On Mon, 20 Dec 2010, Ethan Dicks wrote: >> as a side node, above makes me wonder a bit on how accurate the timing of the >> 50Hz interrupt really is (or could be even, since the power line frequency >> isnt exactly stable) > >> From moment to moment, 50Hz (or 60Hz in the States) can be off by a > small amount due to load on the grid, but over 24 hours, in the States > at least, you should see something like 4320000 (5184000) total ticks > with close accuracy. They do (here at least) tweak the total number > of ticks in one day to keep mains-powered alarm clocks accurate. > Without active compensation, system load would throw seconds or > minutes per day of inaccuracy into any clock that depended on mains > frequency. The voltage-current phase may vary slightly under local load, but the frequency timing is very accurate. It has to be, since many power generation plants are connected together in large grids. Any variation in the frequency would result in power loss and overheating in the transmission lines. wlevak@sdf.lonestar.org SDF Public Access UNIX System - http://sdf.lonestar.org Message was sent through the cbm-hackers mailing listReceived on 2010-12-21 06:00:05
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