From owner-freebsd-current Thu Dec 16 12:32:56 1999 Delivered-To: freebsd-current@freebsd.org Received: from rover.village.org (rover.village.org [204.144.255.49]) by hub.freebsd.org (Postfix) with ESMTP id 70A7015017 for ; Thu, 16 Dec 1999 12:32:54 -0800 (PST) (envelope-from imp@harmony.village.org) Received: from harmony.village.org (harmony.village.org [10.0.0.6]) by rover.village.org (8.9.3/8.9.3) with ESMTP id NAA92548; Thu, 16 Dec 1999 13:32:53 -0700 (MST) (envelope-from imp@harmony.village.org) Received: from harmony.village.org (localhost.village.org [127.0.0.1]) by harmony.village.org (8.9.3/8.8.3) with ESMTP id NAA73759; Thu, 16 Dec 1999 13:32:52 -0700 (MST) Message-Id: <199912162032.NAA73759@harmony.village.org> To: nate@mt.sri.com (Nate Williams) Subject: Re: HEADSUP: ntp4 to replace xntpd Cc: "FreeBSD Current Users' list" In-reply-to: Your message of "Thu, 16 Dec 1999 11:10:45 MST." <199912161810.LAA19919@mt.sri.com> References: <199912161810.LAA19919@mt.sri.com> <16818.945366687@critter.freebsd.dk> Date: Thu, 16 Dec 1999 13:32:52 -0700 From: Warner Losh Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG In message <199912161810.LAA19919@mt.sri.com> Nate Williams writes: : You may not know the answer to this, but it's worth a shot. Wht kind of : accuracy can we expect using 'cheap' off-the-shelf GPS receivers? We're getting, with ntp4 on a 3.x kernel, about +- 4uSec with a cheap gps receiver + atomic clock on a i486 class machine. The clock doesn't want to sync more closely than that, likely due to the large jitter in the 8254 timing device, so the atomic clock is a bit of a waste for this part of our application (there are others it is needed for). With a pentium class machine and w/o the atomic clock "backing", I'd say you could easily get into the sub-micro second range. Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message