Broadcasting (Oct - Dec 1945)

German Film Sound Recording System Offers Depth Illusion FIRST technical information on operation of German broadcasting and communications equipment, based on enemy equipment seized by the United States, has been made available at the Dept. of Commerce. Publication Board of the department is compiling facts on hitherto secret devices for the benefit of American industry. Production techniques more advanced than those used in this country have been revealed in many cases. The Board points out, though, that some products and processes may also be the subject of U. S. patents and patent studies should be made before pursuing practical applications. A film sound recording system said to offer an illusion of auditory depth is described in a report by Lt. H. B. Lee III, USNR, Naval Technical Mission in Europe. It is called the Stereophon and was developed by Dr. Carlheing Becker, of Thansau uber Rosenheim, Germany. Lt. Lee describes him as a capable German physicist who started development of the idea in 1938. In 1942 the Nazi government ordered him to convert it to an explosion power recorder. Work on this was stopped in 1944 and Dr. Becker was ordered to make high-voltage power supplies. He has stated willingness to do developmental work for the Allies. He and his staff of a dozen are described as thoroughly competent, operating a well equipped laboratory and machine shop, undamaged ,and ready to function. Idea of the Stereophon is to employ several mikes during recording and a like number of loudspeakers properly placed for reproduction, providing a stereophonic impression. Two mikes and speakers produce "very great" improvement over one, it is stated; advantage of three over two is not as great, and four over three still less. In application three sound tracks are recorded on film. Each is .7 millimeters wide, with three channels requiring a track of 2.65 millimeters, all that can be accommodated on standard film. Lt. Lee describes operation of the Stereophone as follows : The output of each microphone is fed to a low frequency amplifier capable of accurately passing frequencies from 23 to 10,000 cycles. From each such amplifier, the signal passes to a pair of oppositely connected, diodes which split the signal into plus and minus components. This system of half wave recording is used because it offers a very great advantage in noise reduction. Half-wave recording dates back to 1881. When it is employed, the non-modulated positive sound track is completely dark without resort to "noiseless" equipment and the amplitude of film noise is almost zero. Each half wave signal is then amplified in conventional manner by stages having a band-width of 20 kc because of the harmonic introduced by the phase split. Actual modulation of the light beam that is Impressed on the film takes place In a Kerr Cell. The characteristics of the solution used in this cell (nitro benzene) are such that excessive electrolysis would occur if it were operated by the half wave intelligence frequencies. To avoid this, it is necessary to operate the cell by a higher frequency signal modulated by the half wave intelligence frequencies. Accordingly, a single oscillator stage provides a 170 kc signal to each of six mixer or modulator stages where the 170 kc signal is modulated by the six half wave intelligence bands. Adjustable gain 170 kc amplifiers are provided so that the modulation can be properly controlled. The output of each mixer stage is passed through a band pass filter to eliminate undesired modulation products, and is fed to one plate of the Kerr Cell, which cell serves to wed the electrical and optical systems. The light source is a high pressure mercury lamp giving monochromatic light which is passed through a convex lens to the first of a pair of Nicol prisms. Between the Nicol prisms is the Kerr Cell. In traversing the first Nicol prism, the light is plane polarized and, if no signal were applied to the Kerr Cell, would be completely cut off by the polarizing effect of the second prism. The Kerr Cell, however, has the property of altering the polarization of light traversing it in accordance with an applied signal. Due to this property, light is passed by the seond Nicol prism in an amount that varies with the impressed signal. After leaving the second Nicol prism, the modulated light is focused on the moving negative film by a pair of lenses and the signal is thus recorded. The film drive system is worthy of mention because the possibility of uneven motion, due to film sprockets, is eliminated. Two separate synchronous motor drives are used. One drives the film wind and unwind sprockets and the other drives a transparent wheel over which the film passes to receive the modulated light. Two rubber idlers keep the film up against this latter wheel and insure that there is no sprocket effect at this point. The effect of the wind and unwind sprockets is insulated by loops of film between these sprockets and the transparent wheel. The speed of the transparent wheel can be varied mechanically using a. a variable ratio drive so that the proper amount of looping can be obtained. Essential data on the recorder are: Signal Frequency Range — 23 to 10,000 cycles. Dynamic Range — 60 db without resort to expansion and compression. Distortion — Less than 3% over the whole dynamic range. Film Noise — 70 db below greatest amplitude. Film Velocity — 45 cm/sec. Sound Track Width— 2.65 mm. Price Reports German Observations to Truman REPORT of Byron Price, former Director of the Office of Censorship, based on his mission abroad to study relationship between German civil population and the American Army of Occupation, has been submitted to President Truman. It will be made public in due time the President said at his Tuesday news conference. Mr. Price discounted statements that his report was being held up because it contained "dynamite". It is thought the report may contain information on the place broadcasting takes in postwar Germany. Symphonies on American SYMPHONIES FOR YOUTH, weekly 45minute series under auspices of Southern California Symphony Assn., starts on American stations on Jan. 12. Program will air from Los Angeles Philharmonic Auditorium, with Alfred Wallenstein, symphony conductor. Audience is to be entirely composed of students. Intermission musical quiz is conducted by Thomas Freebairn Smith. FARM SAFETY RADIO GROUP MEETS DEC. 3 DIRECTORS of the National Safety Council's Farm Safety Radio Committee will discuss plans for the third national Farm Safety Week at luncheon Dec. 3 at the Stevens Hotel, Chicago. Everett Mitchell, agricultural director of NBC central division and chairman of the Council's committee, will emphasize the importance of National Farm Safety Week, July 21-7, 1946, as part of campaign in response to President Truman's request that the Council continue its war against accidents. Labor FM (Continued from page 20) change among the union's four proposed stations. Stock in Amalgamated Broadcasting System is divided in 20% blocks among Amalgamated Clothing Workers and its joint boards in New York, Chicago, Rochester and Philadelphia. UAW 10 days ago authorized expenditure of $400,000 for establishment of the six stations it proposes [Broadcasting, Nov. 19]. The applications, originally filed a year ago, estimate installation costs at $110,000 each in Newark, Chicago, Cleveland, Los Angeles, and Detroit, and $34,250 in Flint. Monthly operating costs of $6,700 and revenue of $13,500 were estimated for the stations in Newark, Chicago, Cleveland and Detroit. Flint application estimates monthly costs at $3,240 and revenue at $6,750. Operating costs and revenue are not estimated for the Los Angeles station. The UAW stations would operate 18 hours daily. At least 25% of programming would be educational and would provide opportunity "for the maximum of free discussion to all groups and classes without discrimination." ILGW officials said $250,000 had been set aside for establishment of its proposed stations, and that $200,000 more could be borrowed to carry them over their early operations. They said the stations, after selling enough time to make them self-sustaining, would devote the bulk of their broadcasts to social, cultural, and spiritual programs. Chicago Federation estimated that installation of its proposed FM station would cost $30,405. There was no estimate of operating cost or revenue. With no commercial programs at the start, shows would be about 70% musical, 20% educational, and 10% news. It would operate eight hours daily. Peoples Radio Foundation Inc. said the station it seeks in New York would operate eight hours daily, with 55% of its schedule commercial and 45% sustaining. Programs would include entertainment, educational, fraternal, and religious broadcasts and news. Initial cost was estimated at $19,500; monthly operating, at $2,700. It's The YIELD That Counts In Mississippi, we think in terms of yields because we live in an agricultural economy. Cotton acres in Mississippi almost double the yield of the largest cotton-producing state. The sweet potato yield per acre is the largest in 16 years, and the corn crop was 6^/2 million bushels larger than the 1944 crop. These are cash crops! Alert advertisers find they get a comparable yield on advertising dollars spent in this State of Opportunity. WJDX — the DOMINANT "Voice of Mississippi" effectively, efficiently covers this growing market. . LAMAR LIFE INSURANCE \ COMPANY ; JACKSON, MISSISSIPPI 4,955,144 spindles spinning VICTORY ...daily producing cotton cloth to wrap around the world. Produced from "picker to bolt" in the 16-county WSPA Primary Area. WSPA SPARTANBURG, SOUTH CAROLINA Home of Camp Crofl 5000 watts Day, 1000 watts Night 950 kilocycles, Rep. by Hollingberv BROADCASTING • Telecasting November 26, 1945 • Page 85