InterReach Unison Installation, Operation, and Reference Manual
D-3
D-620003-0-20 Rev J
CONFIDENTIAL
Circuit
A communication connection between two or more points. A circuit can
transmit either voice or data.
CO
Central Office. The main switching facility for a telecommunications system.
CTIA
Cellular Telecommunications Industry Association. The CTIA is an industry
association made up of most of the wireless carriers and other industry players. It
was formed in 1984 to promote the cellular industry and cellular technology.
D-AMPS
Digital Advanced Mobile Phone Service. See IS-54.
dB
Decibel. A unit for expressing the ratio of two amounts of power. It is often used
in wireless to describe the amount of power loss in a system (i.e., the ratio of
transmitted power to received power).
DCS
Digital Communications System. DCS is often called “upbanded GSM” since
it is the GSM access scheme adopted to operate in the 1700–1800 MHz portion
of the spectrum.
Digital
A method of storing, processing, and transmitting information by represent-
ing information as “0s” and “1s” via electrical pulses. Digital systems have
largely replaced analog systems because they can carry more data at higher speed
than analog transmission systems.
Electromagnetic Spectrum
Electrical wave forms in frequency ranges as low as
535 kHz (AM radio) and as high as 29 GHz (cable TV).
ESMR
Enhanced Specialized Mobile Radio. Digital mobile telephone services
offered to the public over channels previously used for two-way analog dispatch
services. ESMR provides digital mobile radio and telephone service as well as
messaging and dispatch features.
ETSI
European Telecommunications Standards Institute. ETSI was established in
1988 to set standards for Europe in telecommunications, broadcasting and office
information technology.
FCC
Federal Communications Commission. In the United States, the FCC is
responsible for the management and regulation of communication policy for all
public communications services, including wireless.
FDMA
Frequency Division Multiple Access. A wireless access protocol that
assigns each user a specific radio channel for use. Since FDMA only supports
one user (or conversation) on each channel, it does not maximize use of the spec-
trum and is therefore largely been superseded by other access protocols (such as
CDMA, TDMA, GSM, iDEN) that support multiple users on a single channel.
Frequency Hopping
A wireless signal transmission technique whereby the fre-
quency used to carry a signal is periodically changed, according to a predeter-
mined code, to another frequency.
