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Author Topic: Atomic clock propagation question?  (Read 1082 times)
K5DVW
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Posts: 2193




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« Reply #15 on: February 05, 2009, 06:19:15 AM »


Atomic clocks are not based on the decay rate of Cs, it's the microwave resonance frequency of some element that is divided down to provide second ticks. Could be Cs, could be Rb, could be Sr. It's not the decay rate, that's something entirely different. Decay rate is used in things with a huge time span and large errors like carbon dating.

They're called atomic clocks because they rely on one atomic element. Nothing to do with radioactivity.

And, as far as I know, unless there is a new technology I dont know about, these watches are not GPS based but use WWBV at 60KHz. GPS would be a nice way to do it, albeit still too power hungry for the tiny batteries in a watch. Cell phones use GPS, but usually not directly. They reset to the master clock in the cell site which is locked to GPS.

I suspect you'd find a resonant ferrite rod antenna in the watch, much like in your AM radio. Those kind of flux antennas are actually pretty good for their size and that's why you dont need some mondo-huge antenna to pick up 60KHz. They are directional, which means it matters how you orient your watch!

Anyway, the problem at hand is probably one of propagation failure due to atmospheric conditions or poor placement of the device or local interference. You pick it!
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AA4M
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« Reply #16 on: February 05, 2009, 06:49:30 AM »

This is a great thread . . . nobody is flaming anyone, I've learned new stuff, I like it - hi!

73, Bill
AA4M
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WA3SKN
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« Reply #17 on: February 05, 2009, 09:23:14 AM »

I just found out there are two styles of atomic clocks... one synced off GPS, the other-more common, synced off 60Khz WWVB!  Learn something new every day!

-Mike.
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