.
But there is absolutely no way of altering the rate of the rtc without
unsoldering your clock crystal from the motherboard and putting in a new
one, or putting in a trimming capacitor, and adjusting it by hand.


You might be able to improve the stability of the crystal by ensuring good
airflow and cooling via HVAC as needed.  And I suppose you could adjust the
rate by changing the HVAC set-point, but I don't think the benefit is worth it.


Rather than cooling the crystal it's customary to to put the crystal in 
an "oven".  This is not the oven usually used for cooking.  What it does 
is to heat the crystal to a temperature that can be maintained 24x7
and will be a little warmer than the highest temperature that can be 
expected naturally.  A value in the range 120 to 130 degrees F could be 
used.




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Re: [ntp:questions] how to force NTP to use GPS

[Richard B. Gilbert]

On 2/11/2012 4:14 PM, Ron Frazier (NTP) wrote:

Hi all,

I now have my USB GPS working at an acceptable level on both Windows and
Linux using only NTPD. I have the GPS server line set as prefer, but
there are other server lines which poll the internet. Sometimes, the
system selects an internet clock rather than my GPS. How do I force NTP
to use my GPS if it's available, no matter what (within reason). The
only time I ever want it to select an internet server is if the GPS
fails or is not plugged in.

Sincerely,

Ron



ISTR a "prefer" keyword used to instruct NTPD to use a designated
time source if that source is available.  Other sources configured will 
be used only if the "preferred" source is not available or obviously 
insane.  Or something like that!  It goes in NTPD.CONF   IIRC.


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Re: [ntp:questions] Update NTP on FreeBSD 8.2

[Richard B. Gilbert]

On 2/10/2012 11:18 AM, David J Taylor wrote:

"Uwe Klein"  wrote in message
news:36if09-sj3@klein-habertwedt.de...
[]

windows runs on just one platform, badly.


In your view. It actually runs on at least three platforms today, and
likely four tomorrow, and it runs well enough for many users. For NTP
timekeeping can be at the sub-millisecond level, which may or may not
meet your requirements.


The BSDs run on a very wide range of architectures
currently only bested by Linux ( afaik )


FYI: "bested" is not English. "only Linux runs on more".


Sorry!  My dictionary says that you are wrong!

From "The American Heritage Dictionary", Second College Edition"
under the heading for "best" is listed "bested", "To get the better of"; 
"surpass"!


Those dictionaries are handy things to keep around!


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Re: [ntp:questions] what happens if ntp server jumps time BIG TIME

[Richard B. Gilbert]

On 2/9/2012 4:36 PM, bombjack wrote:

Hi,
Scenario:
- I'm in control of a NTP server and can change the time on this
server as I please (this server is "sync'ed to the hw-clock)
- I have a client that is sync'ed with the server above (and only that
server)

What happens if I change the time on the server, lets say 5 years
forward? Will the client sync to the server? and If so, how? big leap?


Yes, BIG LEAP!  But WHAT PROBLEM are you trying to solve??

It will take long time, perhaps as long as eight or ten hours to recover
from this exercise


small steps? Will the flag "-g" affect how the client reacts to this
changes?

Yes, I do realise that this scenario is stupid in many ways. Only one
server, big time changes on the server etc etc, and I do know how to
fix ti, but this is the scenario that I need an answer to.

Any input welcome!

BR,
Fredrik


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Re: [ntp:questions] How do you reply to list postings

[Richard B. Gilbert]

On 2/7/2012 1:38 PM, Ron Frazier (NTP) wrote:

The subject may sound silly, but every time I click reply to one of the
postings on this list, it puts the original message poster's address in
the TO field rather than the public list address. If I want my reply to
go to the list, I have to change the address and either delete the
original person's name or copy to the list. Just wondering if that's
normal.

Sincerely,

Ron



Looks like you need some different and/or better software.  When *I* 
reply to your message it goes to comp.protocols.time.ntp as expected!


Without knowing your hardware and software configuration is, the best
we can do is make some "Scientific Wild Ass Guesses"!

I will not add my own S.W.A.G.

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Re: [ntp:questions] GPS NMEA offset with PPS

[Richard B. Gilbert]

On 12/30/2011 4:02 PM, Tomi Lehto wrote:

Nickolay Orekhov  wrote:

1. If you mark clocks as "true" you somehow fool yourself :-). Because now
if the clocks are real falsetickers you won't even know about it and your
system
will be out of sync and for ex. will show low offset from some falseticker
maybe.


Yes, reading about the "true" option I got the impression that it is "wrong"
way to deal with this. I removed them form the clocks and added tos mindist
with large enough value, now it is set to 0.400 (I don't know if that is
insanely large for the purpose...)



2. NTPD can choose 2 of 3 clock sources but he can't choose 1 of 2 clocks.
So you have to combine NMEA and PPS in one source
or add another ntp server for selection algorithm to work.


With this system the only clock sources will be the local clock and gps, so
no other ntp servers are available. I guess I could try adding 127.0.0.1
as one server?



3. When starting ntpd will at first STEP time to some clock source. I can
suppose It will be NMEA. But later ntpd will choose
PPS because of low jitter and spike detection algorithm can take place. It
will wait for 15 minutes and then make another STEP. To skip this
15 minutes, set time1 to real value.


OK, I watched the system and ntpd seems to pick up PPS either within the
first minute, or after ~15 or 16 minutes from ntpd startup. The NMEA source
is selected pretty quickly and ntpq -p shows small offset for NMEA from
the start (samples are 20 seconds apart):

 remote   refid  st t when poll reach   delay   offset  jitter
==
*GPS_NMEA(0) .GPS.   10 l   10   16  3770.0000.032   2.680
  PPS(0)  .PPS.0 l-   1600.0000.000   0.000
  remote   refid  st t when poll reach   delay   offset  jitter
==
*GPS_NMEA(0) .GPS.   10 l   14   16  3770.0000.029   2.117
  PPS(0)  .PPS.0 l-   1600.0000.000   0.000
  remote   refid  st t when poll reach   delay   offset  jitter
==
*GPS_NMEA(0) .GPS.   10 l2   16  3770.0000.032   1.059
  PPS(0)  .PPS.0 l-   1600.0000.000   0.000
  remote   refid  st t when poll reach   delay   offset  jitter

and after about 15 minutes the PPS is selected.

  remote   refid  st t when poll reach   delay   offset  jitter
==
*GPS_NMEA(0) .GPS.   10 l   14   16  3770.0003.266   3.055
  PPS(0)  .PPS.0 l-   1600.0000.000   0.000
  remote   refid  st t when poll reach   delay   offset  jitter
==
*GPS_NMEA(0) .GPS.   10 l2   16  3770.000   11.005   6.203
oPPS(0)  .PPS.0 l1   1630.000  -340.79   1.406
  remote   refid  st t when poll reach   delay   offset  jitter
==
*GPS_NMEA(0) .GPS.   10 l6   16  3770.0006.842   3.767
oPPS(0)  .PPS.0 l5   1670.000  -343.03   3.024
  remote   refid  st t when poll reach   delay   offset  jitter
==
*GPS_NMEA(0) .GPS.   10 l   10   16  3770.0004.044   4.705
oPPS(0)  .PPS.0 l9   16   170.000  -344.79   4.006
  remote   refid  st t when poll reach   delay   offset  jitter
==
*GPS_NMEA(0) .GPS.   10 l   14   16  3770.000   -0.024   7.511
oPPS(0)  .PPS.0 l   13   16   370.000  -346.15   4.634
  remote   refid  st t when poll reach   delay   offset  jitter


If I understand correctly ntpd adjusts the system clock slowly instead of
quickly setting it to desired time. But how quickly I can expect it to adjust
the system clock if it is within couple of hundred msec from "real" time and
ntpd has got NMEA and PPS available?

NTPD can and will "jump" the clock if the error is greater than some 
small value; I don't recall the exact value.


A properly configured NTPD should not need manual correction unless the
circumstances are really extreme!



That's just a wild guess.
To be more specific, please, could you post your full config first of all,
and then ntpq output
of commands such as "pe", "rv", "cv" and so on short after restart and then
after about half an hour? I think there's some problem in con

Re: [ntp:questions] Accuracy of NTP - Advice Needed

[Richard B. Gilbert]

On 12/25/2011 5:49 AM, Rob wrote:

j...@specsol.spam.sux.com  wrote:

Again, were do you see the word "few" in what I wrote?


That makes the statement so meaningless.  Every distance can be
measured in feet.

Of couse, nobody at Cern would even think of doing that, but that is
another matter.


How many feet in a light year??  ;-)

That should keep you out of trouble for a little while!

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Re: [ntp:questions] Accuracy of NTP - Advice Needed

[Richard B. Gilbert]

On 12/22/2011 11:35 PM, unruh wrote:

On 2011-12-23, Richard B. Gilbert  wrote:

On 12/22/2011 2:11 PM, Paul Sobey wrote:

Dear All,

I work for a firm which requires clocks to be synchronised to quite a
high degree of accuracy.

We have an existing ntp-based infrastructure but want to improve on it
to the point where the bulk of our hosts are synchronised to single
digit microseconds of each other if possible. We have about 400 hosts in
production, spread across about 15 sites.

I hear from many vendors and industry colleagues that 'ntp just isn't
suitable for high precision work and anything less than 1-2ms precision
requires ptp or direct connection to gps clock'. I find these numbers
somewhat suspect, and wanted to ask the advice of you experts. In
particular I've read several threads on this list and other sites which
suggest that highly accurate synchronisations are possible, assuming OS
and network jitter can be minimised.

Our internal testing to this point is that a stock ntpd pointed against
a stratum 1 clock on a low contention gigabit ethernet (stratum 1 source
and client less than 1ms apart) reports its own accuracy at approx 200
microseconds. Further tuning the ntp config by adding the minpoll 4,
maxpoll 6 and burst keywords result in ntpd reported accuracy dropping
to within 10-20 microseconds (as reported by ntpq -p and borne out by
loopstats). Further improvements can be made running ntpd in the RT
priority class.

My questions to you all, if you've read through the above waffle are:

- what is a sensible expected accuracy of ntpd if pointed at several
stratum 1 time sources across a low jitter gigabit network (we'd
probably spread them over several UK and US sites for resiliency but all
paths are low jitter and highly deterministic latency)

- are there any obvious tunables to improve accuracy other than
minpoll/burst and process scheduling class, and how agressive can the
polling cycles be sensible made?

- can ntpd's own reported offset (ntpq -p or loopstats) be trusted
(assuming high priority means it gets scheduled as desired)? I've quoted
our apparent numbers at several people and the response is always 'pfft
you can't trust ntpd to know its own offset' - but nobody can ever tell
me why

I appreciate these may appear to be silly questions with obvious answers
- I am grateful in advance for your patience, and any research sources
you may direct me to.

Many thanks,
Paul


If you can possibly site a GPS antenna and receiver at your location,
you can get microsecond accuracy or better. The receiver will output a
"tick" each second.  One edge of the tick signal will be within about
50 nanoseconds of the "start" of a second.

The receivers cost anywhere from $100 and up.  Some people need, or just
want this level of accuracy.  You do need to be able to site an antenna
with a clear view of the sky.

The last time I heard, there were twenty-seven GPS satellites in
service.  There are usually anywhere from three to five or six above the
horizon at any given time.  Given at least three satellites in
line-of-sight your GPS receiver can figure out the latitude, longitude,
and elevation of your antenna.  Once it has done this it only needs to
see a single GPS satellite to get the time.

This kind of accuracy is far more than most people really need.  It's
there if you need it even if you only need it for "bragging rights"!


Or timing how long it takes neutrinos to get from Cern to Grand Sasso.





How do you "tag" a neutrino so that you can say with assurance that the
the neutrino that left Cern is the same neutrino that arrives at Sasso?


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Re: [ntp:questions] Accuracy of NTP - Advice Needed

[Richard B. Gilbert]

On 12/22/2011 9:17 PM, Chris Adams wrote:

Once upon a time, Richard B. Gilbert  said:

The last time I heard, there were twenty-seven GPS satellites in
service.


There are currently 31 active.


There are usually anywhere from three to five or six above the
horizon at any given time.


It can be up to 8 or 9.


This kind of accuracy is far more than most people really need.  It's
there if you need it even if you only need it for "bragging rights"!


The securities traders (especially HFT) want it.  I suspect the OP is in
that group.  That level of timekeeping has been discussed here before.


I think that the radio astronomers are some of the most demanding.
Joe Average just needs to get to the bus stop or railway station in time
to catch his chosen mode of transportation.

The securities traders generally need to time-stamp their transactions 
within two seconds.


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Re: [ntp:questions] Accuracy of NTP - Advice Needed

[Richard B. Gilbert]

On 12/22/2011 2:11 PM, Paul Sobey wrote:

Dear All,

I work for a firm which requires clocks to be synchronised to quite a
high degree of accuracy.

We have an existing ntp-based infrastructure but want to improve on it
to the point where the bulk of our hosts are synchronised to single
digit microseconds of each other if possible. We have about 400 hosts in
production, spread across about 15 sites.

I hear from many vendors and industry colleagues that 'ntp just isn't
suitable for high precision work and anything less than 1-2ms precision
requires ptp or direct connection to gps clock'. I find these numbers
somewhat suspect, and wanted to ask the advice of you experts. In
particular I've read several threads on this list and other sites which
suggest that highly accurate synchronisations are possible, assuming OS
and network jitter can be minimised.

Our internal testing to this point is that a stock ntpd pointed against
a stratum 1 clock on a low contention gigabit ethernet (stratum 1 source
and client less than 1ms apart) reports its own accuracy at approx 200
microseconds. Further tuning the ntp config by adding the minpoll 4,
maxpoll 6 and burst keywords result in ntpd reported accuracy dropping
to within 10-20 microseconds (as reported by ntpq -p and borne out by
loopstats). Further improvements can be made running ntpd in the RT
priority class.

My questions to you all, if you've read through the above waffle are:

- what is a sensible expected accuracy of ntpd if pointed at several
stratum 1 time sources across a low jitter gigabit network (we'd
probably spread them over several UK and US sites for resiliency but all
paths are low jitter and highly deterministic latency)

- are there any obvious tunables to improve accuracy other than
minpoll/burst and process scheduling class, and how agressive can the
polling cycles be sensible made?

- can ntpd's own reported offset (ntpq -p or loopstats) be trusted
(assuming high priority means it gets scheduled as desired)? I've quoted
our apparent numbers at several people and the response is always 'pfft
you can't trust ntpd to know its own offset' - but nobody can ever tell
me why

I appreciate these may appear to be silly questions with obvious answers
- I am grateful in advance for your patience, and any research sources
you may direct me to.

Many thanks,
Paul


If you can possibly site a GPS antenna and receiver at your location,
you can get microsecond accuracy or better. The receiver will output a
"tick" each second.  One edge of the tick signal will be within about
50 nanoseconds of the "start" of a second.

The receivers cost anywhere from $100 and up.  Some people need, or just 
want this level of accuracy.  You do need to be able to site an antenna 
with a clear view of the sky.


The last time I heard, there were twenty-seven GPS satellites in 
service.  There are usually anywhere from three to five or six above the 
horizon at any given time.  Given at least three satellites in 
line-of-sight your GPS receiver can figure out the latitude, longitude, 
and elevation of your antenna.  Once it has done this it only needs to 
see a single GPS satellite to get the time.


This kind of accuracy is far more than most people really need.  It's 
there if you need it even if you only need it for "bragging rights"!


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Re: [ntp:questions] ntp server pool advice

[Richard B. Gilbert]

On 12/21/2011 3:25 AM, ben slimup wrote:


Dear all,

i m currently working on some project that needs a particular ntp distribution 
design:

i have to site with 4 public ip address, that can be used on both site, i need 
to serve between 10 client to 1 million.. load balanced either on 1 site or 
both.
i have on each site 2  box with 4 ntp server (slot card) that can deliver 
synchronize 10,000client per card
i can also use a L4 load balancer on each site if required, also dns round robin

i would like to know how can i design a proper ntp network with redundancy on 
both site that can handle such client request.

Please expert kindly advise

Thank you

beny


Please use your return key!  Your message overflows a 22" wide screen!!!

You will need a very fast link to your internet provider.  I think T1 
service might be sufficient.  Consult an expert or two!


Be certain that your contract with your Internet Provider (IP) allows 
you to operate a server.  Some providers do not.  Any IP should be able

to handle the load but will almost certainly expect you to pay for the
bandwidth your server will require.


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