The tabulations of the times of emission of radio broadcasts of UTC
were given in units of, and with an accuracy of 0.0001 s; i.e., 100
microseconds.
The tabulations of the intercomparisons between the time scales in
those laboratories are given with decimals to 0.1 microsecond, or 100
On Tue 2015-05-05T15:32:30 -0700, Paul Hirose hath writ:
The rubber time era can be tricky. I just finished a major rewrite
of my UTC implementation in the C# language. The goal was improved
accuracy before 1972. Although the old version passed all my tests
at 1 microsecond accuracy, it began
On 2015-03-06 18:02, Harlan Stenn wrote:
When we get a bit more down the road with NTF's General Timestamp API,
I'd appreciate your taking a look at what we're doing and helping out in
any way you are up for. One of the issues that will need more attention
is pre-1972 stuff.
The rubber time
How fare back before 1972 do you want to go?
Before leap seconds, before TT, TDT, TAI. Entangled in the roots of
ET and Delta-T...
Back in the 70s and 80s there was considerable effort at JPL to improve
the models of orbital motion of the Galilean satelltes of Jupiter. The
existing theory,
I didn't think that NTP or POSIX or PTP is what we'd call a
timescale. NTP is a UTC synchronization algorithm.
If we give the subword scale its usual meaning, then NTP is a
(also) a timescale: It carefully defines the scale on which it is
going to synchronize computer clocks, in
Hi Tom,
On 2015-03-12 09:50 PM, Tom Van Baak wrote:
Brooks wrote:
Many timekeeping systems seem to be designed for only indicating now
counting forward, including NTP, POSIX, and PTP, taking short-cuts to
avoid supplying full Leap Second and local-time metadata.
Warner wrote:
A clock doesn’t
On Fri 2015-03-13T07:29:40 +, Poul-Henning Kamp hath writ:
But more importantly, when we get to the point were we are arguing
over the meaning of common well known words we might as well stop it.
That's kindof funny because two weeks from now in Geneva at the
CPM15-2 meeting for Agenda Item
On Thu, 12 Mar 2015 18:50:56 -0700, Tom Van Baak wrote:
I didn't think that NTP or POSIX or PTP is what we'd call a timescale.
As discussed in other responses, a timescale requires only three
things, a definition of zero time (or a specified time), a definition
of the second (or some other
Hi Tom,
On 2015-03-12 02:57 AM, Tom Van Baak wrote:
Brooks,
A couple more comments on your questions.
Many timekeeping systems seem to be designed for only indicating now
counting forward, including NTP, POSIX, and PTP, taking short-cuts to
avoid supplying full Leap Second and local-time
On Mar 12, 2015, at 3:57 PM, Tom Van Baak t...@leapsecond.com wrote:
Brooks,
A couple more comments on your questions.
Many timekeeping systems seem to be designed for only indicating now
counting forward, including NTP, POSIX, and PTP, taking short-cuts to
avoid supplying full Leap
Brooks wrote:
Many timekeeping systems seem to be designed for only indicating now
counting forward, including NTP, POSIX, and PTP, taking short-cuts to
avoid supplying full Leap Second and local-time metadata.
Warner wrote:
A clock doesn’t need to know its past. But a time scale is more than
Brooks Harris bro...@edlmax.com wrote:
On 2015-03-07 03:01 PM, Steve Allen wrote:
I would say that the intent NTP and POSIX is to correspond to civil
time in contemporary use. Therefore, for dates before 1972-01-01
NTP and POSIX are counting seconds of UT.
This paragraph in your email
On 2015-03-09 08:40 AM, Tony Finch wrote:
Brooks Harris bro...@edlmax.com wrote:
On 2015-03-07 03:01 PM, Steve Allen wrote:
I would say that the intent NTP and POSIX is to correspond to civil
time in contemporary use. Therefore, for dates before 1972-01-01
NTP and POSIX are counting seconds
leap59 and leap61 are Leap Second announce signals, set 12 hours prior
to the insert. There has been discussion about when the official
announcements and expiration should be announced. ITU Rec 460 says
...at least eight weeks in advance. PTP can't do that, a point to keep
in mind.
On 2015-03-09 02:10 PM, Tom Van Baak wrote:
leap59 and leap61 are Leap Second announce signals, set 12 hours prior
to the insert. There has been discussion about when the official
announcements and expiration should be announced. ITU Rec 460 says
...at least eight weeks in advance. PTP can't do
On Mar 7, 2015, at 4:50 PM, Joseph Gwinn joegw...@comcast.net wrote:
On Sat, 07 Mar 2015 14:14:07 -0500, Brooks Harris wrote:
Hi Gerard,
On 2015-03-07 12:04 PM, G Ashton wrote:
Brooks Harris wrote on Saturday, March 7, 2015 11:50 :
.
.
The challenge I'm trying to solve is to provide
On Sun, 08 Mar 2015 12:24:42 -0400, Brooks Harris wrote:
On 2015-03-07 06:50 PM, Joseph Gwinn wrote:
On Sat, 07 Mar 2015 14:14:07 -0500, Brooks Harris wrote:
In the discussions I've been involved with many people argued
strenuously we don't care about the past, only accurate date-time
going
On Mar 8, 2015, at 10:24 AM, Brooks Harris bro...@edlmax.com wrote:
I think the only way the industry can eventually converge on reliable civil
time representation is to refine the underlying time mechanisms in POSIX in
some manner that allows a migration to a more comprehensive UTC
On 2015-03-08 05:00 PM, Warner Losh wrote:
On Mar 8, 2015, at 10:24 AM, Brooks Harris bro...@edlmax.com wrote:
I think the only way the industry can eventually converge on reliable civil time representation
is to refine the underlying time mechanisms in POSIX in some manner that allows a
Hi Steve,
On 2015-03-07 03:01 PM, Steve Allen wrote:
On Sat 2015-03-07T14:14:07 -0500, Brooks Harris hath writ:
It is typically warned that date and time before 1972 cannot be
accurately represented with NTP or POSIX, for examples.
I would say that for PTP
* all seconds are always SI seconds
On 2015-03-07 06:50 PM, Joseph Gwinn wrote:
On Sat, 07 Mar 2015 14:14:07 -0500, Brooks Harris wrote:
In the discussions I've been involved with many people argued
strenuously we don't care about the past, only accurate date-time
going forward!. The reason I'm choosing to ignore the subject of
Brooks Harris wrote:
It seems to me NTP and POSIX as well as other timescales concerned
with civil time, are essentially disconnected from reality,
expressing idealized measurement scales.
That's very much what they're not. TT is idealised, and TAI less so.
Hi Gerard,
On 2015-03-07 12:04 PM, G Ashton wrote:
Brooks Harris wrote on Saturday, March 7, 2015 11:50 :
.
.
The challenge I'm trying to solve is to provide a deterministic timekeeping
and labeling scheme for date and time *after* 1972-01-01T00:00:00Z (UTC) =
1972-01-01T00:00:10 (TAI). This
Brooks Harris wrote on Saturday, March 7, 2015 11:50 :
.
.
The challenge I'm trying to solve is to provide a deterministic timekeeping
and labeling scheme for date and time *after* 1972-01-01T00:00:00Z (UTC) =
1972-01-01T00:00:10 (TAI). This is essentially the purpose of civil time
timekeeping
On Sat 2015-03-07T14:14:07 -0500, Brooks Harris hath writ:
It is typically warned that date and time before 1972 cannot be
accurately represented with NTP or POSIX, for examples.
I would say that for PTP
* all seconds are always SI seconds
* seconds after 1972-01-01 correspond to (TAI - 10)
*
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