[EAS] Homeland Security Staff locked out of computers?

[Tim Stoffel]

NIST has hydrogen MASER clocks as their reference. I suspect they will be replacing these with the recently developed Ytterbium clocks, which currently are the most accurate clocks known. I don't know what USNO uses, but I bet the USNO's clocks are ultimately based on NIST's clocks.

It seems strange that WWV would base its clocks on the color subcarrier of a TV station, even though the subcarrier of the network stations were ultimately derived from an atomic clock (63/88 X 5 MHz = 3579545.45454545..... Hz). I would guess these atomic clocks are located in the NOC's on the east and west coast, and got to Denver indirectly. Different sync generators along the way would add jitter or even outright error, should they become unlocked to network for whatever reason.

Atomic clocks were expensive, exotic devices in those days. Today, you can get them new for under $1,000 (Symmetricomm's chip scale Cesium clock), or used Rubidium clocks on EBAY for well under $100.

Tim Stoffel

-----Original Message-----
From: EAS [mailto:eas-bounces at radiolists.net] On Behalf Of Botterell, Arthur at CalOES

Many years back I visited WWV.  At that time they sync'd their on-site clock with the one down at the (then) Bureau of Standards office down in Boulder by getting a stream of correction data relative to the color subcarrier of one of the Denver TV stations.