From owner-freebsd-questions@FreeBSD.ORG Sat Sep 20 05:09:50 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2F9211065684 for ; Sat, 20 Sep 2008 05:09:50 +0000 (UTC) (envelope-from tom@snnap.net) Received: from building.adl.snnap.net (unknown [IPv6:2001:44b8:62:10::10]) by mx1.freebsd.org (Postfix) with ESMTP id A220A8FC13 for ; Sat, 20 Sep 2008 05:09:49 +0000 (UTC) (envelope-from tom@snnap.net) Received: from atom.wireless.snnap.net (unknown [IPv6:2001:44b8:62:11:21e:52ff:fe73:74e9]) by building.adl.snnap.net (Postfix) with ESMTP id 41DCA117F0; Sat, 20 Sep 2008 14:39:48 +0930 (CST) Message-Id: From: Tom Storey To: Bob Johnson In-Reply-To: <54db43990809191539l558faaa3qc6b4f42d8090569e@mail.gmail.com> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v926) Date: Sat, 20 Sep 2008 14:39:48 +0930 References: <57037.172.25.144.4.1221827796.squirrel@imap.snnap.net> <54db43990809191539l558faaa3qc6b4f42d8090569e@mail.gmail.com> X-Mailer: Apple Mail (2.926) Cc: freebsd-questions@freebsd.org Subject: Re: ntpd and GPS X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 20 Sep 2008 05:09:50 -0000 Ok, it was nothing like what I was thinking. Turns out my GPS didnt have a fix on anything. It was getting signals, but no fix. :-) Now that I have it mounted on a pole outside, hey presto: building# ntpq -p remote refid st t when poll reach delay offset jitter = = = = = = ======================================================================== +resolv.internod 128.250.33.242 2 u 50 64 377 18.121 -1.127 14.549 *sparky.services 131.203.16.6 2 u 56 64 377 21.275 -9.704 15.235 GPS_NMEA(0) .GPS. 0 l 3 64 1 0.000 -442.78 0.002 Cheers for your help. I'll keep tweaking it now until I get it working just right (jitter is incrementing and Im sure thats not a good thing). Tom On 20/09/2008, at 8:09 AM, Bob Johnson wrote: > On 9/19/08, Tom Storey wrote: >> Hi all, >> >> Ive been toying with setting up my old Garmin GPS12 as a reference >> for a >> server (FreeBSD 6.2) running ntpd, but Ive run into an issue. >> > > Is it possible the issue isn't what you think it is? > >> Ive searched around a bit and cant find an answer, perhaps because >> there >> isnt one. > > I once (years ago) had a Garmin GPS working with ntpd, so it's > reasonable to believe it can be done again, unless support for that > capability was dropped (which I doubt). Unfortunately, it was long > enough ago that I don't remember what I did. It's possible I used the > 1 PPS output without NMEA sentences, but that's not my recollection. > >> >> Is there any way I can set ntpd to expect a $GPRMC string every 2 >> seconds, >> which is the frequency at which the GPS12 transmits them? >> > >> Alternatively, does anyone know how to make the GPS12 transmit a >> $GPRMC >> string every second? > > I'm almost certain you can't. The complete set of all NMEA sentences > takes more than one second at the default 4800 baud, so IIRC it > outputs sentences only on odd seconds, and perhaps the older units are > too slow to compute a fix once per second. Two things that may work > around this are to turn off everything except the GPRMC sentence: > > $PGRMO,,2 > $PGRMO,GPRMC,1 > > and perhaps free up some CPU time (for faster position calculation) by > (oddly enough) reducing the output data rate to 1200 bps: > > $PGRMC,,,,,,,,,,1, > > but I don't think that will actually work. To go back to 4800 bps, use > 3 instead of 1. I think there are 11 commas after the "C" in that > command, but my eyes aren't so sharp any more. > > There is a Linux driver for the Garmin proprietary protocol. Don't > know if it is distributed in a FreeBSD version. Try > http://jensar.us/~bob/garmin/ > >> >> If there is a better place I can post this, please let me know. > > This is probably a good place for this question, but if you don't get > a better answer, try the archives of the "time nuts" mailing list > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts which > unfortunately appears to be down right now. General info about that > group is at http://www.leapsecond.com/time-nuts.htm > > If that yields nothing, you might post your question to the Time Nuts > list, time-nuts @ febo.com. It is probably a FAQ for them, but they > will be polite about it. And I had hoped to once again stick an old > Garmin on an NTP server, so I'll be curious to know if this turns out > to be insurmountable. > > Good luck, > > -- Bob Johnson > fbsdlists@gmail.com