Terminology Used in this Guide
The following table explains some of the terms that are used in this guide.
| Term | Definition |
|---|---|
| GPS | Global positioning system |
| AVL | Automatic vehicle location |
| MDT |
Mobile data terminal. Also known as an MDC— mobile data computer. The term MDT (Mobile Data Terminal) is a mobile technology term, which generally refers to a "dumb terminal" type of computer hardware installed on a transit vehicle. For purposes of this guide, the term "mobile computer" is used since it applies to both legacy models as well as Windows-based models of mobile hardware. |
| Capacity | The limit of events that can be shown on a driver’s manifest. |
| Critical Capacity | The maximum number of events an MDT is programmed to receive (at which point it cannot receive any additional trips or insertions). |
| Event | An activity that can be scheduled on a driver’s manifest such as a pick-up, drop-off, pull-in, pull-out, or driver break. This term is preferred over the use of “stop”. |
| Manifest | The itinerary for a driver or vehicle, also known as an itinerary, or the driver’s work. |
AVL
Automatic Vehicle Location (AVL) is a method used for determining the location of a vehicle on the earth’s latitude and longitude coordinates.
The most common means of determining AVL is by data received from the Global Positional System (GPS). Other methods for determining location are dead reckoning, inertial navigation, or Radio Frequency Identification (RFID) readers; sometimes a combination of these methods can be used.
GPS
The Global Positioning System (GPS) is a constellation of satellites that orbit the earth twice a day, transmitting exact time and position (latitude, longitude and altitude) information. With a GPS receiver, users such as paratransit sites can determine the location of their vehicles anywhere on earth.
The heart of GPS technology is exact time and position information. Using atomic clocks and location data, each satellite continuously broadcasts the time and its position. A GPS receiver receives these signals, listening to three or more satellites at once, to determine the users’ positions on earth.
Both AVL and GPS provide information on the location of the vehicles to the Dispatch center.