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PRIMARIES (OF LIGHT)—The three primary colors of light from which all other colors can be derived.
The colors are red, green, and blue [10].
PRIMARY CELL—An electrochemical cell in which the chemical action eats away one of the electrodes,
usually the negative electrode [1].
PRIMARY LOOP—In a cooling system, the primary source of cooling for the distilled water [18].
PRIMARY WINDING—The winding of a transformer connected to the electrical source [2].
PRIME MOVER—The source of the turning force applied to the rotor of a generator. This may be an
electric motor, a gasoline engine, a steam turbine, and so forth [5].
PRINTED CIRCUIT BOARD—A flat, insulating surface upon which printed wiring and miniaturized
components are connected in a predetermined design and attached to a common base [7] [14].
PRISM—A triangular-shaped glass that refracts and disperses light waves into component wavelengths
[10].
PROBE COUPLER—A resonant conductor placed in a waveguide or cavity to insert or extract energy
[18].
PROGRAMMED TRACKING—The method that uses known satellite orbital parameters to generate
antenna pointing angles [17].
PROPAGATION—Waves traveling through a medium [10].
PULSE—Signal characterized by a steep rise from and decay toward an initial level [9] [12].
PULSE-AMPLITUDE MODULATION (PAM)—Pulse modulation in which the amplitude of the pulses
is varied by the modulating signal [12].
PULSE-CODE MODULATION (PCM)—A modulation system in which the standard values of a
quantized wave are indicated by a series of coded pulses [12].
PULSE DURATION (PD)—The period of time during which a pulse is present [12].
PULSE-DURATION MODULATION (PDM)—Pulse modulation in which the time duration of the pulses
is changed by the modulating signal [12].
PULSE-FORMING NETWORK (PFN)—An lc network that alternately stores and releases energy in an
approximately rectangular wave [12] [18].
PULSE-FREQUENCY MODULATION (PFM)—Pulse modulation in which the modulating voltage
varies the repetition rate of a pulse train [12].
PULSE MODULATION—A form of modulation in which one of the characteristics of a pulse train is
varied [12].
PULSE OSCILLATOR—A sine-wave oscillator that is turned on and off at specific times. Also known as
a ringing oscillator [9].
PULSE-POSITION MODULATION (PPM)—Pulse modulation in which the position of the pulses is
varied by the modulating voltage [12].
