[LEAPSECS] operational time -- What's in a name?

[Brian Garrett]

----- Original Message ----- 
From: "Rob Seaman" <seaman at noao.edu>
To: "Leap Second Discussion List" <leapsecs at leapsecond.com>
Sent: Monday, March 31, 2008 10:43 AM
Subject: Re: [LEAPSECS] operational time -- What's in a name?



> Clive D.W. Feather wrote:

>

>> Tony Finch said:

>>> So you think that the millions of existing radio controlled clocks  and 

>>> watches should stop showing civil time?

>>

>> They already do.

>

> Case in point:  When the local Red Cross center relocated a couple of 

> years ago, new RC "atomic" clocks appeared over each blood donor  station.

> [snippage]



> Rather, a clock that claims extreme accuracy (through overtly extreme 

> precision) must ultimately be layered on a well designed system of 

> traceable time signals.  RC time signals are meaningless (no matter  the 

> underlying timescale) if the logistical issues (as described by  Steve, 

> for instance) are ignored.  Logistics keys on developing a  coherent model 

> of the system being operated.

>

> It is not enough to simply create a single perfect clock.  The perfect 

> clock demands a matching distribution protocol.  The ntpwg mailing  list 

> makes interesting reading if one is tempted to believe this is a  solved 

> problem.

>

> What kind of clock does the Red Cross require?  Focus on the use  cases, 

> not the technology.

>

> Rob Seaman

> NOAO

>

It surprises me that the Red Cross needs this kind of accuracy to begin 
with.  The only reason a blood bank would need reasonably accurate clocks is 
that the units collected have to be used within 72 hours according to 
regulations, or so I've read. Surely at least a few minutes leeway is 
allowed, and NIST-traceable accuracy is overkill.  (Commendable overkill, 
sayeth the anal-retentive geek side of me, but overkill nonetheless.)

FWIW, blood banks are usually located in buildings with _lots_ of 
fluorescent lights.  Good luck getting a radio-controlled clock to work in 
an environment like that.


Brian Garrett