ciation (TIA) for a digital cellular communi-
cation system. One of a set of digital cellular
systems commonly classified as second gen-
eration cellular systems. A standard origi-
nally designed to succeed the AMPS cellu-
lar standard. This interim standard has now
been finalized in the standard known as IS-
136. The standard is based on the use of the
same channel structure as the AMPS stan-
dard (30 kHz channels), similar frequency
reuse and concept of hand-off, but with the
use of a digital modulation scheme, known
as
π/4-shifted DQPSK, to transmit a digital
signal at the rate of approximately 47 kbps
on a 30 kHz channel. This signal typically
carries three digital voice signals encoded at
the rates of 8 kbps, excluding additional over-
head bits that are used for the purpose of error
correction.
IS-95
an interim standard of the U.S.-
based Telecommunications Industries Asso-
ciation (TIA) for digital cellular communi-
cation systems.
One of a set of systems
commonly classified as second-generation
cellular systems.
The standard is based
on spread spectrum modulation employing
CDMA. This standard makes use of the con-
cepts of power control, soft hand-offs, pi-
lot signals, pilot phase offsets, orthogonal
CDMA, and Walsh functions.
ISDN
See
integrated services digital
network
.
ISEF
See
infinite symmetric exponential
filter
.
ISI
See
intersymbol interference
.
ISMA
See
inhibit sense multiple access
protocol
.
ISO
(1) International Standards Organi-
zation.
(2) Independent System Operator, an en-
tity created to operate power generation and
transmission systems but which does not own
these facilities.
iso-dense print bias
the difference be-
tween the dimensions of an isolated line and
a dense line (a line inside an array of equal
lines and spaces) holding all other parameters
constant.
isodata
a special elaboration of K-means
used for clustering.
isofocal bias
the difference between the
desired resist feature width and the isofocal
linewidth.
isofocal linewidth
the resist feature width
(for a given mask width) that exhibits the
maximum depth of focus.
isokeraunic map
a map which denotes the
variation of lightning activity over an area by
making use of observations of the incidence
of thunder.
isolated
a power electronic circuit that has
ohmic isolation between the input source and
the load circuit.
isolated buck-boost converter
See
flyback
converter
.
isolated I/O
an I/O system that is elec-
trically isolated from where it is linked to.
Isolated I/O is often found in embedded sys-
tems used for control.
isolation
(1) the separation of a part from
other parts of the system so that the effects of
undesired changes in the system are not seen
by the separated part.
(2) a figure (usually expressed in decibels)
to describe how well a transmitting device
(source) and receiving device (receiver) are
separated electrically; the amount of (usually
undesirable) signal appearing at the receiver
from the transmitting source from an undesir-
able signal path such as leakage in a coupler,
mutual coupling, or multipath.
isolation switch
See
bypass switch
.
c
2000 by CRC Press LLC