Page 136 - Electrical Engineering Dictionary

circuit-set aclosedpathwhereallvertices register buffer. There is overlap between the
are of degree 2, thus having no endpoints in groups of adjoining registers that are accessi-
the path. ble when switching occurs. The overlapping
registers can be used for passing arguments
circuit-switched service a telecommu- during subroutine calls and returns. The cir-
nications service, where the communications cular register buffer is a feature of the SPARC
resource is retained for the whole period of CPU architecture. In the SPARC CPU there
communication. For example wired tele- are 256 registers, available 32 at a time, with
phone services or mobile telephone services an overlap of eight registers above and eight
in the first- and second-generation systems registers below the current group.
can be classified to circuit-switched services.
circular self-test path a BIST technique
circulant matrix a square N × N based on pseudorandom testing assured by
matrix M ={m i,j } such that m i,j = arranging flip-flops of a circuit (during test)
m ; that is, that each
(i+n)modN,(j+n)modN in a circular register in which each flip-flop
row of M equals the previous row rotated output is ex-ored with some circuit signal
one element to the right. All circulant matri- and feeds the input of the subsequent flip-
ces are diagonalized by the discrete Fourier flop. This register simultaneously provides
transform. test pattern generation and test result com-
paction.
circular cavity a section of the circular
waveguide closed at both ends by conducting circularity measure the size invariant ra-
plates.
tio of area divided by perimeter squared for
small shapes and much used as a preliminary
circularconvolution Seeperiodicconvolu-
discriminant or measure of shape, so-called
tion.
because it is a maximum for circular objects.
circular mil the area of a circle which
circularly polarized light light com-
measures 0.001 inch in diameter.
posed of two orthogonal polarizations that
Used to specify the cross-sectional area of
are 90 degrees out of phase; the resultant light
a wire.
amplitude vector thus rotates about the direc-
tion of propagation at the optical frequency.
circular polarization a polarization state
of a radiated electromagnetic field in which
circulator a multiport nonreciprocal de-
the tip of the electric field vector traces a
vice that has the property that an electromag-
circle as a function of time for a fixed po-
netic wave incident in port 1 is coupled to port
sition. The sense of rotation of the electric
2 only, an electromagnetic wave incident in
field vector is either right-hand or left-hand
port 2 is coupled into port 3 only and so on.
(clockwise or counter-clockwise).
circular register buffer a set of general CIRF See cochannel interference reduc-
purpose CPU registers organized to provide tion factor.
a large number of registers, which may be ac-
cessed a few at a time. The group of registers CISC processor See complex instruction
accessible at any particular time may be read- set computer.
ily changed by incrementing or decrementing
a pointer, with wraparound occurring from Citizen’s band (cb) 40 channels where
the highest numbered registers to the lowest the carrier frequency is between 26.965 MHz
numbered registers, hence the name circular and 27.405 MHz established by the FCC for

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2000 by CRC Press LLC