From owner-freebsd-chat Wed May 3 16:17:21 2000 Delivered-To: freebsd-chat@freebsd.org Received: from shell.webmaster.com (mail.webmaster.com [209.133.28.73]) by hub.freebsd.org (Postfix) with ESMTP id 68A2937B68D for ; Wed, 3 May 2000 16:17:19 -0700 (PDT) (envelope-from davids@webmaster.com) Received: from whenever ([209.133.29.2]) by shell.webmaster.com (Post.Office MTA v3.5.3 release 223 ID# 0-12345L500S10000V35) with SMTP id com; Wed, 3 May 2000 16:17:18 -0700 From: "David Schwartz" To: "Matthew Hunt" Cc: Subject: RE: GPS heads up Date: Wed, 3 May 2000 16:17:17 -0700 Message-ID: <000501bfb555$b98ff450$021d85d1@youwant.to> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook 8.5, Build 4.71.2377.0 In-Reply-To: <20000503145930.B33563@wopr.caltech.edu> X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4029.2901 Importance: Normal Sender: owner-freebsd-chat@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > So, I will apply my meager knowledge of pulsar observations to > guess that the phase difference between the two frequencies gives > you the integral of the electron number density along the path, > and hence allows you to measure the delay introduced by the > ionosphere, and subtract it off? (I have read elsewhere that > the ionospheric fluctuations are the largest source of error, > aside from SA.) I was under the impression that after SA (which is now a thing of the past), the largest single source of error was that the satellites weren't precisely where they said they were. I remember reading about work to measure the position of the satellites to accuracies of fractions of a meter to eliminate this source of error. DS To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message