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scanning generator
electron beam in TV camera, image tube, CRT or electronic
display.
scanning generator Timebase controlling scanning (2).
scanning sonobuoy One whose acoustic sensors (either
passive or active) scan to give directional information
and/or to filter out noise from sources other than target.
scanning spot Point of light where electron beam strikes
face of CRT or other scanning field.
scan period Time period of basic scan types other than
conical and lobe-switching, or period of lowest repetitive
cycle in more complex combinations; basic units in US are
o /s, mils/s or s/cycle.
scan stealing Appropriating a main scan for writing
symbols and alphanumerics when interscan period is too
brief; term not recommended.
scan transfer Sudden switching of scanning (3) from
external to internal scene or vice versa, esp. immediately
before bad-visibility touchdown.
scan types There are many varieties of radar scan (1)
patterns. What follows is descriptive of motions of centreline
axis (boresight line) of main lobe only. Each * is
associated with particular type(s) of display, to which
aerial (antenna) az/el information is supplied by potentiometer
or other servo system. Fixed-scan radar points in
one direction only. Manually controlled, points where
directed. Conical, traces out circular path forming smallangle
cone with radar at apex; a variation, spiral, traces
spiral path beginning and ending at centre of circle.
Sector, scans through limited az angle (unidirectional,
from L to R or R to L only, snapping back to start after
each scan; bidirectional, L-R-L-R). Circular, rotates
continuously in horizontal plane (common AWACS
mode). Sector display is circular scan with longpersistence
phosphor in one [important] sector. Helical,
scans continuously in az while winding up and down
elevation from 0° to 90° and back. Palmer is conical scan
superimposed on another, eg Palmer-circular or Palmersector
covers 360° periphery or arc respectively with
conical scans. Raster is TV method of horizontal lines,
usually interlaced; eg an air-intercept 6-bar raster might
scan to R along line 1 (top), to L along 4, to R along 3, to
L along 6, to R along 2, to L along 5 and back to start.
Palmer-raster is another air-intercept scan with conical
scan along two or more horizontal bars; thus 3-bar PR
makes quick rings along top bar, next along middle and
back along bottom, then back via middle to top. Track
while scan (TWS) uses an az radar and an el radar simultaneously
scanning in both planes.
SCAR, Scar 1 Strike control and reconnaissance, co-in
mission (USAF).
2 Strike co-ordinating armed reconnaissance.
3 Sistemi de Control de Armamento (I).
scarf 1 Inclination in vertical plane of cutoff from rod,
tube or other section.
2 Inclination in vertical plane of engine inlet or nozzle,
thus zero-* = vertical.
scarf cloud Thin cirrus draping summit or anvil of Cb.
scarfed Cut off at an oblique angle; hence * joint, inlet,
nozzle etc.
Scarff ring Standard British cockpit mount for handaimed
machine gun 1917-40 with ring-mounted elevating
U-frame.
scarf joint Structural joint, invariably in wood, in which
scatter weapon
mating members are given flat taper to give large
glued/pinned area.
scarifying Increasing coefficient of friction of airfield
surface by cutting shallow grooves, simultaneously
removing rubber and other unwanted residues.
Scarlet Solar concentrator array with refractive linear
element technology.
Scart Syndicat des Constructeurs d’Appareils Radiorécepteurs
et Téléviseurs (F).
scar weight Weight penalty remaining [from brackets,
cables etc] when mission-specific features are removed.
SCAS Stability and control augmentation system.
Scat, SCAT 1 Supersonic civil air transport.
2 Space communications and tracking.
3 Scout/attack helicopter.
4 Speed command of attitude and thrust.
5 Special-category [or single-contractor] aviation
training.
6 Security control of air traffic; ANA adds and air navigation
plan, ER adds and EM radiation (US DoD, 1952).
7 Satellite control of air traffic [oil rigs].
Scatana Security control of air traffic and airnavigation
aids; special provisions and instructions in
time of defence emergency (FAA).
ScATCC Scottish and Oceanic ATC Centre
(Prestwick).
Scatha, SCATHA Spacecraft charging at high altitude[s].
Scat-I Special-category I, capability for Cat.I landings
provided by SLS to all runways within radius of [usually]
30 nm, 56 km.
scatter 1 Distribution, either ordered or, more usually,
random of measured values about mean point (eg of 1,000
measures of wing span of similar type aircraft).
2 Distribution of impact points of projectiles aimed at
same target.
3 See scattering.
scattered cloud Seldom used; cloud amount reported
only in octas, see SCT (1).
scattering 1 Diffusion of radiation in all directions
caused by small particulate matter in atmosphere; effect
varies according to ratio betwen wavelength and particle
size; when this exceeds about 10 Rayleigh scattering
occurs (see back-*, tropospheric *).
2 Trajectory changes of sub-atomic particles caused by
collisions of various interactions; can be elastic or (if there
is energy transfer) inelastic.
scattering loss That part of transmission loss due to
scattering (1) or to target’s rough surface.
scattering power Ratio of total radar power scattered by
target to total power received at target; also called
scattering cross-section.
scatterometer Carried by satellite or aircraft to measure
light reflected from ocean surface to give information on
local wind.
scatter point Geographic point where race competitors
cease to be constrained to narrow take-off corridor.
scatter propagation See back-scatter, tropospheric
scatter.
scatter tolerance That allowed on dimensions of die
forging, often measured at random locations.
scatter weapon One releasing or dispensing many
bomblets or mines.
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