From owner-freebsd-questions Wed Jan 31 10:16:20 1996 Return-Path: owner-questions Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id KAA23776 for questions-outgoing; Wed, 31 Jan 1996 10:16:20 -0800 (PST) Received: from phaeton.artisoft.com (phaeton.Artisoft.COM [198.17.250.211]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id KAA23769 for ; Wed, 31 Jan 1996 10:16:18 -0800 (PST) Received: (from terry@localhost) by phaeton.artisoft.com (8.6.11/8.6.9) id LAA10118; Wed, 31 Jan 1996 11:12:43 -0700 From: Terry Lambert Message-Id: <199601311812.LAA10118@phaeton.artisoft.com> Subject: Re: good NTP servers To: pete@pelican.com (Pete Carah) Date: Wed, 31 Jan 1996 11:12:42 -0700 (MST) Cc: questions@FreeBSD.org In-Reply-To: from "Pete Carah" at Jan 31, 96 00:09:00 am X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-questions@FreeBSD.org Precedence: bulk > USNO are *not* _using_ gps; it's the other way around. They feed the > gps system its sync (probably via the USAF). How are they syncing Cesium clocks at multiple locations? There are relativistic effects from moving a presynced clock, running two clocks at different gravities (altitude/surface mass density) and angular rotation rates (lattitude, and altitude again: distance from axis of rotation). They *must* sync by knowing relative position and relative sync differential based on local relativistic effects in the sync source and destination. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.