Common GPS Technology and Fleet Management Terms

Automatic Crash Notification (ACN) - vehicle onboard system designed to notify a designated call center in the event of a significant collision, reporting the vehicle location, speed and severity of the crash, deployment of airbag(s) and other diagnostic information from onboard sensors (sometimes referred to as "Mayday Systems"). An "Accelerometer" is often used to track the suddenness of the impact and activate notification when preset G-Force is achieved.

Automatic Vehicle Location (AVL) - the automated system and related technology of tracking vehicle locations. AVL systems utilize GPS technology coupled with wireless communication systems to provide a vast array of data to the home station and/or fleet operator.

Data Packet - Information about a vehicle or group of vehicles, or other non-voice data, transmitted via communication conduits (cellular, Internet, etc.) to the fleet management system computer.

Differential GPS - using data from at least four (4) GPS signals, this method of GPS corrects for a designed random error to achieve a more precise location, usually within 2 meters. This system utilizes a fourth location signal from land based signal towers maintained by the US Coast Guard to enhance the accuracy of GPS for navigation on the waterways.

Enhanced 911 (E-911) - based on a Federal Communications Commission (FCC) mandate, all cellular phones built after October 1, 2001 must be equipped to identify the caller's location at the 911 Call Center.

Galileo - essentially the European version of GPS, this system is currently under development. It will ultimately consist of 21 to 28 satellites in a mid-Earth orbit (MEO) and between 3 and 8 satellites in geosynchronous (GEO) orbit, which may use signals from GPS.

General Packet Radio System (GPRS) - packet switching technology where information is transmitted in short bursts of data over an IP-based network allows continuous connection to data networks in support of many kinds of applications, including messaging and rapid data transfer.

Geocoding - Using latitude and longitude data from the GPS receiver to determine the map location, and (with software) find the exact street address or block address.

Geographic Information Systems (GIS) - a combination of the geospatial data systems and software designed to support transportation routing and logistics, generally for a municipality or regional area.

Global Orbiting Navigation Satellite System (GLONASS) - a Russian space-based navigation system comparable to the American GPS system, GLONASS is comprised of 21 satellites in 3 orbital planes, with 3 on-orbit spares.

Global Positioning System (GPS) - A technology that uses signals and data from multiple satellites to determine a location anywhere on Earth.

Global System for Mobile Communications (GSM) - originally short for 'Groupe Spécial Mobile' GSM is the digital wireless communication standard for Europe, as well as South Africa, Australia, and many Middle and Far East countries. GSM has recently been introduced in the United States and is rapidly expanding throughout North America.

Intelligent Transportation Systems (ITS) - A general term for many technology systems used in highway, rail and other transit to improve mobility, reduce accidents, and improve transportation overall, i.e. electronic toll collection systems, synchronized traffic signals.

NAVSTAR - The Navstar Global Positioning System (GPS) is a space-based constellation of orbiting satellites providing navigation data to military and civilian users all over the world. This system is maintained by the U.S. Military and provides the foundation for almost all commercial GPS systems in use in the United States.

"Ping" - A vehicle status update request, available only with fleet management systems offering active/real-time vehicle location capability.

"Random Error Code" - This is a designed error for commercial GPS systems and was set up in 1982 when the U.S. Military was instructed by Congress to make GPS available for commercial use. The error is intended to prevent the Navistar System from being used accurately against the U.S. Military. In 2000 the error was reduced from 100 meters to approximately 9 meters. Differential GPS, maintained by the U.S. Coast Guard, corrects this intentionally designed random error.

Selective Availability - prior to May 2000, the US military intentionally degraded the accuracy of GPS signal data for civil and commercial purposes as a protective measure. The Department of Defense retains the right to restrict signal accuracy in the interest of US national defense.

Telematics - a general term referring to emerging technologies in automotive communications, combining wireless voice and data capability for management information and safety applications.