| Automatic Vehicle Locator
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Definition
Automatic vehicle location (AVL) is a
computer -based vehicle tracking system. For transit, the actual real
-time position of each vehicle is determined and relayed to a control
center. Actual position determination and relay techniques vary,
depending on the needs of the transit system and the technologies
employed. Transit agencies often incorporate other advanced system
features in conjunction with AVL system implementation. Simple AVL
systems include: computer -aided dispatch software, mobile data
terminals, emergency alarms, and digital communications.
More sophist
icated AVL Systems may integrate: real-time passenger information,
automatic passenger counters, and automated fare payment systems. Other
components that may be integrated with AVL systems include automatic
stop annunciation, automated destination signs, Vehicle component
monitoring, and Traffic signal priority. AVL technology allows improved
schedule adherence and timed transfers, more accessible passenger
information, increased availability of data for transit management and
planning, efficiency/productivity improvements in transit services .
What is AVL technology?
Automated Vehicle Locator (AVL) systems use
satellite and land communications to display each vehicle's location,
status, heading, and speed on the computer's screen. AVL systems use
one of four types of navigation technology, or may combine two of these
technologies to compensate for inevitable shortcomings of any one
technology. The four principal technologies employed for AVL systems
are: 1. Global Positioning System
2. Dead-Reckoning System
3. Signpost/Odometer Systems 4. Radio Navigation/Location
TRACKING SYSTEMS
PASSIVE TRACKING:
The Passive Tracking System modality refers to stand
-alone GPS Receivers, which store data for further process. Passive
systems are typically limited to vehicle tracking only. When a Passive
Tracking Device is installed in a vehicle, the location, time, velocity
and heading data is usually stored in the unit or transferred to a
handheld device and downloaded from the vehicle when the vehicle
returns to their base station.
REAL TIME TRACKING
Real Time
Tracking Systems are based on mobile stand-alone terminals which
combine GPS and GSM technology to determinate and transmit their
position. A two-way wireless communication link connects the unit with
the control center at all times. A portable GPS tracking device can be
used as an emergency cellular phone with speed dialing for two -way
voice communication. It can silently call any emergency number in the
world for immediate assistance. The emergency silent call feature also
provides a digitized voice message which can report the time, date,
speed, heading, and location of a person in distress .
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