18WuD2x

spiral-rod oscillator • spot modulation 649
spiral-rod oscillator A parallel-line-type oscillator
in which the lines are rods that are rolled up into
spirals to conserve space. Also see LINE-TYPE
OSCILLATOR.
spiral sweep 1. A means of sweeping the electron
beam in a cathode-ray tube to produce a spiral
trace on the screen. 2. The circuit for producing
such a sweep.
spiral trace See SPIRAL SWEEP.
spiral winding See DISK WINDING.
spkr Abbreviation of speaker (see LOUDSPEAKER).
splatter See SIDEBAND SPLATTER.
splatter-suppression filter In an amplitude-modulated
(AM) or single-sideband (SSB) radio transmitter,
a low-pass filter inserted between the
output of the audio amplifier and the audio input
of the modulator. It suppresses high-frequency
audio components that would otherwise cause
sideband splatter.
splaying The construction of a room or auditorium
so that the walls do not meet at right angles. It is
useful in optimizing the acoustic characteristics
of the enclosure because it tends to reduce
acoustic resonant effects.
splice 1. A physical or electrical connection between
two wires, made by tightly winding the
ends together. Solder is often applied for additional
mechanical strength and electrical continuity.
2. A physical connection between two
lengths of magnetic tape, made in such a way as
to cause minimal disturbance in reproduced audio,
video, or data. 3. To prepare a joint, as defined
in 1 or 2.
splicer A device for making a SPLICE.
splicing block A device specifically designed to facilitate
easy splicing of audio, video, or digital
magnetic tape.
splicing tape A durable, flexible adhesive designed
to hold a magnetic-tape splice together.
spline-based modeling In video animation and advanced
computer graphics, a scheme that uses
curve-generating formulas (e.g., Bezier curves) to
create lifelike images.
split-anode magnetron A magnetron in which the
plate (anode) consists of two semicylinders with
the cathode at their axis.
Cathode
Envelope
One-half
anode
One-half
anode
(Magnet not shown)
split-anode magnetron
split-load phase inverter See PARAPHASE IN-
VERTER.
split-phase motor A fractional-horsepower, alternating-current
motor that starts like a two-phase
motor and runs like a single-phase motor. After
the machine approaches approximately 75 percent
of full speed, a centrifugal switch cuts out
the starting winding.
split projector An acoustic transmission device
with several independently operated transducers.
split-reed vibrator See SELF-RECTIFYING VIBRA-
TOR.
split-rotor plate See SERRATED ROTOR PLATE.
split-stator capacitor A variable capacitor having
two separate stator sections and a common rotor
section.
split-sound receiver A television receiver circuit in
which the sound signal is separated from the
composite signal shortly after pickup by the antenna,
and is amplified separately from the video
signal. Compare INTERCARRIER RECEIVER.
splitter A device used to couple two or more television
receivers to a single antenna.
spool See REEL.
sporadic-E layer ionization Occasional, scattered
ionization in the E-layer of the ionosphere.
sporadic-E propagation At certain radio frequencies,
the long-distance propagation of electromagnetic
(EM) waves via the E layer of the
ionosphere. This layer exists at an altitude of approximately
50 miles (80 km) above sea level. This
mode of propagation tends to be intermittent, and
conditions can change rapidly. It is most likely to
occur between 20 MHz and 150 MHz. Occasionally,
it is observed at frequencies as high as 200
MHz. The propagation range is normally several
hundred miles, but occasionally can occur over
distances of 1,000 to 1,500 miles. The standard
frequency modulation (FM) broadcast band is
sometimes affected by this propagation. The
same is true of the lowest television (TV) broadcast
channels, especially channels 2 and 3. See
IONOSPHERE.
SPOT Abbreviation of satellite position and tracking.
spot brightness In a cathode-ray tube, the relative
brilliance of the glowing dot or trace produced on
the screen by the electron beam.
spot check 1. To take a random sample or to make
a random test by arbitrarily selecting a single item
from a run of similar items and subjecting it to
analysis, examination, performance, or parametric
evaluation, etc. 2. A random sample or test.
spot frequency 1. A single frequency or signal to
which other frequencies can be referred. 2. A frequency
or signal that acts as a limit marker (e.g., to
define the edges of an allocated frequency band).
spot jamming Deliberate interference to a radio signal
at some frequency and at some specific time.
spot modulation In a cathode-ray tube, modulation
of the brightness of the spot (and, accordingly,
of the image) produced on the screen by the