NIST NTP servers

Thu May 12 17:19:39 UTC 2016

On 2016-05-11 10:30, Mel Beckman wrote:

> Read deeper into the thread and you'll find where I sourced inexpensive RF-based NTP servers using CDMA, GSM, and even WWV. 

For shortwave, you would need to calculate propagation delay between
transmitter and receiver. (does signal reach via line of sight, bounce
against ionosphere ?).

Since CDMA is dead outside the USA and drying in USA, I wouldn't rely on
that.  If GSM towers rely on a GPS receiver on the tower and those
towers are near enough to your location (< 30km), then chances are that
blocked GPS signals at your location would also jam the signals at the
GSM antenna.

And if you are setup to be totally autonomous in case of power failures,
you need to know whether the GSM antenna you are relying on is also on
permanent power backup or only has autonomy of a few hours.