[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.
Warner
>
> -- 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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>
>
>
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>
> | Richard B. Langley E-mail:
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> | Geodetic Research Laboratory Web:
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