18WuD2x

284 film • filter stopband
film See THIN-FILM MEMORY.
film capacitor A capacitor in which the electrodes
are plated or deposited on the faces of a thin film
of plastic or other dielectric material.
film chain A system designed for the transmission
of movies over a television system. This requires
synchronization of the movie frame rate with the
television scanning rate.
film frame A single picture on a strip of motion
picture film.
film-frame blanking interval The interval during
which a film frame is blanked out as motionpicture
film moves through a camera, projector,
or pickup. The blanking action allows a frame to
move into position without blurring the image as
seen by viewers.
film integrated circuit A monolithic circuit whose
elements are films formed on an insulating substrate.
film pickup A photocell, photodiode, or phototransistor
circuit used to pick up recordings from the
sound track of motion-picture film.
film reader A device for converting data on film
into digital form for a computer.
film recorder An apparatus that records data as a
sound pattern on film. Compare FILM REPRO-
DUCER.
film reproducer An apparatus that plays back
data recorded on photographic film. Compare
FILM RECORDER.
film resistor Also called carbon-film resistor or
metal-film resistor. An electronic component consisting
of a mixture of ceramic, carbon, and/or
metal, applied to a cylindrical form in a thin layer
to obtain a desired value of resistance. The cylindrical
form is made of an insulating substance,
such as porcelain. The film can be deposited on
this form by various methods, and the value tailored
as desired. Metal-film units can be made to
have nearly exact values. Film type resistors usually
have low to medium-high resistance. A major
advantage of film-type resistors is that they, like
carbon-composition units, do not have much inductance
or capacitance. A disadvantage, in
some applications, is that they cannot handle as
much power as the more massive carbon-composition
units, or as wirewound types. Compare
CARBON-COMPOSITION RESISTOR, WIRE-
WOUND RESISTOR.
film scanning The conversion of a movie into a
form suitable for transmission by television.
film speed 1. The speed at which motion-picture
film moves intermittently through a camera, projector,
or pickup, measured in feet or frames per
second. 2. A measure of film’s light sensitivity,
given as an ASA (American Standards Association)
or DIN (European) number; in either system,
the higher the number, the greater the light sensitivity.
filter 1. A circuit or device that passes alternating
currents at some frequencies while attenuating or
blocking currents at other frequencies. Examples:
BANDPASS FILTER, BAND-REJECTION
FILTER, HIGH-PASS FILTER, and LOW-PASS
FILTER. 2. An inductance-capacitance (LC) or
resistance-capacitance (RC) circuit for removing
the ripple from the output of a power-supply rectifier.
3. A transparent disk with special optical
properties placed in front of a camera lens for a
special photographic effect. 4. A character patterned
to control the elimination or selection of
characters in another pattern. 5. A device or program
that separates information, according to
certain specifications or characteristics. 6. A machine
word that specifies the elements to be
treated in another machine word; also called
MASK.
filter attenuation In a selective filter, the power,
current, or voltage loss, in decibels, that occurs
within the passband.
filter attenuation band In a selective filter, the
frequency band(s) outside the passband; that is,
the frequency range over which signals are significantly
attenuated.
filter bank In audio applications, a set of bandpass
filters, each of which covers a specific portion
of the audio-frequency (AF) spectrum. There
is some (minimal) overlap between the passbands
of the filters, so an AF signal of a specific frequency
will always pass through at least one of
the filters, but will never pass through more than
two of the filters.
filter capacitor A capacitor that provides capacitive
reactance in a wave filter or power-supply filter
while also blocking direct current.
filter center A place where information is modified
for transmission to aircraft pilots. Such information
can include weather data, course changes, or
other instructions.
filter choke An inductor that provides inductive
reactance in a wave filter or power-supply filter
while affording relatively easy conduction of direct
current.
filter crystal A piezoelectric crystal used in a
CRYSTAL RESONATOR.
filter cutoff The frequency or frequencies at which
the transmission figure of a filter is below its
maximum value by a prescribed amount, usually
3 dB, representing the half-power point(s).
filter discrimination The amount of fluctuation in
the insertion loss of a bandpass, band-rejection,
high-pass, or low-pass selective filter. The fluctuation
is measured at various points in the filter
passband.
filter inductor See FILTER CHOKE.
filter passband The frequency range over which a
selective filter passes signals with minimum attenuation.
filter reactor See FILTER CHOKE.
filter slot In a waveguide, a slot that acts as a
choke to suppress undesirable modes.
filter stopband See FILTER ATTENUATION BAND.