From owner-freebsd-hackers Sat May 4 07:44:35 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id HAA08950 for hackers-outgoing; Sat, 4 May 1996 07:44:35 -0700 (PDT) Received: from tfs.com (tfs.com [140.145.250.1]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id HAA08944 for ; Sat, 4 May 1996 07:44:31 -0700 (PDT) Received: from critter.tfs.com by tfs.com (smail3.1.28.1) with SMTP id m0uFiZJ-0003xcC; Sat, 4 May 96 07:44 PDT Received: from localhost (localhost [127.0.0.1]) by critter.tfs.com (8.7.5/8.6.12) with SMTP id OAA05651; Sat, 4 May 1996 14:44:14 GMT X-Authentication-Warning: critter.tfs.com: Host localhost [127.0.0.1] didn't use HELO protocol To: hackers@freebsd.org cc: thorinn@diku.dk Subject: DCF77 + xntpd + freebsd = WOW! Date: Sat, 04 May 1996 14:44:12 +0000 Message-ID: <5649.831221052@critter.tfs.com> From: Poul-Henning Kamp Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk (thorinn: please forward to any interested parties in the NTP club) DCF77 is a 77.5 Khz radio-xmitter close to Frankfurt in Germany, which is probably a little over a thousand kilometers from where I live. I have a receiver for this station hooked up via a serial port to my P5/133 box running FreeBSD-current, I use the "siointrts" interrupt entry for this port to provide the precise timestamp xntpd needs. I have saved the peerstats and loopstats files since some time last november, and now I finally got around to run some stats on them. Here is the result: Clock-offset less than +/- 5ms: 97.8623 % Clock-offset less than +/- 2ms: 94.5631 % Clock-offset less than +/- 1ms: 80.0504 % Clock-offset less than +/- 500us: 65.6242 % The histogram of these offsets is a near-perfect bell-curve... Here then is the punchline: That receiver cost me something like 40 DMK via mail-order from "Konrad Electronic". Who said precise time-keeping had to be expensive ? :-) Poul-Henning Kamp