On 14/01/2015 17:37, Grant Edwards wrote:
On 2015-01-14, Mark Lawrence <breamore...@yahoo.co.uk> wrote:
On 14/01/2015 16:33, Dave Angel wrote:
Note that neither Timer nor sleep makes any promises about how
accurately it matches the requested time.
Reminds me of working on Telematics S200/300/4000/5000 telecomms kit in
the early 90s where the timers were mains based, so a one hour timer
would go off at about one hour, 30 seconds.
I don't understand. Power line frequencies are _very_ accurate and
have been relied upon for timekeeping since the 1930s. We're talking
a few hundred PPM over a 24 hour period. A 30 second error over a one
hour period seems _really_ high.
From
http://www2.nationalgrid.com/uk/services/balancing-services/frequency-response/
"National Grid has a licence obligation to control frequency within the
limits specified in the 'Electricity Supply Regulations', i.e. ±1% of
nominal system frequency (50.00Hz) save in abnormal or exceptional
circumstances.". I wouldn't describe ±1% as very accurate and certainly
not within a few hundred ppm. I'm assuming that this kind of limitation
applies around the world, so could you be getting confused with some
other more accurate frequency control?
--
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.
Mark Lawrence
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