Joel McNamara

Joel McNamara is a writer, technology consultant, and outdoor adventurer. He has worked in the computer industry for 25 years and advises international humanitarian organizations on safety and security issues. Joel is also the author of Geocaching For Dummies and Secrets of Computer Espionage.

Articles & Books From Joel McNamara

Article / Updated 03-26-2016
When the U.S. government turned off GPS Selective Availability (SA) in May 2000, it was like magic. Suddenly civilian GPS receivers that were formerly accurate to about 300 feet were accurate to 30 feet. This level of accuracy offered some creative possibilities. Three days after SA was turned off, a message appeared in the sci.
GPS For Dummies
Need directions? Are you good at getting lost? Then GPS is just the technology you’ve dreamed of, and GPS For Dummies is what you need to help you make the most of it. If you have a GPS unit or plan to buy one, GPS For Dummies, 2nd Edition helps you compare GPS technologies, units, and uses. You’ll find out how to create and use digital maps and learn about waypoints, tracks, coordinate systems, and other key point to using GPS technology.