From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ip-64-139-1-69.sjc.megapath.net (ip-64-139-1-69.sjc.megapath.net [64.139.1.69]) by huchra.bufferbloat.net (Postfix) with ESMTP id A65A9202103 for ; Wed, 2 May 2012 00:58:09 -0700 (PDT) Received: from shuksan (localhost [127.0.0.1]) by ip-64-139-1-69.sjc.megapath.net (Postfix) with ESMTP id 6CC7880003B; Wed, 2 May 2012 00:58:08 -0700 (PDT) X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.3 To: esr@thyrsus.com From: Hal Murray In-Reply-To: Message from "Eric S. Raymond" of "Tue, 01 May 2012 23:33:45 EDT." <20120502033345.GA11913@thyrsus.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 02 May 2012 00:58:08 -0700 Message-Id: <20120502075808.6CC7880003B@ip-64-139-1-69.sjc.megapath.net> X-Mailman-Approved-At: Wed, 02 May 2012 01:06:13 -0700 Cc: thumbgps-devel@lists.bufferbloat.net, hmurray@megapathdsl.net, gpsd-dev@nongnu.org Subject: Re: [Thumbgps-devel] [gpsd-dev] PPS over USB 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: Wed, 02 May 2012 07:58:10 -0000 esr@thyrsus.com said: > Clock time should be OK even with a single sat - multiple birds are needed > for the spherical trig to compute position, but atomic time you get directly > from each sat sample. I think it's more complicated than that. You can get time with only 1 sat if know where you are located. It takes special software, usually called "timing". The usual approach for finding the location is to do a "survey". That requires more special software which is usually included in the timing package. It collects a 1000 (or whatever) good samples and averages the position. The "good" qualifier means they don't use low-quality samples which might be way off. It's worth asking Navisys if they have the timing mode software. -- These are my opinions, not necessarily my employer's. I hate spam.