Article Global Positioning Systems

Last modified: December 29, 2007

GLOBAL POSITIONING SYSTEMS


The Global Positioning System (GPS) is a worldwide radio wave navigation system formed from a constellation of 24 satellites and their ground stations to determine accurate location and time. It was developed by the U.S. Department of Defense with the primary purpose of enhancing the effectiveness of U.S. and allied military forces. GPS is rapidly becoming an integral component of the emerging Global Information Infrastructure, with applications ranging from mapping and surveying to international air traffic management and global change research.

These days people from different walks of life are using GPS in ways that make their work more productive, safer, and sometimes even easier.


The real-world applications of GPS fall into five broad categories:

Location

The first application of GPS is the determination of a "position" or location. GPS is the first positioning system to offer highly precise location data for any point on the planet, in any weather.

Navigation

Navigation is the process of getting something from one location to another. GPS helps to determine exactly where we are, but sometimes important to know how to get somewhere else. It was originally designed to provide navigation information for ships and planes.

Tracking

Tracking is the process of monitoring the movement of people and things as it moves along. GPS used in effective fleet management.

Mapping

Mapping means creating maps of the world. It is a big world out there, and using GPS to survey and map it precisely saves time and money.

Timing

GPS used to disseminate precise time, time intervals, and frequency. It makes the job of "synchronizing our watches" easy and reliable.

GPS receivers integrate a radio and a navigation computer and can receive the faint, twenty-watt signals coming from the satellites. The computer uses these signals to calculate the distance between the satellites and the receiver. With this information, the computer can further calculate the position and velocity of the receiver.

The number of satellites visible to a receiver constantly varies between four and eleven according to time and location. Each satellite broadcasts a number of unique spread-spectrum codes, but only one, the Coarse Acquisition (C/A) code, is easily accessible for civilian use. Code is effectively a timing signal synchronized to an international time standard-Universal Coordinated Time (UCT).

GPS


DGPS (Differential GPS)

Basic GPS is the most accurate radio-based navigation system ever developed. And for many applications it's plenty accurate. But it's human nature to want MORE! Differential GPS is a way to correct the various inaccuracies in the GPS system and pushing its accuracy even farther.
DGPS uses correction signals from one of four (4) sources for improving accuracy:

Coast Guard Beacon

Coast Guard Beacon Correction is a signal based off towers set-up. These towers act as both the reference location and the transmission site. A benefit of this type of transmission is its ability to follow the contour of the ground better than higher frequency signals. However, this can allow bad weather, such as thunderstorms, to affect performance of the system.

WAAS (Wide Area Augmentation System)

WAAS, formally called the Wide Area Augmentation System, is a correction source designed for the FAA (Federal Aviation Administration). "Augmented GPS" uses a geostationary satellite as a relay station for the broadcast of corrections. This tool has been put in place to assist aircraft positioning.

Omnistar

Omnistar is a privately held company that provides subscriptions for GPS correction. A user would select which zone he is operating in and Omnistar provides the corrections accordingly. A new correction source called Omnistar HP is a newer signal and provides customers with a higher level of accuracy (decimeter).

RTK (Real Time Kinematics)

Real Time Kinematics corrections are achieved by using a local base station that contains both a GPS receiver for positioning and radio for transmitting to a mobile unit. This technology is a more advanced form of positioning that allows for activities such as steer assist products, elevation mapping, and surveying.

More can be found on:

http://www.beaglesoft.com/gpstechnology.htm
http://electronics.howstuffworks.com/gps.htm

GPS Simulator Installation & System Requirements
Operating System: Windows 9x, Windows XP, Windows 2000, Windows 2002, Windows 2003, Embedded XP
Installation: Download the setup.exe from our Vutog website (http://gps.vutog.com/download.html) and install it.