Information in the article that appears in the current issue of the online hacker magazine Phrack potentially puts at risk GPS devices used for commercial navigation and military operations, authorities said.

The Phrack article provides a detailed guide to building a low-cost, portable GPS jammer out of components that can be easily obtained from electronics supply houses. According to the article, the "onslaught of cheap GPS-based navigation (or hidden tracking devices) has made it necessary for the average citizen to take up the fine art of electronic warfare." Electronics and GPS experts who read the article this week called it technically competent and said amateurs with a certain amount of technical skill could build a GPS jammer from the plans.

Homemade GPS jammers raise concerns - Computerworld