From owner-freebsd-questions@FreeBSD.ORG Wed Apr 23 14:36:12 2003 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A7D7437B401 for ; Wed, 23 Apr 2003 14:36:12 -0700 (PDT) Received: from wasp.eng.ufl.edu (wasp.eng.ufl.edu [128.227.116.1]) by mx1.FreeBSD.org (Postfix) with ESMTP id CD88C43FDD for ; Wed, 23 Apr 2003 14:36:09 -0700 (PDT) (envelope-from bob88@eng.ufl.edu) Received: from eng.ufl.edu (scanner.engnet.ufl.edu [128.227.152.221]) by wasp.eng.ufl.edu (8.9.3p2/8.9.3) with ESMTP id RAA16864; Wed, 23 Apr 2003 17:36:05 -0400 (EDT) Message-ID: <3EA70744.4090805@eng.ufl.edu> Date: Wed, 23 Apr 2003 17:36:04 -0400 From: Bob Johnson User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.3b) Gecko/20030318 X-Accept-Language: en-us, en MIME-Version: 1.0 To: dkelly@hiwaay.net, FreeBSD-Questions@freebsd.org Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: Accurate time without a network connection? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Apr 2003 21:36:13 -0000 > Date: Wed, 23 Apr 2003 11:13:58 -0500 > From: David Kelly > Subject: Re: Accurate time without a network connection? > To: Joel Rees > Cc: FreeBSD-Questions@freebsd.org > Message-ID: <20030423161358.GA24633@grumpy.dyndns.org> > Content-Type: text/plain; charset=us-ascii > > On Wed, Apr 23, 2003 at 05:58:47PM +0900, Joel Rees wrote: > >>>> > On Tue, Apr 22, 2003 at 03:26:19PM -0400, Charles Swiger wrote: >>>> > >>>> > As for exactly what time the systems have, it doesn't much matter as >>>> > long as they all have the same time. >> >>> >>> If you're serious about it not mattering exactly what time they have, >>> what's the problem with letting one machine be the time server, letting >>> it tune itself and then free run, and syncing all the rest to the >>> slightly-off-time-server? > > > Because the other systems do not have a link to the first. > > I could sync them all to a common source they could *hear* but the > customer won't allow them to *talk* to anything. > > - David Kelly N4HHE, dkelly@hiwaay.net > The NTP daemon can sync to a variety of external time signals. These days it is very common to use GPS receivers as the reference for an NTP server. If you can afford to spend about $100 per computer for low end GPS receivers (that output NMEA-0183 data) AND it is possible to put each GPS receiver where it can see the sky, that should work for you. If all of the computers are in the same building, it may even be possible to have them share a common GPS receiver with appropriate cabling. There are other options, but I don't remember what they are. For instance, it might be possible to sync the computers to the time reference included with most network television signals. See www.ntp.org for more clues. - Bob