[time-nuts] Measuring the accurcy of a wrist watch

Brooke Clarke brooke at pacific.net
Thu Apr 17 23:33:37 UTC 2014


Somewhere here I have a page from a magazine showing a resonant tank circuit at 32768 Hz where the coil is maybe a few 
inches in diameter.
You set any watch running at that frequency and it can count the oscillations.
Rather than adjusting the rate to be spot on, the suggestion is to know the rate of the watch in normal use over a week 
and then make a proportional adjustment in the rate.

I can see the crystals used in various electronics boxes by attaching their BNC connector to the HP 4395A used as a 
spectrum analyzer.
For example in the drop zone assembly aid system receiver you can see the local oscillator frequency by connecting the 
receive antenna terminal to the SA.

This works because the 4395A uses a DSP based IF system including true Resolution Band Width filters down to 1 Hz which 
makes for a very low noise floor.

Have Fun,

Brooke Clarke

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