18WuD2x

synchronous computer • synthesizer 669
synchronous computer A computer whose operations
are timed by single-frequency clock signals.
synchronous contacts The rectifying contacts of a
synchronous vibrator (see VIBRATOR-TYPE REC-
TIFIER).
synchronous converter A synchronous machine
that can run on alternating current and generate
direct current, or vice versa. Also called ROTARY
CONVERTER.
synchronous gate A gate whose output is synchronized,
according to the input signal.
synchronous generator An alternator operating in
synchronism with one or more other alternators.
Also see SYNCHROSCOPE, 2.
synchronous induction motor An alternatingcurrent
motor that is intermediate between the
fractional-horsepower reluctance motor and the
multiple-horsepower three-phase, synchronous
motor. The synchronous induction machine
starts like an induction motor and runs like a
synchronous motor.
synchronous inputs In a computer flip-flop, inputs
that accept pulses only at the command of
the clock.
synchronous machine See SYNCHRONOUS IN-
DUCTION MOTOR.
synchronous motor See SYNCHRONOUS INDUC-
TION MOTOR.
synchronous network A communications network
in which all clocks are set so that they run at the
same rate, their increments are identical in duration,
and transitions occur simultaneously or
with a specified phase difference. Such a system
allows for greatly enhanced signal-to-noise ratio
for a given amount of transmitter power, and also
reduces the bandwidth necessary for a single signal
so that many more signals can be placed in a
given frequency band.
synchronous orbit See GEOSTATIONARY ORBIT.
synchronous satellite See GEOSTATIONARY
SATELLITE.
synchronous speed For an alternating-current
(ac) machine, the speed corresponding to the ac
frequency.
synchronous transmission A method of signal
transmission in which individual symbols are
sent at a specified rate, according to a clock that
also governs the receiver.
synchronous vibrator See VIBRATOR-TYPE REC-
TIFIER.
synchroscope 1. An oscilloscope having a highspeed
sweep triggered by a synchronizing signal.
Such an instrument is valuable for viewing highspeed
pulses. 2. A pointer-type instrument used
to indicate the synchronism between two power
alternators.
synchro system A circuit or system using synchros
for the transmission and reception of positioning
signals. Also see SYNCHRO.
synchrotron A particle accelerator that uses a
high-frequency electrostatic field and a low-
Collector
synchrotron
Linear
accelerator
Circular
accelerating
chamber
frequency magnetic field to impart very high
velocity to the particles.
sync pulse 1. A pulse used to control the frequency
or repetition rate of an oscillator or other
generator. 2. In a television system, a pulse
transmitted as part of the composite video signal
to control scanning. Also see HORIZONTAL SYNC
PULSE and VERTICAL SYNC PULSE.
sync separator In a television receiver circuit, a
stage used to separate and deliver the sync
pulses from the composite video signal. See, for
example, DIODE SYNC SEPARATOR.
sync signal See SYNCHRONIZING SIGNAL.
sync takeoff The point in the video amplifier circuit
of a television receiver at which the composite
video signal is sampled to extract the sync
pulses.
syntax 1. The rules by which computer program
statements are structured. 2. The way that a
written or spoken sentence is constructed. It is
important in speech recognition and speech synthesis.
synthesis The rigorous (usually mathematical) design
of an electronic circuit or device and the accurate
prediction of its performance. Compare
ANALYSIS.
synthesizer 1. See SIGNAL SYNTHESIZER. 2. A
circuit synthesizer (i.e., a device that allows a
wide variety of circuits to be set up temporarily or
simulated, for testing and evaluating). Sometimes,
a specially programmed computer serves
this purpose. 3. A keyboard on which music can
be played, and whose output can be adjusted to
simulate the sounds of various musical instruments.
4. See MOOG SYNTHESIZER.