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April 18. 1931
MOTION PICTURE HERALD
13
REGULAR BROADCASTING METHODS REQUIRE BAND OF 4 MILLION CYCLES
T ransmitted By Usual Methods
Fig. 4 — By using ten ordinary broadcast channels, and transmitting 6250 elements, the appearance would be as above.
Fig. 5 — By employing twenty ordinary broadcast channels greater detail is gained as indicated in the group above.
Monopoly of Transmitting Channels Necessary
Some Minor Inroads in Home Field Expected to Materialize in the Next Two or Three Years
{Continued from preceding page)
Gannett, an important factor in television development for American Telephone & Telegraph, outlines the surface workings of television transmission and their relations to the quality of images.
By D. K. GANNETT
American Telephone & Telegraph Co.
In the procesbcs usually employed in telephotography, the picture may be considered to be divided into a large number of small, etjual-sized elements like a mosaic. Unlike the human eye, which sees the whole picture at once, the electrical eye of the transmitting machine is focused on only one element at a time, passing rapidly along row after row lit elements until the whole picture has been scanned. As each element is viewed in turn, an electrical signal is sent out whose strength corresponds to the average shade of that element. Upon reception of the signals, the receiving apparatus re-creates the picture elements one at a time, painting each dark or light as directed by the electric signals, and arranges them in the proper order to form a picture similar to that viewed by the transmitter.
It is apparent that, in such a system, picture details smaller or closer to.Eether than (Continued on page 33)
Fig. I-B — Picture transmitted over the commercial telephotograph system containing 250,000 elements.