From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.perfora.net (mout.perfora.net [74.208.4.195]) by huchra.bufferbloat.net (Postfix) with ESMTP id 9B3CC20019D for ; Thu, 15 Mar 2012 07:52:34 -0700 (PDT) Received: from [192.168.83.5] (c-76-97-152-51.hsd1.ga.comcast.net [76.97.152.51]) by mrelay.perfora.net (node=mrus2) with ESMTP (Nemesis) id 0MUHYA-1RhLW63Wra-00Qefp; Thu, 15 Mar 2012 10:52:34 -0400 Message-ID: <4F62022C.6020901@c3energy.com> Date: Thu, 15 Mar 2012 10:52:28 -0400 From: "Ron Frazier (NTP)" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.9) Gecko/20100722 Eudora/3.0.4 MIME-Version: 1.0 CC: thumbgps-devel@lists.bufferbloat.net References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V02:K0:56694hy8u2ALaEgsb5fMpGUWckT/QDn/xo38CDS8HdH epn35YDwgcTk+SyrFt9lux5sjTOgqKeHbj2UhVZUAns90DRU2/ vjkrz4gfUf/hridp116XEhL0X7+GiKLeXyh+Uuyhd7qbQmJJ8z vr+la+WWYwPXmCXQ5G4HH/I0yAAi5nlcgxUv+e2/LKl0lQL7jX 1MGseQHqH9QhYgWUEF/9FXeJxsbFwFlD75/VQyKqXZH2AI9Y/J F+f00hUMezZyOKJHV8i2ckmA3vWdeM3GZr8djq49TpbYx8oNju l0e+r2FsGa6bheXbCrrX+pidQoabF/9ohXIEr7HEYZ0BhFM0RR 5byNzeSjMJ6vxpIR12e4Pb2yV0fo72XuZzTONTdbZ Subject: Re: [Thumbgps-devel] USB handshake signals and Linux X-BeenThere: thumbgps-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Mar 2012 14:52:35 -0000 I have a question about GPSD. I have nothing against it, but why is it necessary to use it at all? I have NTPD running on both Windows and Linux, and reading my GPS. GSPD isn't available on Windows as far as I know. What does using GPSD get me that running without it does not? Sincerely, Ron On 3/15/2012 10:37 AM, tz wrote: > > Skytraq has a number of unique commands that identify the chipsets. > So do MTK and Garmin. > > Right now the udev for gpsd gets it wrong by including the generic > FTDI vendor id for one gps, so plugging in my ftdi arduino/breakout > starts up gpsd and it probes (same error in upowerd - I filed a bug > report with fedora). It thought my SkyTraq was this unit. > > I have the PPS hooked to the CTS pin, but gpsd has to be recompiled to > enable pps or change pins. This should be configurable at runtime. > > You still have the same problem using any other gps for bufferbloat - > gpsd will attempt to sync the time via ntpshm based on any NMEA stream > at the last sentence in a group. You will need some tweaking to make > it not do this, or reject other gps units, or otherwise indicate that > unless you are using one of our 'blessed' units the time won't be > accurate. 'Blessed' might mean PPS, but how do we certify it? > > How much of an issue will this be? If we are going to require using > one specific hardware combo, it will have the right set for > gpsd-ntpd-kernel. If we allow any configuration of any hardware or > software, we have no way of verifying it has precise UTC time - when > was the last PPS, has the correction in adjtime caught up, etc. though > that applies to ours too. > > -- (PS - If you email me and don't get a quick response, don't be concerned. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new messages very quickly. If you need a reply and have not heard from me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude AT c3energy.com