NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Averaging
From: Alexandre Eremenko
Date: 2004 Nov 5, 22:25 -0500
From: Alexandre Eremenko
Date: 2004 Nov 5, 22:25 -0500
Dear Herbert, I am beginning to suspect that we are just talking about different things. I repeat the setting. We were discussing, say 3 observations of ONE body's altitude, spread over 5 minutes. You cannot obtain a FIX from these data. This will be a VERY BAD fix if you try. To obtain a fix from one body altitudes you have to SPREAD your observations in time, so that the azymuth changes MUCH. From 3 observations spread over 5 minutes you can obtain ONE position line. Not a fix. On Fri, 5 Nov 2004, Herbert Prinz wrote: > I want nothing of the sort. As I said, my equation M * x = a refers to any > system of linear equations. In the problem in hand, these represent LOPs > and the solution of the system is the FIX. > Have you actually looked at the algorithm in the N.A.? > Have you looked at > the articles in the Navigation Journal? That's what I am proposing. Unfortunately, I do not have access to this journal. And from your messages I cannot determine what situation is really described in these papers. Alex. P.S. Maybe they are talking about observing more than two bodies, say 3 stars, and how to make a fix from such observations? I don't think least squares are really needed in this situation, but certainly people who like computers and do not like drawing can do this. But this is a totally different situation from what I was talking about. I was talking all the time of ONE body observations over SHORT time. I never proposed averaging anything else:-)