18WuD2x

562 pulsed laser • pulse-time modulation
pulsed laser A laser in which flashes (pulses) of
high-intensity light excite the lasing medium.
pulse duration The time period during which a
pulse exists (i.e., its width on an oscilloscope display).
pulse-duration modulation Abbreviation, PDM.
See PULSE WIDTH MODULATION.
pulse equalizer A MONOSTABLE MULTIVIBRA-
TOR adapted to deliver pulses of equal amplitude,
shape, and width—even when it receives trigger
pulses of different kinds.
pulse fall time The time required for the trailing
edge of a pulse to fall from 90 to 10 percent of its
peak amplitude. Compare PULSE RISE TIME.
pulse-forming line A circuit used in radar for producing
high-intensity pulses. Inductances and
capacitances are combined in a long string, and
the effect is to generate high-amplitude radiofrequency
pulses.
pulse-frequency modulation Abbreviation, PFM.
See PULSE-INTERVAL MODULATION.
pulse generator A signal generator that produces
pulses. A general-purpose generator of this sort
will produce pulses of adjustable amplitude, duration,
shape, and repetition rate.
pulse-height discriminator A circuit or device
that passes only pulses whose amplitudes exceed
a predetermined level.
pulse interval The interval between successive
pulses.
pulse-interval modulation Abbreviation, PIM.
Also called pulse-frequency modulation (PFM) or
pulse-numbers modulation (PNM). A method of
conveying information in wireless communications.
A train of pulses is transmitted. Every
pulse has the same amplitude and the same duration,
but their rate fluctuates with the modulating
waveform. When there is no modulation, the
pulses are evenly spaced with respect to time. An
increase in the instantaneous data amplitude
might cause pulses to be sent more often (positive
modulation) or less often (negative modulation).
pulse inverter A single-stage, wideband, lowdistortion,
common-emitter, or common-source
amplifier. The output-pulse waveforms are
therefore inverted, with respect to the input-pulse
waveforms.
pulse jitter In a pulse train, a disturbance characterized
by random changes in the spacing between
pulses.
pulse-length modulation See PULSE-DURATION
MODULATION.
pulse load The load impedance for a pulse generator.
pulse mode See PULSE MODULATION.
pulse modulation See PULSE-AMPLITUDE MOD-
ULATION, PULSE-CODE MODULATION, PULSE-
INTERVAL MODULATION, PULSE-POSITION
MODULATION, PULSE-WIDTH MODULATION.
pulse modulator 1. A modulator that delivers
power or voltage pulses for modulating a carrier.
2. A device that modulates pulses (see PULSE
MODULATION, 2).
pulse narrower A circuit or device that reduces the
duration (width) of a pulse.
pulse-numbers modulation Abbreviation, PNM.
See PULSE-INTERVAL MODULATION.
pulse operation Intermittent operation of a circuit,
in the form of discrete pulses.
pulse oscillator Any oscillator with an output that
consists of a series of pulses.
pulse-position modulation Abbreviation, PPM. A
method of conveying information in wireless communications.
A train of pulses is transmitted. The
timing of each individual pulse varies according
to the modulating waveform. The pulses
occur earlier or later than the nominal (zeromodulation)
time, depending on the instantaneous
amplitude of the modulating signal.
pulse rate See PULSE REPETITION RATE.
pulse ratio The ratio of pulse height (amplitude) to
pulse width (duration).
pulse regeneration Restoration of the original
waveform and frequency to a pulse. It eliminates
distortion caused by circuits or propagation conditions.
pulse repetition frequency Abbreviation, PRF.
See PULSE-REPETITION RATE.
pulse-repetition rate Abbreviation, PRR. The
number of pulses per unit time; usually pulses
per second (pps).
pulse rise time The time required for the leading
edge of a pulse to rise from 10 to 90 percent of its
maximum amplitude. Compare PULSE FALL
TIME.
pulse scaler A circuit actuated by the reception of
a definite, predetermined number of input
pulses.
pulse-shaping circuit 1. A circuit for producing a
pulse from a wave of some other shape (e.g., sine
wave). 2. A circuit for tailoring a pulse to desired
shape, amplitude, and duration.
pulse spacing The interval between successive
pulses.
pulse-spacing modulation Abbreviation, PSM. See
PULSE-INTERVAL MODULATION.
pulse-steering diode In a flip-flop circuit, a diode
through which the trigger pulse must pass to
switch the circuit. Because of the unidirectional
conductivity of a diode, pulses of only one polarity
are passed.
pulse stretcher 1. A shaping circuit that widens a
pulse (i.e., increases its duration). 2. A circuit,
such as a special monostable multivibrator, that
generates a pulse that is wider than the trigger
pulse.
pulse stuffing See JUSTIFICATION, 2.
pulse tilt The sloping of the normally flat top of a
pulse either up or down. Also see PULSE DROOP.
pulse time See PULSE DURATION.
pulse-time modulation See PULSE-POSITION
MODULATION.