Movies for TV - Early Television Foundation

CHAPTER
PRINCIPLES OF TV
Before proceeding any further, the manner in which pictures and
visual intelligence are sent via the airwaves should be described.
While it is not strictly necessary for those persons engaged in the
program side to know exactly how television works, it is an aid to
the more sensible use of the medium, for utterly impossible demands
can be avoided if some of the difficulties which plague the engineer
are understood.
In sound broadcasting, or recording, a microphone is used to
convert sound waves to electric waves. In movies, a film camera is
used to make light and shadow effect minute chemical changes in
a silver emulsion on a strip of celluloid. In television, a combination
of the electric microphone and movie camera technique is used to
produce an electric current which varies according to the picture
being transmitted.
A television station may be divided into five sections of equipment
used to produce and transmit television pictures. The first is
the transmitter section where signals from the studios are amplified
and impressed on a carrier wave which is transmitted. Next is the
antenna, which is usually 500 feet or more above the ground and
often mounted on a high building by means of a steel tower on top
of the building, or else on a separate tower on high ground. Then
comes the studio section which contains studios in which the pro-
grams arc produced and control rooms where the signals from dif-
ferent cameras and studios including the film studio are mixed.
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