Two-Way Television

An experimental two-way television system in combination with a telephone service has been installed between two buildings in New York. With this system, two people can both see and talk to each other. It consists in principle of two complete television systems of the sort previously used for one-way transmission. Scanning is accomplished by the beam-scanning method using disks containing 72 holes. Purple light, to which the photo-electric cells used are quite sensitive, is employed for scanning, and a yellow-green light is used for illuminating the television booth. High-intensity neon lamps are used with a condenser lens disk at the receiving end to give an image brilliant enough to be seen without interference from the scanning beam. A frequency band 40,000 cycles wide is required for each of the two television circuits. Synchronization is effected by a 1275 cycle alternating current, controlling synchronous motors rotated 18 times per second. Speech is transmitted by microphones and loud speakers concealed in the television booths so that no telephone instrument interferes with the view of the face.

Print ISSN

0097-5834

Published

1931-03

Content type

Original Research

DOI

10.5594/J13011