Re: ATM Synching to atomic clock via SNTP...

[David McCarter <mccarterd@claven.fanshawec.on.ca>]

>You can do a gross check with a WWV receiver.  Due to multipath propagation
>delays it's not as good as GPS, but well into the sub-second range.

The best radio based time service is from WWVB, which is on 60KHz. Because
of the very low frequency the radio propagation is along the earth's
surface, and the ionosphere plays a small part. There is a clock advertized
in Scientific American which incorporates a 60KHz receiver and data decoder
to keep the clock set quite accurately.

Or, some years ago I was at the Algonquin Radio Observatory, and saw a
Hydrogen Maser clock which was synchronized with the clocks at other radio
observatories via the GPS system. They were doing long base line radio
interferometry. Really Neat!  And accurate. I wish I knew more details.

For timing I have two WWV radios, one tuned to 5MHz and one tuned to 10MHz.
One is always getting a strong enough signal to provide the time. Sometimes
it's the WWVH transmission from Hawaii, which of course has a few
microseconds increased time delay.

Dave