Radio annual and television yearbook (1949)

TELEVISION TALK A Modern Glossary (Courtesy Caldw ell-Clements, Inc. & Radio Corp. of America) The advent of television has brought with it a new vocabulary born in the research laboratories, studios, factories — indeed, all parts of the industry. As new techniques are developed, new words and new phrases are coined almost daily. What follows, therefore, is a glossary of the new language of a new and vital part of American life : A AMPLITUDE— The magnitude of any quantity, particularly voltage or current. AMPLITUDE MODULATION— The periodic variation of the voltage or current amplitude in a circuit in accordance with some signal transmitted. Used for television picture. ANTENNA — An electrical circuit for radiating or receiving electromagnetic waves (radio). ASPECT RATIO— The ratio of picture width to picture height. Now 4:3. AUDIO — (I hear.) A term applied to any part of a radio or electrical system handling frequencies in the audible range, normally from 20 cycles to 15,000 cycles. B BAND-PASS FILTER — An electric circuit which will transmit frequencies between two limits and reject others outside those limits. BANDWIDTH — The arithmetical difference between the maximum and minimum frequencies required to convey the information being transmitted, either visual or aural. BLACKER-THAN-BLACK—A portion of the television signal devoted to synchronizing. These synchronizing signals are transmitted at a higher power than the blackest part of the picture, so that they will not appear on the screen. BLANKING — The process of cutting off the cathode ray during the time it is not forming a part of the picture. This occurs when the spot returns from the far right to begin the next line and from the bottom to the top of the picture. BLOCKING OSCILLATOR— A type of oscillator which generates a saw-tooth shaped signal used for scanning in a cathode ray tube. BLOOM — The condition of overall bright illumination of the picture tube obscuring any picture detail. BOOSTER ANODE — A conductive coating placed inside a cathode-ray tube near the screen. Because of a high positive voltage applied, it causes a brighter picture. BRIGHTNESS CONTROL — A control on the receiver for regulating the overall brightness of the picture. C CAMERA TUBE — The electron tube used to translate a scene into electrical impulses. CARRIER — The term applied to the high frequency radio wave which is modulated by the audio and video signals. CATHODE — The electrode in a tube from which electrons are obtained, usually by heating or by photoelectric effects. CATHODE RAY TUBE — An electron tube in which streams of electrons from a cathode are formed into a pencil-like beam and directed by means of electric or magnetic fields over a target, usually a fluorescent screen which glows wherever the beam strikes. CHARACTERISTIC IMPEDANCE— The input impedance of a transmission line infinitely long or a short line terminated in its characteristic impedance. The impedance is independent of length and depends on size of conductor and spacing. CLIPPER — A circuit used to separate signals of different amplitudes. In television these circuits are used to separate the synchronizing pulses from the video signal. COAXIAL CABLE — A particular type of cable capable of passing a wide range of frequencies without the usual prohibitive losses. Such a cable in its simplest form consists of a hollow metallic conductor with a single wire accurately supported along the center of the hollow conductor. CONTRAST — This refers to the ratio of black to white portions of a picture. Pictures having high contrast have very deep blacks and brilliant whites, while a picture with low contrast has an overall gray appearance. 1113