Re: [LEAPSECS] Internet-Draft on UTC-SLS

From: Poul-Henning Kamp <phk_at_PHK.FREEBSD.DK>
Date: Thu, 19 Jan 2006 19:04:47 +0100

In message <>, Rob Seaman writes:

>> if you look at *any* form of PLL (circuit or software), then you
>> will find that its very purpose is to implement "rubber seconds",
>> that is to implement phase adjustments via low-pass filtered
>> temporary changes in frequency.
>An excellent observation.

But missing the point entirely: We use PLL because we want to
steer things to be synchronous, not because we see them as a
means to implement rubber seconds.

>> 1000 seconds is an incredible silly chosen number in an operational
>> context. At the very least make it 15, 30 or 60 minutes.
>I would tend to agree with this. The Babylonians must have their
>kilogram of flesh. How about 10 minutes - 5 before midnight and 5

That's far to big a torque: 16666.6666 PPM

>> Advantages:
>> Sufficient resolution to represent any likely physical
>> measurement or realizable frequency for the forseeable
>> future (13.8e-18 seconds resolution).
>Any guess at "likely physical measurements" is going to fall short
>for some purposes. For one thing, one might want to represent
>theoretical values in addition to experimental. That said, you are
>likely correct for "our purposes".

Heisenberg, Bohr and Planck has a lesson for you :-)

>> Now, please show some backbone and help solve the problem rather
>> than add to the general kludgyness of computers.
>Do you find this "tone of voice" productive when collaborating? :-)

You know, I've been in computing for so long that I have become
alergic to kludges and "quick fixes" of all kinds. The worse
and the more hackish they are, the more red spots I get.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk_at_FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Received on Thu Jan 19 2006 - 10:15:28 PST

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