[189250] in North American Network Operators' Group
Re: NIST NTP servers
daemon@ATHENA.MIT.EDU (Mel Beckman)
Thu May 12 14:09:58 2016
X-Original-To: Nanog@nanog.org
From: Mel Beckman <mel@beckman.org>
To: Jean-Francois Mezei <jfmezei_nanog@vaxination.ca>
Date: Thu, 12 May 2016 18:09:52 +0000
In-Reply-To: <5734BB2B.6030307@vaxination.ca>
Cc: "Nanog@nanog.org" <Nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
The WWV signal is still accurate within a few milliseconds. Light is fast. =
Really fast.
-mel
> On May 12, 2016, at 10:19 AM, Jean-Francois Mezei <jfmezei_nanog@vaxinati=
on.ca> wrote:
>=20
> On 2016-05-11 10:30, Mel Beckman wrote:
>=20
>> Read deeper into the thread and you'll find where I sourced inexpensive =
RF-based NTP servers using CDMA, GSM, and even WWV.=20
>=20
> For shortwave, you would need to calculate propagation delay between
> transmitter and receiver. (does signal reach via line of sight, bounce
> against ionosphere ?).
>=20
> 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.
>=20
> 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.
