From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from snark.thyrsus.com (static-71-162-243-5.phlapa.fios.verizon.net [71.162.243.5]) by huchra.bufferbloat.net (Postfix) with ESMTP id EBBBD208A8C for ; Wed, 4 Apr 2012 06:36:37 -0700 (PDT) Received: by snark.thyrsus.com (Postfix, from userid 1000) id 48AE542E29; Wed, 4 Apr 2012 09:36:15 -0400 (EDT) Date: Wed, 4 Apr 2012 09:36:15 -0400 From: "Eric S. Raymond" To: Dave Taht Message-ID: <20120404133615.GA15404@thyrsus.com> References: <20120403143402.GA7338@thyrsus.com> <4F7B1041.4070303@techstarship.com> <20120403153518.GA7871@thyrsus.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Eric Conspiracy Secret Labs X-Eric-Conspiracy: There is no conspiracy User-Agent: Mutt/1.5.21 (2010-09-15) Cc: thumbgps-devel@lists.bufferbloat.net Subject: Re: [Thumbgps-devel] "Plain Jane" timing GPS is working! X-BeenThere: thumbgps-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list Reply-To: esr@thyrsus.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 Apr 2012 13:36:38 -0000 Dave Taht : > Expect light participation from me here through may 5. I would certainly be > open here to a discussion of 'now that we have good time, and geolocation, > what can we effectively measure with it, and with what tools'... Good time isn't quite a done deal yet. There are some relatively minor changes to gpsd and a bit more hardware testing between here and there. I'd say two weeks, assuming we don't run into any boojums. And I won't sign off that the job is *really* finished until we can document hard bounds on the jitter using something like the test rig Patrick Maupin is trying to build. By the way, I've had a third GPS vendor - a U.S. outfit called Parallax Systems - get back to me with interest in the Plain Jane timing-GPS mod (connect 1PPS to DCD in a stock design using SiRF+PL2303 or functional equivalents). Had a long, friendly phone conversation with one of their design guys. For those of you not paying full attention recently, I have engineering samples of Plain Jane from UniTraq - not yet verified that these work because I have to mod gpsd so it won't time out the PPS thread before it gets sat lock. Meanwhile, Unitraq's test engineers in Shenzhen have shown me a gpsd log including PPS events seen over USB. But we need to tell gpsd's noise filter to be a bit less picky; for some reason it doesn't like the pulse width and is rejecting those. So we have two vendors actively cooperating on Plain Jane product development and may have a third shortly. This is all good; my ideal outcome would be multiple sources, with other vendors starting to pick up that they need to supply 1PPS to stay competitive and it becoming a stock feature on all new low-end GPS mice within a year. Actually, it still kind of blows my mind that I've been able to social-engineer all this with a handful of emails. Woulda been the stuff of cyberpunk novels before the century turned... -- Eric S. Raymond