Saturday, December 29, 2012

GPS Made Easy

Find Yourself Anywhere In The World - GPS Made Easy by Lawrence Letham and Alex Letham

Have a GPS (Global Positioning System) and don’t really know what do with it or thinking about getting a GPS receiver but don’t have any experience with GPS? 

Then get your hands on a copy of GPS Made Easy

In GPS Made Easy, Lawrence Letham provides a good overview of the GPS system and how to use GPS in the outdoors. The book is written for people without any GPS experience and breaks down GPS into its components and its various uses. 

Starting with an introduction to global positioning, Letham provides a simple and great explanation of the constellation of satellites that orbit the Earth that can provide location information with an error of only between 15 to 100 meters. This kind of accuracy, anywhere on the face of the Earth at any time and in any weather, makes GPS an excellent addition to any outdoorsperson’s toolkit. 

15 to 100 meter accuracy isn’t that good you say? Often GPS accuracy is higher than that, down to a few meters, however due to the government’s “selective availability” policy, civilian GPS receivers have a certain amount of error built in, usually several meters. The accuracy all depends on how many satellites your receiver can connect to and the dynamics of your location. But on the whole, even at 100-meter accuracy (300 feet), you should have no problems in navigating and locating various areas. Horizontal sub-meter accuracy is generally only needed in precise surveying work. 

Following an overview of the GPS system and the history of navigational aides, Letham delves into more of the intricacies of using a GPS system. These include a review of GPS receivers that are available and how to convert and work with UTM coordinates (the coordinate system that GPS uses, as opposed to the more well-known latitude and longitude system). 

The next several chapters deal with using GPS in various situations and provide examples of how the GPS can help with outdoor adventures. The real world examples include navigation in a whiteout, figuring out latitude and longitude on a kayak trip and on a sailboat rally, using GPS with small scale maps on a road trip, and recovering from the loss of a GPS receiver while in the outdoors. These examples are good to read because they cover many of the areas that people will find themselves in (well I don’t compete in sailboat rallies, but you get the point) and by seeing how to use GPS (or in the last case, navigate without GPS), you will have a better handle on what GPS can do and what its limitations are. 

After the examples, Letham reviews how GPS receivers can work with personal computers. This book was written before the advent of many handhelds – but the concepts introduced with computers are applicable to today’s generation of handhelds and laptops. This includes real-time mapping and navigation (where you basically see yourself on a map on the handheld or laptop) and logging of the point information you are saving in the GPS. 

Letham closes GPS Made Easy, with discussions on other coordinate grids that are sometimes used in GPS and navigation and an introduction to differential GPS and a discussion of degrees, minutes and seconds in the latitude and longitude system (since the accuracy of GPS can be down to seconds and even mils at times). 

GPS Made Easy contains a well rounded glossary that defines many of the more technical terms used throughout the book, a list of resources and other books on GPS systems, and a checklist of information to look for in your GPS receiver. 

Anyone unfamiliar with the inner workings of GPS or with their own GPS receiver would be better off with a copy of GPS Made Easy - it is a great introduction to the world of GPS based navigation and is clearly written with the novice in mind. 

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