[LEAPSECS] Crunching Bulletin B numbers (POSIX time)

[Warner Losh]

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: 

> lang at unb.ca         |

> | Geodetic Research Laboratory                  Web: 

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