Showing papers in "IEEE Transactions on Broadcasting in 1987"
TL;DR: A Doherty system combines the outputs of two or more linear RF power amplifiers through an impedance-inverting coupler such as a quarter-wave transmission line and can be considerably more efficient than a conventional class-B linear PA.
Abstract: A Doherty system combines the outputs of two or more linear RF power amplifiers (PAs) through an impedance-inverting coupler such as a quarter-wave transmission line. At low output levels, the first PA operates linearly, reaching saturation (and maximum efficiency) at some transition voltage below the system peak-output voltage. At higher output levels, the first PA remains saturated and the second PA operates linearly. The instantaneous efficiency and power characteristics of a Doherty system are derived using ideal class-B RF PAs so that the results can easily be scaled for use with real-world PAs. The average efficiency and maximum-efficiency transition points are then determined for a variety of amplitude-modulated signals. The Doherty amplifier can be considerably more efficient than a conventional class-B linear PA. For example, the 28-and 8.9-percent average efficiencies of a class-B PA with Rayleigh-distri buted envelopes with 10-and 20-dB peak-to-average ratios are improved to 60 and 48 percent, respectively, by a two-stage Doherty system. The addition of a third stage further improves the efficiencies to 70 and 66 percent, respectively.
400 citations
TL;DR: An HDTV broadcasting service on one satellite broadcast channel became available after the development of a transmission system called MUSE involving bandwidth compression.
Abstract: An HDTV broadcasting service on one satellite broadcast channel became available after the development of a transmission system called MUSE involving bandwidth compression. Using MUSE, a satellite channel of width 27 or 24 MHz in the 12 GHz band can carry an HDTV picture, digitally-coded four-channel sound and independent digital signal at about 100 Kb/s.
100 citations
TL;DR: How the four components of the widescreen high-definition signal are processed to insure full compatibility at the NTSC receiver and complete recoverability at the ACTV receiver is discussed.
Abstract: This paper describes an advanced compatible television (ACTV) system intended for the single-channel transmission of widescreen EDTV images. Existing NTSC receivers display a selected 4: 3 portion of the widescreen image with standard NTSC resolution. However, a new widescreen receiver, tuned to the same 6-MHz RF channel, displays a widescreen image with a resolution in excess of 400 lines/picture height in both spatial dimensions. To produce the NTSC-compatible signal, the original widescreen high-definition signal is separated into four components: (1) the main NTSC signal with the side panel low frequencies time compressed into the horizontal overscan regions, (2) the time-expanded side panel high frequencies, (3) the extended horizontal-luminance detail, and (4) the extended vertical-temporal luminance detail. Components 2 and 3 are quadrature modulated at low amplitude by a new phase-controlled subcarrier at 3.1 MHz. Component 4 is inserted in quadrature with the RF picture carrier. This paper discusses how the four components are processed to insure full compatibility at the NTSC receiver and complete recoverability at the ACTV receiver.
43 citations
TL;DR: This paper describes NTSC compatible HIDTV systems with incremental improvement potential, capable of increased horizontal and vertical resolution, reduced crosstalk between the components, and a wide aspect ratio.
Abstract: This paper describes NTSC compatible HIDTV systems with incremental improvement potential. The systems are capable of increased horizontal and vertical resolution, reduced crosstalk between the components, and a wide aspect ratio. Experimental results on a split-luminance system show that 600 lines of horizontal resolution are achieved after the luminance signal band has been divided at the encoder and recombined at the decoder. Spatial splitting of the picture is employed to increase the aspect ratio. A low cost HDTV system is also presented that uses a modulated-signal combination. With this system, considerable simplification is possible with a slight reduction in resolution. All proposed systems are fully NTSC compatible and utilize two standard 6 MHz channels for transmission. The improvements can be realized incrementally because of their downward compatibility at the receiver.
19 citations
TL;DR: In this paper, a vertically installed planar planar circuits were described for the purpose of making low-cost microwave circuit in mass production, where 3 dB-directional coupler and filters were described together with their applications.
Abstract: In this paper, a newly proposed vertically installed planar circuits are described This circuits were developed for the purpose to make low cost microwave circuit in mass production As examples, 3 dB-directional coupler and filters are described together with their applications
14 citations
TL;DR: The error control mechanism, based on Reed-Solomon product code, worked sufficiently well with the overhead for parity, sync code and ID code in the blanking period, and no picture quality degradation has been observed.
Abstract: This paper describes the technical details of an experimental HDTV digital VTR with a bit rate of 1.188 Gbps. This newly developed machine satisfies the proposed parameter values in the CCIR Report 801. The basic technologies developed to achieve such an ultra-high speed recording are: metal particle tape and Sendust sputtered type head, a high performance head assembly, and parallel signal processing. Using 8 recording heads, the recording rate per channel is 148.5 Mbps and the minimum recording wavelength is 0.69 pm. The error control mechanism, based on Reed-Solomon product code, worked sufficiently well with the overhead for parity, sync code and ID code in the blanking period. Even after 20th generation dubbing, no picture quality degradation has been observed.
11 citations
TL;DR: A bi-channel HDTV transmission system has been developed that digitally filters the video signal in accordance with known spatiotemporal properties of the bi- channel visual of system, resulting in compatibility with existing broadcast systems and improved spatial resolution for both moving and stationary HDTV images with a reduced bandwidth.
Abstract: A bi-channel HDTV transmission system has been developed that digitally filters the video signal in accordance with known spatiotemporal properties of the bi-channel visual of system. Differential processing of high and low spatial-frequency information yields several distinct advantages that include: compatibility with existing broadcast systems and improved spatial resolution for both moving and stationary HDTV images with a reduced bandwidth.
11 citations
TL;DR: A coding system developed for sound transmission accompanying the MUSE system HDTV picture is described.
Abstract: A coding system developed for sound transmission accompanying the MUSE system HDTV picture is described
10 citations
TL;DR: This paper presents an economically attractive system for the hierarchical evolution of High Definition Television (HDTV) compatible with the NTSC installed base and proposes this emission system as a means for transmitting HDTV pictures to consumers on the North American continent.
Abstract: This paper presents an economically attractive system for the hierarchical evolution of High Definition Television (HDTV) compatible with the NTSC installed base. It describes the two main signals of this system: HDMAC-60 and HDNTSC. The first, HDMAC-60, is a feeder signal for use between the program origination and program redistribution points, and used also as a DBS emission format. The second, HDNTSC, is a delivery signal for high definition terrestrial broadcast, CATV distribution and VCR plus laser video disc applications. We propose this emission system as a means for transmitting HDTV pictures to consumers on the North American continent.
5 citations
TL;DR: The balance of power for the high efficiency design, representing the normalized maximum output power and the efficiency versus the conducting angle or other parameter, are compared.
Abstract: The paper investigates the drive-wave shape influence on the performances of tuned HF high-power amplifiers. Using the linear model of high-power HF triode and changing the drive wave shape (cosine, triangular, trapezoidal and pulse) under the same conditions (conducting angle, drive level), the balance of power for the high efficiency design, representing the normalized maximum output power and the efficiency versus the conducting angle or other parameter, are compared.
5 citations
TL;DR: An optional technique widens the image aspect ratio and creates bandwidth within the original NTSC standard large enough to transmit a digitally-encoded stereo audio signal to match the improved visual characteristics.
Abstract: This paper describes a new process referred to as HD-NTSC?. This signal has all the appearances of a conventional NTSC signal, and can be edited, stored, transmitted, and received by conventional NTSC equipment. A receiver constructed to interpret the HD-NTSC protocol will be able to build an ID-NTSC image having substantially improved resolution in both the vertical and horizontal axes for those parts of the imnage that are nearly stationary over time. Those parts of the image exhibiting motion will show resolution equivalent to a conventional top-quality NTSC picture. The HD-NTSC receiver will also display the image at 60 frames per second, eliminating most interlace and flicker defects. An optional technique widens the image aspect ratio and creates bandwidth within the original NTSC standard large enough to transmit a digitally-encoded stereo audio signal to match the improved visual characteristics.
TL;DR: Satellite television systems may employ subcarriers for additional transmission of data via the same channel thus utilizing satellite transponders more efficiently, and data-rate and bit-error-rate are ultimately limited by maximal-permissible subcarrier levels.
Abstract: Satellite television systems may employ subcarriers for additional transmission of data via the same channel thus utilizing satellite transponders more efficiently Data-rate and bit-error-rate of such systems are ultimately limited by maximal-permissible subcarrier levels which would not degrade the picture quality significantly
TL;DR: The opportunity for HDTV distribution extends beyond broadcast and cable technologies to VCR tape and video disc, and the possibility exists that these distribution industries might be bypassed unless a practical HDTV signal format is devised.
Abstract: During the last few years there has been increasing interest in the use of high-definition television (RDTV) equipment to reduce costs in programme production. It is also clear that the wider aspect-ratio of HDTV, and the absence of picture impairments, would be very attractive to many consumers if delivered at the right price. In fact, it is not unreasonable to suggest that a successful system for the delivery of HDTV to the public could both differentiate and enhance the value-of the programming supplied, and give rise to the next generation of consumer TV sets. Moreover, the opportunity for HDTV distribution extends beyond broadcast and cable technologies to VCR tape and video disc. Therefore the possibility exists that these distribution industries might be bypassed unless a practical HDTV signal format is devised.
TL;DR: In order to develop sound systems for HDTV, experiments were carried out with seven sound reproduction systems to assess their sensation of reality, sound spaciousness and other qualities and suggest that it is desirable to use four sound signals in order to reproduce a better sensation ofreality.
Abstract: In order to develop sound systems for HDTV, experiments were carried out with seven sound reproduction systems to assess their sensation of reality, sound spaciousness and other qualities. The results suggest that (1) it is desirable to use four sound signals in order to reproduce a better sensation of reality, (2) it is desirable to use three sound signals in front of observers and one sound signal at the rear of observers in order to maintain a better correspondence between the picture direction and the sound localization.
TL;DR: In this paper, a method for feeding two-tower arrays is described, where the self-impedance of each tower and the mutual impedance between the towers are known, and the feed-point voltage at each tower can be calculated for an assumed set of base currents.
Abstract: This paper describes a novel method for feeding two-tower arrays. If the self-impedance of each tower and the mutual impedance between the towers are known, then the feed-point voltage at each tower can be calculated for an assumed set of base currents. When a transmission line of specified impedance is connected to the base of each tower; the voltage at any point on these two lines can be calculated using transmission-line theory, since the loadend voltages are known. If the voltage phasor at some point on one of the lines is identical to the voltage phasor at some point on the other line, then each antenna feeder can be cut at that particular point and the two ends joined together. The resulting impedance at this "common point" can be transformed to 50 ohms (or any desired value) by a matching network which then connects to a single transmission line extending back to the transmitter. Software for implementing the technique either on a personal computer or programmable calculator is included for those who are interested.
TL;DR: Satellite television channels often employ multiple subcarriers which are usually located above the main audio subcarrier thus utilizing higher baseband frequencies, and conventional click models fail to describe the FM-threshold effect accurately.
Abstract: Satellite television channels often employ multiple subcarriers which are usually located above the main audio subcarrier thus utilizing higher baseband frequencies. At these frequencies conventional click models fail to describe the FM-threshold effect accurately.
TL;DR: To ensure interference-free C band' reception under the present 20°, spacing requirement, the results indicate that the receiving antenna diameter should not be smaller than about 11 feet, and only by increasing the antenna size to 16 feet or larger is it possible to achieve improvement over an 11 foot antenna.
Abstract: The crowding of the orbital arc with the attendant imposition by the FCC of the 20 orbital spacing requirements between satellites will end the trend toward smaller satellite home receiving antennas. Smaller antennas (less than 10 feet in diameter), which are subject to interference from adjacent satellites, will be replaced by larger antennas. In this paper the expected interference is calculated, and the resulting received signal-to-noise ratio is estimated. To ensure interference-free C band' reception under the present 20°, spacing requirement, the results indicate that the receiving antenna diameter should not be smaller than about 11 feet. In high satellite EIRP cases, only by increasing the antenna size to 16 feet or larger is it possible to achieve improvement over an 11 foot antenna. For sizes between 11 and 16 feet, performance degrades in comparison with an 11 foot antenna because the interference falls onto the antenna's side lobes and is not sufficiently attenuated.
TL;DR: A new approach to the practical design and realization methods of linear phase emphasis network, which is applicable to the FM transmission system, is introduced, based on employing the Gaussian function expressed as a real exponential function exp(P2) realized by the squared amplitude response of a specific two-port passive LC ladder network.
Abstract: In this paper, a new approach to the practical design and realization methods of linear phase emphasis network, which is applicable to the FM transmission system, is introduced. The methods are based on employing the Gaussian function expressed as a real exponential function exp(P2) realized by the squared amplitude response of a specific two-port passive LC ladder network. They are also based on a time base conversion technique using digital technology which provides a zero phase network.
Journal Article•
TL;DR: One of the most sought-after improvements in HDTV equipment is better VTR picture quality through digital recording, which is free from picture quality degradation in the recording and playback processes.
Abstract: One of the most sought-after improvements in HDTV equipment is better VTR picture quality. A promising way to achieve this is through digital recording, which is free from picture quality degradation in the recording and playback processes.
TL;DR: In this paper, the optimal design of the high power plate and grid modulated selective amplifier is examined, and the estimated characteristic values of this high power and high efficiency HF amplifier are shown in the corresponding diagrams.
Abstract: The optimal design of the high power plate and grid modulated selective amplifier is examined in this paper. For the analysis purposes, the linear model of constant plate current characteristics for HF power triode is applied. The carrier wave state of the unmodulated amplifier is chosen so to enable the realization of the high levels of modulation. The results are obtained immediateZy, and the estimated error is acceptable. The estimated characteristic values of this high power and high efficiency HF amplifier are shown in the corresponding diagrams.
TL;DR: On passe en revue les nouvelles technologies principales appliquees a la television depuis son apparition dans les foyers des Etats-Unis, au debut des annees 60.
Abstract: On passe en revue les nouvelles technologies principales appliquees a la television depuis son apparition dans les foyers des Etats-Unis, au debut des annees 60
TL;DR: At this point in time, with the advent of high powered Ku band direct broadcast satellites (DBSs) and the ever increasing requirement for TV via satellite, it is safe to say that satellite rooftop receiving antennas will soon shrink in size.
Abstract: At this point in time, with the advent of high powered Ku band direct broadcast satellites (DBSs) and the ever increasing requirement for TV via satellite, it is safe to say that satellite rooftop receiving antennas will soon shrink in size. This will be true for DBS systems operating in the Ku DBS band, since Ku band EIRP has been increased considerably over C band EIRP. It will not necessarily be true for Ku band satellite systems operating in the broadcast satellite service band, where maximum power flux density, and therefore EIRP, is limited.
TL;DR: In this article, a method of producing (utilizing the quadrature modulation) and demodulating (with the Costas detector or PLL loop) of a new AM stereo signal of the waveform (1+L+R) cos (wt+?) has been discussed.
Abstract: A method of producing (utilizing the quadrature modulation) and demodulating (with the Costas detector or PLL loop) of a new AM stereo signal of the waveform (1+L+R) cos (wt+?) has been discussed, where: ?= 0.5 arc sin r[(L-R)/(l+L+R)], L and R -stereophonic signals.
TL;DR: The Japan Broadcasting Corporation has announced it will begin direct satellite broadcasting of high definition television (HDTV) in Japan in 1990, and consumer HDTV equipment will be sold in Japan, and likely elsewhere, at that time as discussed by the authors.
Abstract: Technical development of advanced television systems has reached a level where major changes in consumer products can be expected on the market in the foreseeable future. Super VHS, already being sold, offers pictures from prerecorded tapes which are significantly better than can be delivered via conventional broadcast. The Japan Broadcasting Corporation has announced it will begin direct satellite broadcasting of high definition television (HDTV) in Japan in 1990, and consumer HDTV equipment will be sold in Japan, and likely elsewhere, at that time.
Journal Article•
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TL;DR: A scheme to modify NTSC video signals to render the signal unrecordable by video recorders, yet viewable on standard television displays is proposed, based on continually varying timing characteristics in the transmitted video signal.
Abstract: Proposed in this paper is a scheme to modify NTSC video signals to render the signal unrecordable by video recorders, yet viewable on standard television displays. This method is based on continually varying timing characteristics in the transmitted video signal. Protection of copywrited broadcast material from casual consumer or illicit professional recording would be possible with this implementation. A means of neutralizing this protection scheme would require extensive signal buffering and analysis hardware currently beyond the reach of nearly all unauthorized parties.
TL;DR: The growth in numbers of commercial communications satellites in geosynchronous orbit raises the possibilities for radio frequency interference into space-earth transmission systems due to a malfunctioning satellite and of physical damage to an operating satellite due to collision with co-orbiting objects.
Abstract: The growth in numbers of commercial communications satellites in geosynchronous orbit raises the possibilities for radio frequency interference into space-earth transmission systems due to a malfunctioning satellite and of physical damage to an operating satellite due to collision with co-orbiting objects. These possibilities are addressed and recommendations are presented to minimize such occurrences.
Journal Article•
TL;DR: This paper describes a novel method for feeding two-tower arrays if the self-impedance of each tower and the mutual impedance between the towers are known, then the feed-point voltage at each tower can be calculated for an assumed set of base currents.
Abstract: Alimentation du reseau equiphase constitue de deux antennes d'un emetteur de radiodiffusion