[time-nuts] What is "accuracy"? (newbie timenut, hi folks!)
Hal Murray
hmurray at megapathdsl.net
Fri May 6 00:51:21 EDT 2016
catgirl at bordernet.com.au said:
> What I am trying to understand is, what does it REALLY mean when the
> manufacturer's specs for a frequency standard or 'clock' claim a certain
> accuracy. For ease and argument's sake let us assume that the accuracy is
> given as 100 ppm or 1e-4 ....
...
> But does that mean that, say, after one day I can be certain that my clock
> will be fast/slow by no more than 8.64 seconds or could it potentially be
> greater than that? ...
You have to read the data sheet, including the fine print.
For low-cost oscillator packages, there is a simple spec like "50 ppm" that
covers everything. It will be within spec if your power supply and
temperature are within specs. It will still be within spec after N years,
but they usually don't specify that.
For expensive oscillators, the fine print gets interesting. There are
usually specs for aging rate and warm up time.
--
These are my opinions. I hate spam.
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