RE: [LEAPSECS] consumer-quality clocks

From: <>
Date: Sat, 30 Sep 2000 17:09:33 -0400

I believe the cheapest clocks that can keep 1 second over a year are
oven-controlled crystal oscillators. I don't know how much they cost, but I
can refer you to John Vig's excellent tutorial
( Of course, commercial atomic standards
(rubidium, cesium, maser) can also do this, and I have purchased clocks with
rubidiums in them for a few K.

It can also be pointed out that any electric clock does this because the
line frequency is adjusted for this purpose. Also, any computer's clock
will do this if Network Time Protocol (NTP, is used, and any GPS receiver will do
this as well.

Demetrios Matsakis

> -----Original Message-----
> From: Steve Allen [mailto:sla_at_UCOLICK.ORG]
> Sent: Saturday, September 30, 2000 1:38 AM
> To:
> Subject: [LEAPSECS] consumer-quality clocks
> I've been delving through product literature on clocks, and this is
> what I've found. It looks as if the most accurate clocks that can
> affordably be obtained and embedded into devices whose principal
> purpose is not precision timekeeping are able on their own to keep
> time accurate to about one second per year. Leap seconds currently
> happen about once per year. This means that a standalone device
> cannot reasonably claim to be keeping either UTC or TAI without
> some mechanism for resetting the time.
> Does anyone know of affordable clocks which keep time for a year to
> an accuracy of better than one second?
> --
> Steve Allen UCO/Lick Observatory Santa Cruz, CA 95064
> Voice: +1 831 459 3046
> PGP: 1024/E46978C5 F6 78 D1 10 62 94 8F 2E 49 89 0E FE
> 26 B4 14 93
Received on Sat Sep 30 2000 - 14:12:06 PDT

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