As of May 02, 2000 Selective Availability (SA) has been discontinued.
We have not had a chance to update all of the articles, so please simply disregard any mention of it, but be aware that other sources of error still exist.
This article is targeted for campers, hikers, backpackers, hunters, and anyone else who enjoys being in the out of doors. It assumes that you know nearly nothing about using a map and/or a compass. As a physics teacher, I know that there are many of you who are not proficient in these skills, because I find that 95% of my students have no idea how a compass works, much less how to use it for simple navigating. With this caveat in place, let's look at some of the things you need to know to begin basic navigation on land.
This guide is targeted for all outdoor enthusiasts who want to step into GPS, but don’t know much about it. My intension is to share some basic working knowledge of GPS without dwelling on all the whys, ifs, or the science behind it. The techniques described are certainly not the only ones, but they serve me well. I hope that they will be helpful to you, the reader. A basic knowledge of topographical maps and compass is recommended, in order to fully benefit from using a GPS. Ron Wilson takes the mystery out of it in his “Maps, Compasses, & GPS's 101” article. For the uninitiated, I recommend reading his article first. Don’t worry if you don’t remember everything right away. Links in this guide will point you to relevant sections of Ron’s article. To easily navigate between the two, if you want to follow a link, open it in a new window (“right click” in IE). Illustrations used are the actual screen dumps from a Lowrance GlobalMap 100 receiver, but the basic functions described can be found in other brands of GPS receivers. The manual that came with your unit will tell you which keys to punch.
Part 1 - “The Bad News about GPS” deals with some basic concepts and limitations. These are things you really need to know about the system.
Part 2 - “The Good News about GPS” guides you through some practical applications of GPS in outdoor recreation and ways of dealing with the system limitations.
Part 3 – “A Little GPS that could” guides through creation of a basic reference map which can be displayed by a “non mapping” unit.