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Acronym or Abbreviation
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Term
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1XRTT
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One Times Radio Transmission Technology. Cellular data aka CDMA2000.
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802.11a
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54Mbps WLAN utilizing 5GHz carrier. Used mostly for campus networking.
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802.11b
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11Mbps WLAN utilizing 2.4GHz carrier. See also WiFi
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802.11g
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54Mbps WLAN utilizing 2.4GHz carrier.
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ADA
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Americans with Disabilities Act
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AFC
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Automatic Fare Collection
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AMT
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Automatic Message Trigger
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ANSI
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American National Standards Institute
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APC
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Automatic Passenger Counting
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APTA
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American Public Transportation Association
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ASA
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Automated Stop Announcement
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ASIC
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Application-Specific Integrated Circuit
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ASIS
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American Society for Industrial Security
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AVAS
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Automatic Voice Announcement System (see also DVAS)
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AVL
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Automatic Vehicle Location
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AVM
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Automatic Vehicle Monitoring
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BRT
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Bus Rapid Transit
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CAD
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Computer Aided Dispatch
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CAD/AVL
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Computer Aided Dispatch / Automatic Vehicle Location
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CDMA
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Code Division Multiple Access. Technique for allowing multiple devices (particularly wireless devices) to communicate over a shared network.
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CDPD
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Cellular Digital Packet Data (obsolete cellular data protocol)
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CF
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Compact Flash
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CPC
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Circular Plastic Connector
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CPU
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Central Processing Unit
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CRS
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Central Recording Station
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DHCP
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Dynamic Host Configuration Protocol. A protocol for automating the configuration of computers that use IP networks.
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DNC
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Data Network Controller. Computer and/or software which manages communications over a private radio network.
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DOD
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Department of Defense. Operates the GPS satellite constellation.
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DOT
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Department of Transportation
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DR
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Digital Recorders®
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DR (or D/R)
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Dead Reckoning. Using known speed, heading, and elapsed time to estimate a new position based on a previously determined position. Allows continued navigation when GPS reception is impaired.
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DRI
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DRI Corporation. Parent company of Digital Recorders, Inc., TwinVision na, Inc. and Mobitec Group
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DRSIP
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Digital Recorders® Simple Interface Protocol. A packet-based communications scheme which allows third party VLUs to control the operation of a DR500C+® or DR600® AVAS system.
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DSP
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Digital Signal Processing / Processor
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DVAS
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Digital Voice Announcement System (equivalent to AVAS)
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DVR
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Digital Video Recorder
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ECM
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Engine Control Module. Microcomputer system attached to vehicle engine which reports various parameters and status over the J1708 and/or J1939 networks.
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ECU
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Electronic Control Unit. Embedded system that controls one or more systems or subsystems in a vehicle and is typically a node on the vehicle network.
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EDSS
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Electronic Destination Sign Systems
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EISS
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Electronic Information Sign Systems
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ELYSÉ®
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Editing software for TwinVision Electronic Destination Sign Systems
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EVDO
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Evolution Data Only, or Evolution Data Optimized. Cellular data / successor to 1xRTT.
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FHSS
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Frequency Hopping Spread Spectrum. A technique for wireless communications.
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FTA
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Federal Transportation Administration
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GLONASS
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Global (Orbiting) Navigation Satellite System. Russian alternative to GPS
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GPRS
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General Packet Radio Service. A type of cellular data service (used by Digital Recorders® for AVL/PAS products).
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GPS
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Global Positioning System
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GSA
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General Services Administration
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GSM
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Global System for Mobile Communications. (Originally Groupe Spécial Mobile.) Cellular communications standards.
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IDEN
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Integrated Digital Enhanced Network (Motorola® variant of TDMA wireless)
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IDS
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Internal Display Sign
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IEEE
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Institute of Electrical and Electronic Engineers
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IP
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Internet Protocol. The network address for devices on IP networks is referred to as its “IP Address.”
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ISO
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International Organization for Standardization
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ITS
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Intelligent Transportation System(s)
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J1587
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Heavy Vehicle Data Interchange
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J1708
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Vehicle Area Network
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J1939
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CANbus for vehicles
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J2496
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Connector/cable system for J1708/J1939
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LAN
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Local Area Network
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LCD
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Liquid-Crystal Display
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LED
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Light-Emitting Diode
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LRV
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Light-Rail Vehicles
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MAC
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Media Access Control. The hardware address for an Ethernet device is a unique number (administered by the IEEE) and is referred to as the “MAC Address”
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MDT
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Mobile Display Terminal. Used somewhat interchangeably with OCU
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NOC
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Network Operations Center. Centralized location for AVL and other servers. The NOC has redundant high-speed data connections
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NMEA
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National Marine Electronics Association (publishes protocol for GPS communications)
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OCU
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Operator Control Unit. See also MDT.
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OEM
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Original Equipment Manufacturer
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OTvia®
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On Time Vehicle Information Access
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PASS
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Passenger Advisory Sign System. Includes shelter and transit center signs.
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PCMCIA
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PC Card
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PTT
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Push To Talk
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PRTT
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Priority Request To Talk
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RGB
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Red, Green, Blue
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RMM
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Route Mapping Module. Digital Recorders® product for managing geocoding of AVAS.
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RPSMA
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Reverse Polarity SMA – coaxial (RF) connection typically used for WLAN antennas
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RTB
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Run Time Bootable
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RTT
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Request To Talk
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SA
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Schedule Adherence
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SAE
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Society of Automotive Engineers
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SAM
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Schedule Adherence Module/Message
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SMA
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Sub-Miniature Version A. Coaxial (RF) connector, typically used for cellular antenna connections. See also RPSMA
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SMB
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Sub-Miniature Version B. Coaxial (RF) connector, typically used for GPS connections.
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TA
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Transit Authority
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TBUS
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NASDAQ® symbol for DRI Corporation Common Stock
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TCIP
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Transit Communication Interface Profiles
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TCM
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Transmission Control Module. Computer that controls vehicle transmission and communicates via J1708 and/or J1939 to the VLU.
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TCP
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Transport Control Protocol
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TCP/IP
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Transport Control Protocol / Internet Protocol
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TDMA
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Time Division / Multiple Access
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TFT
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Thin Film Transistor. Type of LCD display.
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TGM
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Trainline Gateway Module. Digital Recorder®s hardware/firmware product that extends J1708 communications over a train-lined wire pair.
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TSP
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Traffic Signal Preemption. System for extending green light or shortening red light for public vehicles (emergency and mass transit).
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TVna
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TwinVision na, Inc.
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TVS
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Transient Voltage Suppression (or Suppressor)
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UDP
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User/Universal Datagram Protocol. An alternative to TCP/IP that does not guarantee ordering or reliable delivery.
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UITP
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International Association of Public Transport
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USB
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Universal Serial Bus
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VAN
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Vehicle Area Network (usually J1708 or J1939)
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VLU
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Vehicle Logic Unit. DR500C+® or DR600®
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VMS
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Variable Message Sign. Generic term for electronic sign that can display any number of messages.
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VOIP
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Voice Over Internet Protocol
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VPN
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Virtual Private Network
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WAAS
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Wide Area Augmentation System. A system of satellites and ground stations which provide suitably equipped GPS receivers to compensate for atmospheric conditions.
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WAN
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Wide Area Network
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WiFi
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Wireless Fidelity. IEEE 802.11b WLAN (also refers to 802.11g).
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WLAN
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Wireless Local Area Network. Usually refers to IEEE 802.11x.
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