Yes, we've been here before. Here are some comments to consider.
There are many forms of "SLS"; from those that spread the leap across one second, or two seconds, or 30 seconds or a minute, or an hour, or a day. Spread it across a year (or however long it's been since the last leap second) and you have UT1. And that's just the versions of SLS that use linear ramping. You can imagine nicer ones that take off and end slowly instead of the abrupt quantum rate change as seen in the utc-sls write-up. 1200 might make a better choice if there are 50/60 Hz effects (1000 is not divisible by 60). Or 300. 1024 or a smaller power of 2 is nicer for low cost, low power devices. 1200 has more common prime factors than 1000 which can come in handy in some cases. You get the idea. Lots of ways to do it. There are SLS where the leap is spread before midnight; those where it's spread after midnight; and those where it is evenly spread on either side of midnight. All these share the same goal of maintaining exactly 86400 inexact seconds per day (something computer clocks are good at). They also all avoid the dreaded 23:59:60 UTC label so there's merit to smoothing as a general concept for almost all timekeeping for human consumption. But as to how it is implemented, or to what rigor, is totally dependent on the needs of the user. Many NMEA outputting GPS receivers have their own way of handling this just fine and it isn't the way sls-utc is defined. No quartz watch or any device using a 32 kHz-based RTC is capable of faithfully implementing utc-sls(1000) because they cannot implement millisecond leaps every second. My point is dictating 1000 seconds as the smoothing interval is a dated and arbitrary choice that's right in one person's mind and for a particular point in computer history -- and a poor engineering "choice" for everyone else; it's either way too long or way too short or way too inconvenient or way too proscriptive. You can smell something is wrong when you see magic moments like "23:43:21" in the spec. Oh wait, I see it's "23:43:19" for negative leap seconds. /tvb www.LeapSecond.com _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
