An automatic preset television program switching system allows video signal, audio signal and projection system to be set-up in the desired sequence in advance of air-time. This permits an increase in number of switches, more complex integration and most important flawless switching during the commercial time periods between or during programs.
The side-fire helical antenna, successfully used for UHF and VHF high channel television transmission, has now been adapted for low channel VHF service. Investigation of properties of a helical radiator wound around a polygonal supporting structure has made possible the required increased bandwidth and provided directional patterns for special TV coverage applications. Through scale model work, a channel 2 directional antenna has been developed for installation around a triangular tower section.
The undesired effects of co-channel television interference vary both with the intensity and the frequency of the interfering signal. It is found that there are three types of frequency-variation of objectionability, namely: (1) A progressive decrease of objectionability as the frequency of the undesired signal is shifted away from the carrier frequency of the desired signal, which we have called the Beat Size Effect; (2) superimposed on the Beat Size Effect there is a cyclic variation in objectionability which repeats at intervals corresponding to the horizontal scanning frequency; and (3) superimposed on each of these variations there is a ``finegrain'' cyclic variation which repeats at intervals corresponding to the vertical scanning frequency. We have called the cyclic variation (2) and (3) Beat Pattern Effects. Advantage may be taken of the Beat Size Effect and the Beat Pattern Effects to reduce co-channel television interference by appropriate specification of the operating frequencies and frequency tolerances of the desired and undesired stations. It is shown that it is also possible to reduce the objectionable effects of co-channel television interference by the use of certain post-detection devices in the television receiver. Narrow-band video filters, high-pass video filters, and diode clamp video correction circuits have given promising results.
A few years ago, commercial television made its appearance as a dominant economic and cultural force on the American scene. At about the same time, tape recorders emerged as the unparalleled mediun for the reproduction of sound. Commencing with this loosely defined milestone, engineers, production people, station owners, and sponsors looked forward to the use of tape for the recording of television programs.
In television cameras employing image orthicon tubes, the problem of picture sticking or image retentivity often limits the effective life of these tubes. Methods are discussed which minimize this problem by slowly rotating the image on the tube in a small circular orbit by either optical or electronic means for color or monochrome cameras.
Present day broadcast program practices have brought about more complex operational requirements with the result that less effort can be devoted by the operator to maintaining a desirable constant audio level.
A high-efficiency all-transistor regulated power supply for 280 volts and 1.5 amperes is compared with conventional supplies using vacuum tubes. Test results show good characteristics for video use with size and weight reduced by a factor of two.
Image orthicons and vidicons have been improved substantially to fulfill requirements for better TV broadcasting. The advantages of ``micromesh'' and ``super-dynodes'' are explained and the performance characteristics of a new image orthicon with very high photocathode sensitivity described. Recommendations concerning studio practices to obtain best black-and-white and color pictures are presented.
The Television Allocations Study Organization was established, at the request of the Federal Communications Commission, by five of the major associations in the television industry. The objective of TASO is to make a thorough study of the engineering factors affecting the allocation of channels for television broadcasting. To carry out this task, six engineering panels have been formed. Each is working on a specific phase of the overall problem (1) transmitting equipment, (2) receiving equipment, (3) field tests, (4) wave propagation, (5) analysis and theory, and (6) levels of television picture quality. A total of 174 engineers from 92 organizations from all branches of the television industry are serving on TASO panels. The work of the panels is progressing rapidly and it is expected that significant results in the form of reports for the use of the FCC and the television industry will be forthcoming by the middle of next year.