Page 139 - Electrical Engineering Dictionary

load impedance optimized not only for a fun- sifier with differentiating capability between
damental wave but also for harmonic waves the types of features. A number of codebooks
to improve efficiency. An efficiency of the are developed each to encode blocks of pix-
class F amplifier is 100% under an ideal con- els containing specific types of features. See
dition, where the optimum load impedance also vector quantization.
for even harmonic waves is short and that for
odd harmonic waves is open. classifier (1) given a set of patterns of
different classes, a classifier is a system ca-
class G amplifier a frequency multiply- pable of determining the membership of each
ing or harmonic amplifier biased somewhere pattern.
between class A and class C, in which the (2) a method of assigning an object to one
input is tuned to the fundamental input fre- of a number of predetermined classes.
quency and the output is tuned to a frequency
multiple of the input. clean cache block a cache block (or
“line”) is clean if it is a copy of the informa-
class H amplifier frequency mixing am- tion stored in memory. A clean block can be
plifier biased somewhere between class A overwritten with another block without any
and class C, in which the inputs are tuned to need to save its state in memory.
the input frequencies and the output is tuned
to either the sum or difference frequency. clear (1) to set the value of a storage
location to zero (often used in the context of
class S amplifier sampling or pulse width flip-flops or latches).
modulation amplifier in which a sampling (2) clearing a bit (register) means writing
circuit (or pulse width modulator), pulse am- a zero in a bit (register) location. Opposite to
plifier and a low pass filter are cascaded. “set.”
The input signal is sampled at a significantly
higher rate than the input frequency (this re- clearing time the total time required to
quires a high frequency sampling signal), melt and clear, and thus totally open, a fuse-
and the original signal is transformed into type overcurrent device.
a constant amplitude pulse chain in which
the pulse widths are proportional to the orig- cleaved coupled cavity semiconductor
inal signal’s amplitude. The resulting pulse laser configuration in which the amplifying
chain is amplified using any of the highly effi- region has been cleaved to introduce a mid-
cient switching methods desired. The output cavity reflecting boundary; added reflector is
is then demodulated using a low pass filter, intended to improve mode-selectivity char-
replicating the original signal. It is impor- acteristics.
tant to note that rapid variations in the input
signal amplitude relative to the sampling sig- click noise in a fading channel, the noise
nal will cause significant distortion or loss of associated with a threshold crossing. In a
information. fading radio channel situation, the moving
user crosses the standing wave patterns in
classified VQ See classified vector the propagation environment. As the user
quantization. crosses the minima, the service quality tem-
porarily downgrades and, in analogue sys-
classified vector quantization (CVQ) tems, is noticeable as clicking.
a vector quantization technique where dif-
ferent codebooks are developed based image climbers two metal spikes, each of which
edge features. The codebook used to encode is strapped to the inside of a line worker’s
a particular block is determined by a clas- legs, pointing down near the ankle. Plunged

c
2000 by CRC Press LLC