[LEAPSECS] Crunching Bulletin B numbers (POSIX time)

Warner Losh imp at bsdimp.com
Wed Feb 23 13:23:37 EST 2011

On 02/23/2011 05:57, Richard B. Langley wrote:

> For those who might not be aware. Loran-C in North America is dead. It

> might be resurrected as eLoran or some other LF service in the future:

> http://www.ursanav.com/sites/default/themes/danland/images/buzz/pdfs/LF-Solutions-for-APNT-ION2011.pdf


Well, eLoran was implemented in the North American chain a couple of
years before they started to shut it off. Given that the stations have
been decommissioned and the towers blown up in at least some places, I
doubt it will ever resurrect.

But the requirements of that system, and how they interacted with other
requirements when coupled with inflexible military bureaucracy shows
that there's a wide diversity of requirements for some problem domains
that you don't run into with a server in a computing center.



> -- Richard


> Quoting Ian Batten <igb at batten.eu.org>:



>>> Nope. tried that when getting the spec approved. Approximate times

>>> weren't allowed. UTC times were required. There was no way to

>>> indicate approximate time in the user interfaces present (how do you

>>> blink a 5071A anyway :). The other systems that interfaced to ours

>>> had a fixed format, and required UTC and not approximate UTC for a

>>> while and then a possible jump in time to actual UTC.


>> Well, if the use-case is navigation (Loran, military) then UTC sans

>> leap seconds isn't much use to you anyway, so the "solution" of

>> dropping them would take your requirement with it, and you'd seen

>> something closer to UT1. And of course, requirements are simply line

>> items on an invoice, and if deriving immediate UTC costs 10X rather

>> than X, the customer has to make a decision on whether they're

>> prepared to pay for it. Just saying "my customer demands X and

>> therefore the rest of you need to enable X" isn't realistic.


>> ian


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> | Richard B. Langley E-mail:

> lang at unb.ca |

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