18WuD2x

452 modes of propagation • modulation capability
modes of propagation The configurations in
which microwave energy can be transmitted
through a WAVEGUIDE.
modes of resonance In a microwave cavity, the
configurations in which resonant oscillation can
exist, depending on the way the cavity is excited.
modification 1. Changing the configuration of a
circuit, device, or system, usually to a minor extent,
to tailor its characteristics for a specific purpose.
2. Changing some aspect of a signal for a
specific purpose (e.g., reducing the emission
bandwidth to allow more signals to fit within a
given band of frequencies). 3. In computer operations,
changing program addresses and instructions
by performing logic and arithmetic on them,
as if they were data. Also see PROGRAM MODIFI-
CATION.
modified alternate mark inversion A signal that
is similar to alternate mark inversion (AMI), but
contains certain differences that are specified by
a rigorous set of standards for the particular signal.
modifier A data item used to change a computer
program instruction so that it can be used to implement
different successive operations. Also see
PROGRAM MODIFICATION.
modifier register See INDEX REGISTER.
modify To perform a MODIFICATION to a circuit,
device, system, signal, program address, etc.
moding A fault characterized by oscillation of a
MAGNETRON in undesirable modes.
modular technique See BUILDING-BLOCK TECH-
NIQUE.
modulated amplifier A usually high-frequency
amplifier whose output is varied in some way for
the purpose of conveying intelligence. Compare
MODULATED OSCILLATOR. In the amplitude
modulation of an amplifier, there is little or no
disturbance of the carrier frequency. Also see
MODULATION.
modulated beam 1. An electron beam (as in a
cathode-ray tube), whose intensity is varied by a
desired signal. 2. A light beam whose intensity is
varied for communications or control purposes.
modulated carrier A carrier wave whose amplitude,
frequency, or phase is varied to convey intelligence.
modulated continuous wave Abbreviation, mcw.
A high-frequency carrier wave modulated by a
continuous, lower-frequency wave, as in MCW
telegraphy.
modulated CW See MODULATED CONTINUOUS
WAVE.
modulated electron beam See MODULATED
BEAM, 1.
modulated light beam See MODULATED BEAM,
2.
modulated oscillator A usually high-frequency
oscillator whose output is varied in some way to
convey intelligence. Compare MODULATED AM-
PLIFIER. Also see MODULATION.
RF in
+6 V
AF in
modulated amplifier
+6 V
Out
modulated-ring pattern See GEAR-WHEEL PAT-
TERN and SPOT-WHEEL PATTERN.
modulated stage A transmitter, amplifier, or oscillator
in which the signal information is impressed
on the carrier.
modulated wave See MODULATED CARRIER.
modulatee A stage or circuit upon which modulation
is impressed (e.g., a MODULATED AMPLI-
FIER or a MODULATED OSCILLATOR).
modulating electrode 1. In an oscilloscope, an
electrode (usually the intensity electrode) to which
a signal can be applied to intensity-modulate
the electron beam. 2. In a cathode-ray tube, the
electrode to which the video signal is applied.
modulating signal Intelligence that modulates a
carrier (e.g., binary data in radioteletype, or music
in broadcasting).
modulation Combining two signals with the result
that some aspect of one signal (the carrier) is varied
by and in sympathy with the other (the modulating
signal). Usually, the carrier has a
frequency considerably higher than that of the
modulating signal.
modulation bars A form of television interference
in which an amplitude-modulated signal causes
horizontal bars, alternating light and dark, to appear
on the picture screen. The higher the modulating
frequency, the closer together the bars
appear. In severe cases, the bars completely obliterate
the picture.
modulation capability The maximum percentage
of modulation a transmitter will permit before