[time-nuts] Question for the cesium nuts.
SAIDJACK at aol.com
SAIDJACK at aol.com
Fri Mar 16 22:59:25 EDT 2007
In a message dated 3/16/2007 18:32:58 Pacific Daylight Time,
martelno at yahoo.com writes:
Also, some high end rubidium (such as Perkin-Elmer)
manufacturers are able to develope 133Rb clocks having
> 450 000 hours MTBF! That'a a lot of nanoseconds!
Hi Jack,
we cannot expect the units to work that long. Hard Disks have >50K MTBF, and
fail all the time in much less time depending on how they are used etc.
MTBF is a mean, meaning in the real world the Perkin Elmer unit could fail
in the first 10 minutes, just that the statistics for that to happen have
pretty low probability.
When they calculate MTBF, they probably don't take into account external
effects such as AC voltage spikes due to janitors pluggin-in vacuum's or due to
lightning etc, earthquakes, user obuse, water damage, movement, effects of UV
light on plastik parts such as cables, Tin Whisker shorts, electrolytic
capacitor dryout, mouse damage, etc. I think it's pretty useless to say a piece
of equipment has a MTBF of over 50 years. Then again that's only an opinion...
bye,
Said
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