18WuD2x

signal rectifier • silicon capacitor 629
RF
In
signal rectification
dc
Out
signal rectifier See SIGNAL DIODE.
signal regeneration See SIGNAL RESHAPING.
signal reshaping 1. The processing of a signal so
that it acquires its original waveform. Also called
signal regeneration. 2. Passing a digital signal of
any type through a circuit that delivers a uniform
output pulse on a real-time one-to-one
basis.
signal shifter 1. A device used for quickly changing
the frequency of a transmitted signal. 2. A device
that automatically causes a transmitted
signal to be sent on a frequency that differs from
the receiver frequency by a known and predetermined
amount. 3. See MIXER, 1. 4. See CON-
VERTER, 1.
signal squirter See SIGNAL INJECTOR.
signal strength The amplitude of a signal, usually
in terms of voltage. Current or power is specified
in some applications.
signal-strength meter 1. See FIELD-STRENGTH
METER. 2. See S-METER.
signal synthesizer A special signal generator delivering
signals whose frequency, amplitude, and
waveshape can be adjusted at will.
signal time delay The time required for an element
of a signal to be transmitted through a circuit or
network. This delay results in phase shift in an
amplifier.
signal-to-distortion ratio In a receiver, the ratio of
the desired signal to the level of distortion other
than the specified signal. Usually expressed in
decibels (dB).
signal-to-image ratio Abbreviation, S/I. In a receiver,
the ratio of signal amplitude to image amplitude,
both being measured in the same units.
It is usually expressed in decibels (dB).
signal-to-noise-plus-noise ratio Abbreviation,
(S+N)/N. In a receiver, the ratio of the combined
signal and noise amplitude to the amplitude of
the noise alone. It is usually expressed in decibels
(dB). Peak voltages are used to determine this ratio
in the case of pulse noise; root-mean-square
(rms) voltages are used in the case of random
noise.
signal-to-noise ratio Abbreviations: S/N, SNR. In
a receiver, the ratio of signal amplitude to noise
amplitude. It is usually expressed in decibels
+
(dB). Peak voltages are used to determine this ratio
in the case of pulse noise; root-mean-square
(rms) voltages are used in the case of random
noise.
signal-to-noise-and-distortion ratio Abbreviation,
SINAD. In a receiver, the ratio of the desired
signal to the level of noise and distortion, other
than the specified signal. It is usually expressed
in decibels (dB).
signal tracer A tuned or untuned detector/amplifier
having an input probe and an output indicator
(meter, loudspeaker, or both), for following a
test signal through a circuit.
signal voltage The voltage component of a signal,
as opposed to the operating voltage of the circuit
generating or passing the signal.
signal wave 1. Any electromagnetic disturbance of
a periodic nature that is modulated to convey information.
2. The visual illustration or rendition
of an electromagnetic disturbance that is modulated
to convey information.
signal winding In a magnetic amplifier or saturable
reactor, the coil that receives the control
current.
signal window See WINDOW, 2.
signal wobbulator A frequency modulator used
with an unmodulated signal generator to provide
sweep signals for visual alignment. Also see
WOBBULATOR.
sign bit A one-bit SIGN DIGIT.
sign digit A character indicating the sign (positive
or negative) of the value of the field or word to
which it is attached (usually at the end).
signed field In a computer record, a field having a
number whose sign is indicated by a SIGN DIGIT.
significant digits See SIGNIFICANT FIGURES.
significant figures In a numerical quantity, especially
one expressed in scientific (power of 10) notation,
those figures (digits) that depict a quantity
to a required, relevant, or justifiable degree
of precision. For example, 173,201 expressed
to three significant figures is 1.73 × 10 5 ;
0.00477583 expressed to four significant figures
is 4.776 × 10 –3 . See also SCIENTIFIC NOTATION.
silencer See AUTOMATIC NOISE LIMITER.
silent alarm In security systems, the transmission
of a warning signal to attendant human operators
and/or computers, without producing an audible
or visible warning to intruders.
silent alignment See VISUAL ALIGNMENT.
silent piano See ELECTRONIC PIANO.
silica pencil A rod of silicon dioxide heated to emit
infrared rays.
silicon Symbol, Si. A metalloidal element. Atomic
number, 14. Atomic weight, 28.086. Silicon is
abundant in the earth’s crust. It is used in many
semiconductor devices, including integrated circuits,
diodes, photocells, rectifiers, and transistors.
silicon capacitor
PACITOR.
See VOLTAGE-VARIABLE CA-