Re: [LEAPSECS] Diagram of CHU Leap-Second Recording and "Atomic" Clock

From: Poul-Henning Kamp <>
Date: Wed, 04 Jan 2006 21:35:06 +0100

In message <000301c61169$ee06d020$9515f204_at_computer>, Tom Van Baak writes:

>As for your Skyscan clock, I have several dozen
>similar consumer RC clocks here and none has
>ever adjusted itself for a leap second in real-time

The majority of such clocks only run the receiver for some part of
the day to save power.

One particular kind I examined ran the receiver until it had sync,
then powered the receiver down for 23 hours and repeated the cycle.

My local clockaholic told me that some of the more modern ones
sleep based on battery voltage: As the voltage drops, the chance
of slips in the mechanism increases and the receiver will turn on
more often to make sure it is still in sync.

In the case of DCF77, that means that you'd have to be rather lucky
for your clock to do the leapsecond in real time.


Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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Received on Wed Jan 04 2006 - 12:46:13 PST

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