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SIG-00-07-11 SEPTEMBER 2012 (REVISED OCTOBER 2019)
Version No.: B.2
GLOSSARY
TERM
DESCRIPTION
AAR
Association of American Railroads – An organization that establishes uniformity and
standardization among different railroad systems.
ACSES
Advanced Civil Speed Enforcement System – A Vital Interface Unit that provides
functions according to Wayside Interface Unit (WIU) requirements as defined by the
Association of America Railroads (AAR). It also provides functions according to
ACSES Encoder requirements. Its dual function capability allows an ACSES train and
a train that is capable of interfacing with a WIU to obtain wayside vital information.
Aspect
(Signal Aspect) The appearance of a fixed signal conveying an indication as viewed
from the direction of an approaching train. A cab signal conveying an indication as
viewed by an observer in the cab.
ATCS
Advanced Train Control System – A set of standards compiled by the AAR for
controlling all aspects of train operation.
BCP
Base Communication Packet, or Base Station
CBTC
Communications Based Train Control. An automated control system for railways that
ensures the safe operation of rail vehicles using data communication between various
control entities that make up the system.
CETC
Centralized Electrification & Train Control
CDMA
Code Division Multiple Access. This is a form of spread spectrum signaling using
different codes on one or more channels.
Checksum
A simple way to protect the integrity of data by detecting errors in data that are sent
through space (telecommunications) or time (storage). It works by adding up the basic
components of a message, typically the asserted bits, and storing the resulting value.
Anyone can later perform the same operation on the data, compare the result to the
authentic checksum, and (assuming that the sums match) conclude that the message
was most likely not corrupted.
Configuration
File
When changes are made to the default settings in the MCF (Master Configuration
File), the custom settings are maintained in the configuration file.
CRC
Cyclic Redundancy Check. A type of function that takes an input of data stream of
any length and produces as output a value of a certain fixed size. The term CRC is
often used to denote either the function or the function's output. A CRC can be used
as a checksum to detect alteration of data during transmission or storage. CRCs are
particularly good at detecting common errors caused by noise in transmission
channels.
CTV
Television Compatibility Box
DSU
Data Service Unit