GPS Devices and Personal Privacy Issues

Introduction

The GPS is, in essence, a data production technology, because its fundamental role is to produce the coordinate location of a receiver. With the addition of differential GPS and the Wide Area Augmentation System (WAAS), receivers can yield ground coordinates within fractions of an inch of their true position. GPS satellites were initially launched by the U.S. government for military applications, and an intentional degradation of the positioning accuracy, called Selective Availability, was installed to prevent nonmilitary receivers from attaining high accuracies. Selective Availability has since been deactivated, allowing commercial and recreational receivers to achieve higher accuracies, thus enabling the expansion of the GPS devices industry into the realm of location-based services (LBS), which are discussed later in this entry.

Global Positioning System

The Global Positioning System (GPS) is and how it is used. This unit will cover the basics of GPS and will highlight how GPS has changed our environment. This will work through the online study guide, complete class assignments, and take a short quiz at the end of the unit.

What is Global Positioning System?

The Global Positioning system is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS was originally intended for military applications, but in the 1980s, the government made the system available for civilian use. GPS works in any weather conditions, anywhere in the world, 24/7.

How does it work?

The global positioning system (GPS) is a satellite-based navigation system designed and operated by the U.S. Department of Defense (DoD). GPS can provide three-dimensional (3D) position and guidance in any weather and at any time of the day over the entire surface of the Earth, in the air, and in low space orbits. GPS consists of a control segment run by DoD, a space segment consisting of 24 or more satellites, and a user segment that includes military and civilian receivers (Ian, 2007, 56-89).

GPS evolved from earlier regional and global radio navigation systems such as the Navy Transit System, Omega, and Loran-C. It was first described in the mid 1970s, and by 1985, there were enough satellites to allow development and testing of receivers for land, sea, and air navigation and guidance as well as for time and frequency dissemination and for both geodetic and plane surveying. The system was declared operational in 1995.

DGPS is the basis for a wide variety of GPS approaches. Real-time, code-phase DGPS can make use of range corrections transmitted from ground-based or communications satellite radio transmitters. These real-time DGPS systems can provide 1-m accuracies when the receiver is within a few hundred kilometers of a DGPS reference station. Other systems such as the U.S. Federal Aviation Administration Wide Area Augmentation System provide corrections based on models for signal biases computed from a network of monitor receivers. These network solutions can result in 3-m accuracies anywhere within the national airspace service area of the system.

DGPS post processing can be accomplished if both remote and reference receivers store sufficient ...