[time-nuts] 60 Hz measurement party

Poul-Henning Kamp phk at phk.freebsd.dk
Mon Jun 27 05:02:51 UTC 2011


In message <201106270013470285.1B239AEA at smtp.citynet.net>, "Will Matney" writes
:
>Here's another thought on all of this. How will this effect the newer
>electronic watthour meters at peoples homes? I remember looking at the
>schematics on one of these, and I don't remember seeing an internal time
>base, crystal, or resonator in the circuit, so I suppose they might get
>their timing from the 60 Hz line.

Modern microcontrollers contain a on-chip resonator, typically 8MHz,
which is surprisingly stable, often a lot more stable than the mains
frequency.

Electricity meters are usually only precise to 1 or 2%.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
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Never attribute to malice what can adequately be explained by incompetence.




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