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Discussion of precise time and frequency measurement

possible negative leap second

Rsec Van der leij

Sat, Mar 30, 2024 11:46 AM

On 30 Mar 2024, at 12:18, Steve Allen via time-nuts time-nuts@lists.febo.com wrote:

UTC with leap seconds is the time scale that was "good enough for
international government work" until it became expedient to rewrite
national laws about time. That was the goal in 1970.

And that is exactly what we got. A worldwide consistent time for us humans, and the machines use whatever is most convenient.

I'm typing this on an iPad, that has GNSS built in. The clocks determining my exact location run UT1 when they use (US) GPS, run GTS (which is directly derived from TAI) when using Galileo and STFR (which is referenced to UTC+3, and uses leap seconds) when using GLONASS. And so on.

However: I get my local time. CET. (CEST will be tomorrow.) Less than a second difference from TAI + 37 leapseconds. 50 µs if I read the graph correctly.

A man with one clock knows the time. A man with two clocks is never sure of the right time.

regards,

Ruben

> On 30 Mar 2024, at 12:18, Steve Allen via time-nuts <time-nuts@lists.febo.com> wrote: > > UTC with leap seconds is the time scale that was "good enough for > international government work" until it became expedient to rewrite > national laws about time. That was the goal in 1970. And that is exactly what we got. A worldwide consistent time for us humans, and the machines use whatever is most convenient. I'm typing this on an iPad, that has GNSS built in. The clocks determining my exact location run UT1 when they use (US) GPS, run GTS (which is directly derived from TAI) when using Galileo and STFR (which is referenced to UTC+3, and uses leap seconds) when using GLONASS. And so on. However: I get my local time. CET. (CEST will be tomorrow.) Less than a second difference from TAI + 37 leapseconds. 50 µs if I read the graph correctly. A man with one clock knows the time. A man with two clocks is never sure of the right time. regards, -- Ruben

ericsp@gmail.com

Tue, Apr 16, 2024 4:33 AM

I can confirm that the BG7TBL is sill running a touch slow. Mine was a 2019 unit that was delivered a few weeks ago. At least from what the ebay listing said.

With 20,000 samples and a gate time a 1 Second

Mean was 9.999 999 998 547 91

So the software bug might still be present
Frequancy Counter was a Keysight 53230A

-----Original Message-----
From: David Bridgham via time-nuts time-nuts@lists.febo.com
Sent: Thursday, March 28, 2024 4:12 PM
To: Discussion of precise time and frequency measurement time-nuts@lists.febo.com
Cc: David Bridgham dab@froghouse.org
Subject: [time-nuts] Re: question about GPS time

On Thu, Mar 28, 2024 at 3:56 PM Jim Harman via time-nuts < time-nuts@lists.febo.com> wrote:

The u-blox receivers have UBX messages that provide the current GPS
and UTC time as well as information about the number of leap seconds
that have occurred and the time, date, and direction of any upcoming leap second.

Indeed, thanks. That's just what I was looking for. In fact, I see from the documentation of one u-blox receiver I checked that they are quite explicit about just how they handle leap seconds in their UTC reporting (that's a good sign) as well as offering the option of choosing which time base of all the different GNSS options they implemented.

Thanks,
Dave

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I can confirm that the BG7TBL is sill running a touch slow. Mine was a 2019 unit that was delivered a few weeks ago. At least from what the ebay listing said. With 20,000 samples and a gate time a 1 Second Mean was 9.999 999 998 547 91 So the software bug might still be present Frequancy Counter was a Keysight 53230A -----Original Message----- From: David Bridgham via time-nuts <time-nuts@lists.febo.com> Sent: Thursday, March 28, 2024 4:12 PM To: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com> Cc: David Bridgham <dab@froghouse.org> Subject: [time-nuts] Re: question about GPS time On Thu, Mar 28, 2024 at 3:56 PM Jim Harman via time-nuts < time-nuts@lists.febo.com> wrote: > The u-blox receivers have UBX messages that provide the current GPS > and UTC time as well as information about the number of leap seconds > that have occurred and the time, date, and direction of any upcoming leap second. > Indeed, thanks. That's just what I was looking for. In fact, I see from the documentation of one u-blox receiver I checked that they are quite explicit about just how they handle leap seconds in their UTC reporting (that's a good sign) as well as offering the option of choosing which time base of all the different GNSS options they implemented. Thanks, Dave _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com