A problem which urgently needs solving is that of the tremendous waste in bandwidth created by our present nonstatistical analog system of television transmission. Attempting to reduce bandwidth while maintaining the same channel capacity is seen to yield poor results.
The Telechrome-JVC 2-Head Video Tape Recorder is quite unusual and different when it is compared to other VTR's. It has a number of features not found in any other video tape system of recording. Some of these are as follows: 1. Ability to obtain pictures with the tape running slowly, standing still, or even running in reverse for obtaining special effects. 2. Ability to simultaneously record, monitor, and playback while recording, allowing optimum recording adjustments to be made while recording and also, at the same time, being able to make sure the picture is "in the can". 3. There is inherently no horizontal banding, scalloping, skewing, or venetian blinding of the pictures because of the recording method used. 4. Because of the design philosophy, first cost as well as maintenance costs are drastically lower than transverse type head recorders; lower priced individually replaceable heads, lower tape costs, simpler circuitry as well as a processing amplifier not being required. 5. The great ease in obtaining still frame pictures allows precise editing to be done.
A realistic engineering comparison of the service which can be provided at VHF and UHF is essential in the formulation of a television allocations plan. The critical technical factors are wave propagation, receiver noise figure, receiving antennas, interference, and transmitter power. A consideration of these factors leads to the conclusion that the service provided by the 70 UHF channels is far less than 70/12 times the service provided by the 12 VHF channels. It is suggested that VHF service may be increased by the use of directional transmitting antennas, and UHF service by the development of satisfactory on-channel boosters.
Although the 5820 Image Orthicon received universal acceptance in the United States of America as the camera tube for studio and remote telecasts, its progress in Europe was impeded due to the existance of other picture originaing equipment which produced pictures superior in all respects other than sensitivity. As a result, considerable modification of the image orthicon tube was undertaken, culminating in the develoment of the 3 inch field mesh and 41/2 inch image orthicon tubes.
The use of video tape recording equipment has increased the requirements for higher quality performance from image orthicons. The GL-8093 and its characteristics are described as a 3-inch image orthicon to meet this need. The GL-8092, a field-mesh version of the high sensitivity image orthicon, is described for color applications.
The Federal Communications Commission is in the process of conducting a test of UHF television in New York City to determine the technical and economic feasibility of using this band to provide satisfactory television service to large cities with special emphasis on the canyon areas of such cities. This paper summarizes the Project organization and provides a progress report. Since the transmitting installation has just been brought into a near completion stage, and the Project will last for another year, this is a discussion of the method of attack rather than a report of results obtained.
In order to realize the advantages which solid state devices may bring to television broadcast operations, a program has been undertaken to provide solid state modular components in building block form for television broadcast terminal equipment, featuring low power consumption, small size and great reliability.
Tube Registration. In recent years there has been considerable advancement made in the field of vidicons. If the number of tubes is to serve as an indication of advancementa rather dubious criterion, I thinkthen there has indeed been much progress made. There are more than 20 vidicon types registered with EIA and at least an equal number of tubes with private labels by both American and foreign manufacturers. In addition, there are many experimental and developmental types still in the laboratory stage. No attempt will be made to cover this latter group if indeed such were possible. The rate of vidicon type registration is, to some extent, indicative of industry activity. Figure 1 shows the number of registrations by year; the rapid rise in rate in the past few years is apparent. Hopefully, the current standardization activity by the cognizant engineering committee of the Joint Electron Devices Engineering Council (JEDEC) will help reduce the rate without impeding technological advancement.
Network radio broadcasting has changed considerably compared to the pre-television era. Fifteen years ago, the public looked toward radio for a complete repertoire of music, drama, comedy, and news. The affiliate stations were on the network most of the time and bulletins or special programs were automatically received. Any communications from network headquarters to the stations could be handled during station breaks. Now, however, the stations are off the network most of the time, and there is no simple way to alert these stations to receive urgent news bulletins or national emergency announcements.
Observations on the use of both high and low-frequency precision offset for interference reduction have not indicated any severe problems due to propagation at least for Channel 4. Arrangements are being made for further observations on high VHF channels.
The standard type VU meter has for many years been employed almost exclusively by broadcasters in the United States as a program level indicator. A new unit which should give better indication of peak loudness has now been developed and is being evaluated. This unit operates within the range of time constants specified by the FCC for transmitter aural modulation meters. A field test is now in progress, with a number of the new indicators in various studios throughout the country.
The Voice of America, the international broadcasting service of the U. S. Information Agency, speaks for America in thirty-five different languages to a worldwide audience. The technical facilities that make this possible literally encircle the globe. Thirty shortwave transmitters at seven locations in the continental United States range in power from 25 to 200 kilowatts. Overseas, the VOA has nine relay stations with forty-seven transmitters ranging in power from 35 to 1,000 kilowatts. This presentation discusses the development of this technical system from its war-time inception. Highlighted in the discussion are the problems encountered in the development of the system, the techniques designed to counteract these obstacles, and future plans for strengthening the signal of the Voice of America.
Uniform terminology and a method of graphical representation are established. Factors affecting exposure uniformity are described by reviewing fundamental relations between the film exposure cycle and the television scan. Practical arrangements for recording television pictures on motion-picture film are described and analyzed. Effects of phosphor persistence are considered, and a detailed analysis of persistence effects in single-field recording is offered.
Experiments with a slope-feedback variable-velocity-scanning method for compressing the bandwidth of television signals are described. The test conditions were intended to demonstrate the method under favourable conditions and one test-pattern of moderate complexity-test-card 'C'-only was used. The experiments showed that smoothing of the signal by narrow bandwidth can be overcome using the method. But, even at best (corresponding to the least compression ratio observed = 1.7/1), spatial distortion of the received picture is noticeable.
A computer program developed and used by the Department of Transport to determine nighttime sky wave signal interference to ground wave service is described. The formulas and sequences used by the program are discussed. A sample calculation of the program is given. The advantages of such a program, to the broadcast design engineer, are accuracy, reliability, speed and convenience.