Thanks to all who replied to my questions about the time on GPS.
The reason I asked about the leap second. Is if the following analog clock GPS
driver included the leap second correction.
Yes it would.
http://www.altronics.com.au/p/k1129-gps-synchronised-clock-kit/
It also corrects it for daylight saving.
Thanks all,
Roderick Wall.
----- Reply message -----
From: "Brooke Clarke" <[email protected]>
To: "sundial list" <[email protected]>
Subject: Time question on GPS TIME and leap second.
Date: Tue, Jan 31, 2017 7:29 AM
Hi Roderick:
GPS time is continuous, that's to say there are no leap seconds or other
changes to it since it started. It uses a 10
bit binary week counter so the week number rolls over after 1024 weeks. This
causes problems for GPS receivers that are
more than a few years old since they have no idea what year it is.
The total number of seconds offset from UTC is transmitted separately so that a
GPS receiver can display either GPS time
or UTC.
Note that the time and position are independent from the year.
http://www.prc68.com/I/Trimpack.shtml#WkRlvr
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
-------- Original Message --------
> Hi all,
>
> Was just listening to the CrowdScience on time. Thanks to whoever posted the
> link to it.
>
> CrowdScience indicated that a leap second was not added for the GPS. They
> also indicated that the GPS gives us UTC time.
>
> Question:
> The UTC time that the GPS gives. Does that have the leap second added?
>
> Thanks,
>
> Regards,
>
> Roderick Wall.
>
> ----- Reply message -----
> From: "Michael Ossipoff" <[email protected]>
> To: "Robert Kellogg" <[email protected]>
> Cc: "sundial list" <[email protected]>
> Subject: Why we should reform the Calendar
> Date: Mon, Jan 30, 2017 8:00 AM
>
> On Sun, Jan 29, 2017 at 2:41 PM, Robert Kellogg <[email protected]>
> wrote:
>
> > Michael goes off looking for the ideal tropical year
>
>
> There isn't an "ideal tropical year", but, as a choice for a
> leapyear-rule's mean-year, the length of the mean tropical year (MTY) is
> best for year-round reduction of longterm calendar-drift. ...and the
> average of the lengths of the March & September Equinox tropical years
> (I'll call that the Average Equinox Year (AEY) ) is a compromise between
> the vernal equinoxes of the North & the South.
>
>
> > , perhaps ignoring effects of the earth's nutations.
> >
>
> Of course. The nutations are small in amplitude & period. They aren't part
> of calendar rules. The mean equinox (nutations averaged-out) is the one
> that is meant when the equinox is spoken of with regard to calendars.
>
>
>
> > I'll still take the one of 1900, most importantly because it defines the
> > SI second.
>
>
> The SI second was defined as 1/86,400 of a mean solar day, for some year in
> the early 19th century. I don't remember exactly what year that was. 1820?
> 1840? 1850?
>
> Evidently it isn't practical to update the length of the SI second, but
> that doesn't mean that calendars have to be based on the ephemeris day, or
> atomic day, consisting of 86,400 SI seconds, when that's known to be
> different from today's mean solar day.
>
> That's why I suggest 365.24217 instead of 365.24219 for the length of the
> mean tropical year (MTYI. It makes sense to base a calendar leap-year
> rule's mean-year on the actual length of a tropical-year (whichever one we
> want to use) on the length of that tropical year in* today's* mean days.
>
>
> >
> >
> > So, contemplating changing the year is non trivial.
>
>
> Evidently there must be some reason why it would be impractical to update
> the length of the SI second. But it isn't necessary to call a MTY 365.24219
> days, when it's really 365.24217 mean days long. ...for the purposes of a
> calendar leapyear rule. There's inevitable inaccuracy due to rounding-off,
> and due to gradual change in the lengths of all the tropical years,
> including the MTY. But that doesn't mean we have to intentionally add
> avoidable error.
>
>
>
> > Contemplating decoupling UTC from the rotation of the earth (ie necessity
> > of being within .9 sec of UT1) likewise has significant consequences.
> > Let's let the IAU chart the future of time.
>
>
> Sure, but it isn't necessary to base a calendar on a day that isn't today's
> mean solar day.
>
> Michael Ossipoff
>
>
>
>
>
> > Dennis and Ken, if you're listening to this discussion, please chime in.
> >
> >
> > On 1/29/2017 12:27 PM, [email protected] wrote:
> >
> >> Send sundial mailing list submissions to
> >> [email protected]
> >>
> >> To subscribe or unsubscribe via the World Wide Web, visit
> >>https://lists.uni-koeln.de/mailman/listinfo/sundial
> >> or, via email, send a message with subject or body 'help' to
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> >>
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> >>
> >> When replying, please edit your Subject line so it is more specific
> >> than "Re: Contents of sundial digest..."
> >>
> >>
> >> Today's Topics:
> >>
> >> 1. Re: Why we should reform the Calendar (Michael Ossipoff)
> >>
> >>
> >> ----------------------------------------------------------------------
> >>
> >> Message: 1
> >> Date: Sun, 29 Jan 2017 12:27:56 -0500
> >> From: Michael Ossipoff <[email protected]>
> >> To: Dan-George Uza <[email protected]>
> >> Cc: sundial list <[email protected]>
> >> Subject: Re: Why we should reform the Calendar
> >> Message-ID:
> >> <CAOKDY5Aes1J6NFKjxXvQ_WxW1x1mfGGq9+F7wFjX72GRaiOLTQ@mail.
> >> gmail.com>
> >> Content-Type: text/plain; charset="utf-8"
> >>
> >>
> >> Here are two (unimportant) objections to the Nearest-Monday year-start
> >> system:
> >>
> >> 1. It's based on the Gregorian leapyear-rule, meaning that it isn't
> >> self-contained & free-standing. Mostly an aesthetic objection, and I don't
> >> consider it important.
> >>
> >> 2. It inherits certain properties of the Gregorian Calendar, which could
> >> otherwise be adjustable, choose-able. This, too, I consider only an
> >> aesthetic objection.
> >>
> >> Here are the properties that I refer to:
> >>
> >> The Gregorian leapyear-rule was designed to minimize the date's variation
> >> at the (northern) Vernal Equinox, the March equinox.
> >>
> >> We often hear it said that the mean tropical year is the time from one
> >> March equinox to the next. Not so. That's because the length of a tropical
> >> year depends on at what point of the ecliptic it's measured.
> >>
> >> A tropical year is a seasonal year, the time during which the center of
> >> the
> >> sun leaves & returns to some particular point of the ecliptic. That
> >> duration is different, depending on the point of the ecliptic at which
> >> it's
> >> measured.
> >>
> >> That's because the Earth's orbit is continuously changing, due to
> >> perturbation by other planets, mostly Jupiter.
> >>
> >> So, for example, the following tropical years have different durations:
> >> The
> >> March Equinox year, the September Equinox year, the June Solstice year,
> >> and
> >> the December Solstice year.
> >>
> >> Leapyear-rules try to achieve some desired "mean year". The Gregorian
> >> leapyear-rule's mean-year is 365.2425 days. Probably mean solar days, I
> >> assume. As I said, the Gregorian's mean-year is intended to approximate
> >> the
> >> March Equinox year.
> >>
> >> A mean solar day is the duration between meridian-transits of the mean
> >> sun.
> >>
> >> The mean sun is a fictitious sun that goes around the celestial equator at
> >> a constant rate, coinciding at the equinoxes with another fictitious sun
> >> that goes around the ecliptic at a constant rate and coincides with the
> >> real sun at aphelion & perihelion.
> >>
> >> Often the length of (various kinds of) a tropical year is given in
> >> ephemeris days (defined in terms of planetary motions), also callled
> >> atomic
> >> days.(when defined in terms of atomic clock measurements). The length of
> >> an
> >> ephemeris day was fixed in the early 19th century. But, since then, the
> >> length of the day has increased a bit, and so the ephemeris day no longer
> >> matches the mean solar day.
> >>
> >> For example, we often hear it said that a mean tropical year is 365.24219
> >> days. But that's ephemeris days. According to a Wikipedia article
> >> (calendarists that I've spoken with haven't expressed disagreement with
> >> it), a mean tropical year is actually currently about 365.24217 mean solar
> >> days.
> >>
> >> The length of the mean tropical year is the (current value of the)
> >> arithmetic mean of the lengths of the tropical year measured at all the
> >> points of the ecliptic.
> >>
> >> So, if you calculated two Earth orbits, accounting for planetary
> >> perturbations. recording the time at many different points of the
> >> ecliptic,
> >> and then used those times to calculate the tropical year with respect to
> >> those many points of the ecliptic, and then, over one circuit around the
> >> ecliptic, numerically integrated the tropical-year-length, with respect to
> >> ecliptic longitude, and then divided by 2 pi radians ( = 360 degrees),
> >> that
> >> would give you the length of a mean tropical year.
> >>
> >> As I said, according to Wikipedia, it's currently about 364.24217 days.
> >>
> >> So, anyway, the Gregorian leapyear rule's mean-year, of 365.2425 days is
> >> intended as an approximation of the March equinox year of about (it seems
> >> to me) 365.24239 days.
> >>
> >> It's understandable that they chose to favor the Vernal Equinox year. The
> >> equinoxes are the time when the solar declination is changing fastest, and
> >> when the season is changing fastest.
> >>
> >> Problem: The Northern Hemisphere's Vernal Equinox isn't the Southern
> >> Hemisphere's Vernal Equinox. The Vernal Equinox, near the beginning of
> >> Spring, is a revered, honored & celebrated time. But why should the people
> >> of the Southern Hemisphere celebrate the *northern* Vernal Equinox?
> >>
> >>
> >> In 1582 that wasn't a problem for Europeans. But this is a different
> >> century now. In this century, choosing the northern Vernal Equinox as the
> >> basis for the calendar's mean year is more than a little
> >> north-chauvinistic
> >> and inegalitarian.
> >>
> >> So I'd prefer to use an approximation to the mean tropical year, instead
> >> of
> >> the March equinox year, as a leapyear-rule's mean year. That's what my
> >> leapyear-rule proposal does. (I'll get to that soon).
> >>
> >> Another fair choice, another good compromise between North & South, would
> >> be a mean-year length that's the arithmetic average of the March &
> >> September Equinox years.
> >>
> >> Some calendarists like the June Solstice tropical year, as a mean-year for
> >> a leapyear-rule.
> >>
> >> That's because the we're now only about a millennium into a roughly 10,000
> >> year period during which the length of the June Solstice year will change
> >> remarkably little--not enough to cause any significant
> >> calendar-displacement with respect to the seasons..
> >>
> >> To quote one calendarist: "Welcome to the 1st millennium of the Age of the
> >> June Solstice Year!"
> >>
> >> So the current period of remarkable stability of the length of the June
> >> Solstice year has only been in effect since roughly the time of the Battle
> >> of Hastings.
> >>
> >> So of course the June Solstice tropical year has great appeal as the
> >> mean-year for a leapyear-rule. And that wouldn't be unfair to the South,
> >> because the Winter Solstice is celebrated as much as the Summer Solstice.
> >>
> >> Though my calendar-proposal is to use the mean tropical year, or the
> >> arithmetic average of the March & September Equinox years as the mean year
> >> for a leapyear-rule, I'd have no objection at all to the use of the June
> >> Solstice year, which has great appeal.
> >>
> >> The point is that we can choose what tropical year we use for a mean year
> >> for a calendar's leapyear-rule. But if we use the Nearest-Monday
> >> year-start
> >> rule, we're inheriting the Gregorian's use of the March Equinox year as
> >> the
> >> tropical year that the calendar's mean year approximates.
> >>
> >> That isn't really a problem, but it would be nice to make that choice for
> >> ourselves--as my Minimum-Displacement leapyear-rule (defined later) does.
> >>
> >> The other things is that the Gregorian's 365.2425 day mean-year, being
> >> more
> >> approximate, results in more drift (with respect to its intended tropical
> >> year length) than would a more precise approximation. And when the
> >> calendar's relation between date & ecliptic longitude oscillates, in the
> >> leapyear-system, about what central date/season relation does it
> >> oscillate? Wilth the Gregorian, and hence with Nearest-Monday, that's out
> >> of our hands, decided for us.
> >>
> >> I'm not saying that that's a problem either.
> >>
> >> It's just that it would be *nice* to have the luxury of choosing, for
> >> ourselves, 1) what tropical year we want the calendar's mean-year to
> >> approximate; and 2) what date/season relation we want for the calendar's
> >> center of oscillation.
> >>
> >> The Minimum-Displacement leapyear-rule allows the luxury of making our own
> >> choice of those two adjustment-parameters.
> >>
> >> This posting is already very long, and so I'll save the
> >> Minimum-Displacement leapyear-rule for a (immediately subsequent) next
> >> posting.
> >>
> >> Michael Ossipoff
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> I seems to me that the March Equinox tropical year is something like
> >> 365.24239
> >>
> >>
> >>
> >> On Sat, Jan 28, 2017 at 8:54 PM, Michael Ossipoff <[email protected]
> >> >
> >> wrote:
> >>
> >> I don't think it's really off-topic, because, with sundials, we're
> >>> interested in the EqT, which is given in terms of the calendar's dates.
> >>>
> >>> Though Gorman is a comedian, he's obviously given the matter some serious
> >>> consideration, and I perceive some serious interest in calendar-reform.
> >>>
> >>> But I have a few disagreements with his proposal:
> >>>
> >>>
> >>>
> >>> *1. Blank Days:*
> >>> Gorman proposes a "fixed calendar", a calendar that will be the same for
> >>> every year. I have no objection to that. After all, so far as we know
> >>> (except for each year setting a new record for increasing global warming)
> >>> what we can expect from each year, nature-wise, is really the same. So,
> >>> why
> >>> should two successive years have different calendars, with different
> >>> dates
> >>> having different days-of-the-week?
> >>>
> >>> So far so good. There are two ways proposed for achieving a fixed
> >>> calendar:
> >>>
> >>> *1. Blank Days:*
> >>>
> >>> A fixed calendar must have a number of days that's a multiple of 7,
> >>> That's
> >>> what enables each calendar to start on the same day of the week, allowing
> >>> every date to have a day-of-the-week that doesn't change from year to
> >>> year.
> >>> So Gorman would make one of the 365 days a "blank day", a day that isn't
> >>> a
> >>> day of the week. Then the days-of-thes-week would resume after that day.
> >>> so
> >>> the year would have only 364 days that are days of the week. That being a
> >>> multiple of 7, each year will start on the same day of the week, as
> >>> desired.
> >>>
> >>> Problem: I'm sorry, but it doesn't make any sense for the day after a
> >>> Saturday to be anything other than a Sunday. ...or for there to be an
> >>> intervening day between a Saturday & a Sunday.
> >>>
> >>> Speaking for myself, I completely reject "blank-days". And I'm not the
> >>> only one. Elizabeth Achellis, over several decades, up to around 1955,
> >>> proposed a fixed calendar with blank-days. The League of Nations, and
> >>> later
> >>> the U.N. were giving serious consideration to it, and it might have been
> >>> accepted, except for the strong opposition to the blank-days,
> >>>
> >>> A compromise was offered to Achellis: A leap-week (described in the next
> >>> section below), to achieve a fixed calendar. She wouldn't accept that
> >>> compromise, and her proposal was indefinitely tabled around 1955, and
> >>> never
> >>> got anywhere since. You could say that the blank-days were the Achilles'
> >>> heel of Achellis' calendar proposal.
> >>>
> >>>
> >>>
> >>> *Leap-Week:*
> >>> So a 364 day common (non-leap) year achieves a fixed calendar, because
> >>> 364
> >>> is divisible by 7. What about the 365th day? Well, we could deal with it
> >>> the same way we deal with the fact that the 365 day year is shorter than
> >>> the 365.24217 day Mean Tropical Year (MTY)...by occasionally lengthening
> >>> a
> >>> year, to periodically compensate for the length-mismatch. So we'd deal
> >>> with
> >>> the short common year just as we do now.
> >>>
> >>> So, what we do is have a 364-day common year, and (by using a leap-year
> >>> rule that I'll talk about later), when that 364-day common year gets
> >>> about
> >>> half a week out-of-step with the seasons, we add a leapweek, to set that
> >>> displacement back.
> >>>
> >>> Gorman didn't talk about the leapyear-system, and we can presume that he
> >>> meant to use the existing Gregorian leapyear system, which would be fine,
> >>> for a leapday calendar such as he proposes. But for a leapweek calendar,
> >>> which is what I (and many others) propose, a new leapyear system is
> >>> required. No problem. I'll get to that after I discuss my disagreements
> >>> with Gorman's proposal.
> >>>
> >>> Summary: A fixed calendar should be achieved via a leapweek, instead of
> >>> by
> >>> blank-days. If Achellis had agreed to that, we might be using her
> >>> calendar
> >>> right now.
> >>>
> >>> *2. Thirteen Months:*
> >>>
> >>> Really, the only reason for a reform calendar to have months, is for
> >>> continuity & familiarity with our current Roman-Gregorian Calendar.
> >>>
> >>> For example, Elizabeth Achellis's *World Calendar *had, in each quarter,
> >>>
> >>> months with the following lengths: 31,30,30. Having 12 months, with 30
> >>> or
> >>> 30 or 31 days, means that the calendar is familiar, looks familiar, and
> >>> it
> >>> means that the dates in the new calendar have really the same seasonal
> >>> meaning as the dates in the old calendar.
> >>>
> >>> Achellis' 31,30,30 quarters achieves that. But there are other proposals
> >>> of a calendar with
> >>> 30,30,31 quarters. The advantage?:
> >>>
> >>> 1. The 30,30,31 calendar's months' start-days never differ by more than a
> >>> day, from those of our current Roman months, when both month-systems
> >>> start
> >>> on the same day. Achellis' 31,30,30 quarter system can differ by at least
> >>> twice as much.
> >>>
> >>> 2. The 30,30,31 quarters divide the weekdays most equally between the
> >>> months of the quarter.
> >>>
> >>> So, if you're going to have months at all (and that's for continuity &
> >>> familiarity), then you want 12 months, of 30 & 31 days. Preferably the
> >>> 30,30,31 quarters.
> >>>
> >>> With 13 months of 28 days, the dates wouldn't have anything like the
> >>> seasonal meaning that they do now. Continuity, familiarity, and the
> >>> justification for having months at all, would be lost.
> >>>
> >>> The 30,30,31 quarter system is an improvement over our current Roman
> >>> months, because the months are much more uniform. That allows much
> >>> meaningful & accurate monthly statistics.
> >>>
> >>> But suppose you want something more radical (as is Gorman's 28X13
> >>> system):
> >>>
> >>> In that case, just don't have months, because their continuity &
> >>> familiarity purpose would be lost anyway. Use the WeekDate system.
> >>>
> >>> No months.
> >>>
> >>> Weeks are numbered.
> >>>
> >>> Here's today's date in the (currently internationally widely-used) ISO
> >>> WeekDate calendar:
> >>>
> >>> 4 Saturday
> >>>
> >>> That means Saturday of the 4th week.
> >>>
> >>> Actually, because not all countries and languages call the da
> >>>
> >>> ys of the week by the same names, here is how the ISO (International
> >>> Standards Organization) words today's date.
> >>>
> >>> 2017W046
> >>>
> >>> The "W" indicates that the WeekDate system is being used.
> >>>
> >>> The "04" denotes the 4th week.
> >>>
> >>> The "6" denotes the 6th day of that week.
> >>>
> >>> (The ISO WeekDate Calendar uses a week (and therefore a year) that begins
> >>> on a Monday, probably so that the weekend won't be split in half.)
> >>>
> >>> The ISO WeekDate Calendar is, as I said, widely used internationally, by
> >>> Companies & Governments, for their planning of business & governmental
> >>> dates & events. ...making it easy to plan them in advance once, and then
> >>> leave them, because it's a fixed calendar. Of course the resulting dates
> >>> then have to be eventually translated into Roman-Gregorian dates.
> >>>
> >>>
> >>> ...but they wouldn't have to, if we adopted the ISO WeekDate calendar as
> >>> our civil calendar, worldwide.
> >>>
> >>> ISO WeekDate has the great advantage of use-precedent. ...lots of it.
> >>>
> >>> I personally like the ISO WeekDate as the best calendar-reform proposal.
> >>>
> >>> But, recognizing that many people wouldn't want to give up the months,
> >>> and
> >>> would want to keep them for familiarity & continuity, the 30,30,31
> >>> month-system could be a good alternative proposal, if ISO WeekDate isn't
> >>> accepted.
> >>>
> >>> But it has been argued that ISO WeekDate is so convenient, and already so
> >>> widely-used, that it could easily edge-out the Roman-Gregorian Calendar,
> >>> from the bottom up, by increasingly wide use, if companies & government
> >>> start using it so much that the public start finding it convenient to use
> >>> it too.
> >>>
> >>> So those are my two disagreements with Gorman's proposal, and my
> >>> alternative suggestions.
> >>>
> >>> But I should comment on the leapyear rule. Actually, the ISO WeekDate
> >>> Calendar deals with that in a really easy, natural, simple & obvious way.
> >>>
> >>> Each ISO WeekDate year starts on whatever Monday is closest to the
> >>> Gregorian January 1st of that year. So, for example, this year, 2017, the
> >>> Gregorian year started on a Sunday. So the nearest Monday to Gregorian
> >>> January 1st was January 2nd. That Monday, Gregorian January 2nd, is the
> >>> day
> >>> on which ISO WeekDate 2017 started.
> >>>
> >>> As I said, today, in the ISO WeekDate Calendar, is:
> >>>
> >>> 4 Saturday
> >>>
> >>> (or 2017W046)
> >>>
> >>> That way of defining the start of the ISO WeekDate year (the Monday
> >>> closes
> >>> to Gregorian January 1st) is called the Nearest-Monday year-start system.
> >>>
> >>> Note that the Nearest-Monday year-start system doen't have to mention
> >>> leapyears or leapweeks at all. It's *effectively* a leapweek calendar,
> >>> because some of the years have 53 weeks instead of 52. But the simple
> >>> Nearest-Monday year-start rule doesn't need to mention leapyears or
> >>> leapweeks.
> >>>
> >>> Not only is it used with the ISO WeekDate Calendar, but of course it
> >>> could
> >>> also be used with a 30,30,31 quarters calendar too.
> >>>
> >>> Calendar reform advocates propose all manner of different leapyear
> >>> systems. But there's nothing wrong with the Nearest-Monday year-start
> >>> system, and conversations have suggested to me that Nearest-Monday would
> >>> be
> >>> the favorite way to make a fixed calendar.
> >>>
> >>> In fact, with Nearest-Monday, the maximum displacement of dates with
> >>> respect to seasons, is barely more than the ideal minimum that could be
> >>> achieved by the fanciest leapyear system.
> >>>
> >>> I also propose a fancier, deluxely-adjustable system, but I won't try
> >>> your
> >>> patience with that here, because Nearest-Monday is entirely good enough,
> >>> and is the system with obviously by far the best acceptance-potential.
> >>>
> >>> Michael Ossipoff.
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> On Sat, Jan 28, 2017 at 3:38 PM, Dan-George Uza <[email protected]
> >>> >
> >>> wrote:
> >>>
> >>> A bit off topic, but I enjoyed this quite a lot!
> >>>>
> >>>>https://youtu.be/EcMTHr3TqA0
> >>>>
> >>>> Dan
> >>>>
> >>>> ---------------------------------------------------
> >>>>https://lists.uni-koeln.de/mailman/listinfo/sundial
> >>>>
> >>>>
> >>>>
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> >> Subject: Digest Footer
> >>
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> >> ------------------------------
> >>
> >> End of sundial Digest, Vol 133, Issue 27
> >> ****************************************
> >>
> >>
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