The receivers and methods of GPS are constantly evolving and changing. There are, nevertheless, some well established principles. Some of those have been explained in this lesson.
There is another principle. GPS is a geodetic system. It is not possible to understand it without some understanding of geodesy - the subject of the next lesson. As a matter of fact, it isn’t hard to operate a GPS receiver - most of them are so user friendly you don’t need to know the first thing about GPS to make them work, that is, until they don’t.
Getting coordinates from a GPS receiver is usually a matter of pushing a few buttons, but knowing what those coordinates are, and more importantly, what they aren’t, is more difficult. It is vital to have an idea of how the values were measured; otherwise you are at the mercy of the black box, and since it doesn’t always tell the truth, that’s not a good idea.
Before you go on to Lesson 5, double-check the Lesson 4 Checklist to make sure you have completed all of the activities listed there.