Digital High-definition Television Research Articles

The Introduction of HDTV into Digital Television Networks

The development of larger displays with higher spatial and/or temporal resolution, combined with the need to differentiate new digital services from existing ones, has led to a new drive toward digital high-definition television (HDTV) transmissions. To deliver better picture quality into the home, it has been proposed to start HDTV transmissions (with upconversion at the studio output) despite the fact that much production will remain at standard resolution for the foreseeable future. This paper demonstrates that early adoption of HDTV transmissions is unlikely to achieve the highest picture quality in the home at first, due to uncertainties in the display format. It is shown that upconversion should be matched to the display process and thus achieve a better picture quality. If the consumer display supports only standard resolution, the combined effect of upconversion, compression, and downconversion is shown to lead to severe degradation in picture quality. Furthermore, additional factors such as the increase in required transmission bandwidth are also discussed.

The HDTV Broadcast Standard: Subjective Evaluation of Proponent Systems

Six high-definition television (HDTV) systems were tested to establish a proposed HDTV terrestrial transmission standard. The tests occurred in two rounds and were conducted at the Advanced Television Test Center (ATTC); and at Cable Labs in Alexandria, VA; and at the Advanced Television Evaluation Laboratory (ATEL) in Ottawa, Ont., Canada. The testing process played an important role in accelerating the development of HDTV technology in North America, culminating in the development of the digital Grand Alliance HDTV System, the adopted standard. This paper summarizes the results of subjective image quality tests (Basic Received Quality, Impairment/Interference, and Receiver Scan Conversion) of the proponent HDTV systems from both rounds of testing, thereby permitting the reader to compare the relative performance of competing systems and gain some insight into the testing process conducted at ATEL.

Subjective evaluation of the digital HDTV grand Alliance system

Subjective evaluations of the digital high-definition television (HDTV) Grand Alliance System were performed by the Advanced Television Evaluation Laboratory of the Communications Research Centre in Ottawa, Ontario. The overall quality of the Grand Alliance System in both interlaced and progressive modes was examined. Additional tests were conducted to assess the ability of the system to co-exist with NTSC and to support scan conversion at the receiver. The system met or exceeded the specified requirements.

Source coding of wavelet-transformed digital HDTV for recording applications

A novel intraframe source-coding algorithm suitable for the recording of digital high-definition television signals is presented. A multilayered, hierarchical description of the source signal is obtained by means of a quad-tree, halfband wavelet transform. This transform decomposes the input signal into a collection of spectrally nonoverlapping sub-bands. These are used to influence the allocation of the available coding resources to the various layers, so that the integrity of visually significant features can be preserved. Individual sub-bands are quantised and entropy coded by using a predictive arithmetic coding technique. The algorithm is tuned to achieve bit-rate reduction ratios in the range 8 :1 - 4 :1 which is most useful for recording applications. Results obtained from simulating the coding algorithm show noticeable improvement over the current state-of-the-art international standard algorithm for still picture encoding, both in terms of subjective quality and of measured mean-square error.

The development of a high definition television (HDTV) terrestrial, broadcasting emission mask

This paper analyzes the case of HDTV channels, upper and lower, first adjacent to an existing NTSC station assignment and considers the interference from an HDTV adjacent channel, spillover spectra as undesirable co-channel interference into the NTSC channel. A subjective weighting function is developed for random noise interference to NTSC images at the video baseband level. A filter function representing the human visual system at specified viewing distances as a function of image height is developed, first for monochrome, and then extended to color images. The baseband subjective weighting function is modified to include the process of television canier modulation and demodulation. This carrier modified weighting function is then used to evaluate typical spillover spectra created by high power amplifiers when driven by a modulated digital HDTV signal. BTSC stereo audio (with SAP) is also included in the interference evaluation. Spectral out-of-band spillover limits are established based on the threshold of visibility of the interference as a function of the mileage separation between adjacent channel NTSC and HDTV stations. A high power bandpass filter and band elimination notches are included in the analysis. The results are then applied to two methods of determining spectral emission compliance: measurement of the out-of-band interference spectra with a weighting function, or alternatively, the use of an emission mask.

Research joint ventures and the development of digital HDTV

The National Cooperative Research Act of 1984 (NCRA) facilitated the creation of joint research and development ventures in the United States by diminishing the threat of antitrust litigation for selected cooperative research activities. This law enabled U.S. industry to move from a strictly competitive model to a more cooperative model in the development of new technologies, including those for electronic media. One of the early tests of this new cooperative model has been the formation of several high definition television (HDTV) research consortia. This study investigates the impact of the NCRA on advanced television research and development efforts in the U.S., and concludes with policy recommendations for future refinement of the cooperative research model.

Performance Simulation of COFDM for TV Broadcast Application

Following its successful implementation in digital data communications and digital audio broadcasting, coded orthogonal frequency division multiplexing (COFDM) has been proposed for potential digital television and high-definition television (HDTV) terrestrial broadcasting. This paper examines the potential performance of COFDM for digital television terrestrial broadcasting. An overview of OFDM principles is given, followed by discussion of the advanced television (ATV) channel model and system description. Case models are presented based on the North American broadcasting environment. To examine the performance of the system models, computer simulations were carried out. Analysis and observations based on these simulations are presented.

The Japanese scene [digital HDTV

Japan is the only country, so far, to be actually broadcasting high-definition television services. MUSE (multiple sub-Nyquist sampling encoding) is the basis for systems applying bandwidth compression to the transmission of both analog and digital signals. It encodes a signal of 1125 lines and 60 fields per second, a high-definition television (HDTV) signal into an 8-Hz bandwidth. Experimental MUSE broadcasts started in 1990 and have continued ever since. Meanwhile, work has been in progress in areas other than MUSE. Enhanced-definition television, a terrestrial system, is entering its second generation. Integrated digital broadcasting looks to spin many services into a single digital thread for transmission over a single channel. Digital sound broadcasting and hierarchical television transmission will also come in for consideration. The MUSE system depends on digital technology for signal processing, but the HDTV signal that is broadcast is analog, the outcome of frequency modulation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The US HDTV standard

This standard for digital high-definition television has been submitted to the Federal Communications Commission for its approval. Based as it is on the MPEG-2 video compression and transport protocol, multiple transmission formats, Dolby AC-3 digital audio, and vestigial sideband digital modulation, this HDTV system will supply the home with superb images and spectacular sound while also, as part of the National Information Infrastructure (NII), relaying digital data. An HDTV system employing multiple transmission formats, digital compression, packetization, and modulation techniques is a marked advance over current world television standards such as NTSC, PAL, or SECAM.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Proposed Computer-Controlled Digital HDTV Chroma-Key System

Picture quality utilizing the soft chroma-key method is influenced by the degradation on the edge area between the foreground image and the background image. A new technique is proposed to subtract chroma-key blue while considering the distribution of chrominance on the edge area. A new high-definition television (HDTV) digital chroma-key system using this method is described.

The Grand Alliance HDTV video encoder

Members of the digital high definition television (HDTV) Grand Alliance have jointly designed and constructed a high definition video encoder as part of an overall HDTV broadcast system. The encoder accepts video in either 1080 line (30 Hz) interlaced format or 720 line (60 Hz) progressive format, and produces a bitstream compliant with the Motion Picture Experts Group version 2 (MPEG-2) standard. The encoder processing includes large-area motion estimation, adaptive telecine processing, and an advanced rate control mechanism. The paper describes the hardware architecture and implementation trade-offs of this encoder.

HD-SAT modems for the satellite broadcasting in the 20 GHz frequency band

This paper introduces the HD-SAT project and describes the two satellite modems designed for high definition digital television broadcasting by satellite in the 20 GHz frequency band. The graceful degradation satellite modem uses layered modulation (TCM-8PSK/QPSK) to increase service continuity in this rain-attenuation sensitive band. The 45-70 Mb/s TCM-8PSK modem demonstrates the feasibility of domestic variable rate receivers by using digital demodulation techniques suitable for very highly integrated implementations. Together these modems, both of which have been the subject of prototype demonstration and tests, address the essential functional and implementation issues of the Ka band for digital HDTV broadcasting.

An HDTV Digital Camera Processor

This article describes a fully digital high-definition television (HDTV) camera processor. The experimental processor was developed as part of a continuing effort to investigate digital video processing for HDTV. Since digital conversion is done close to the imager in the processing chain, the implementation of camera processes is accurately calculated, stable, and easily adjusted for user preferences. Much of the processing calculation is accomplished in software using an embedded controller. Nonlinear transfer curves such as gamma correction and dynamic “knees” are implemented in continuous curves instead of the usual linear piecewise approximations. Early digitization also allows more sophisticated shading and color balance. In addition, a novel adaptive enhancement automatically selects contours to improve color detail in scene areas that are not predominantly green.

European HDTV Strategy: Muddling Through or Muddling Up?

Following a successful technology R&amp;D programme, the European High Definition Television (HDTV) system was the only one available. Despite this, it will never reach the market. In June 1993 the great strategy of the EC to conquer the world with its own transmission system was officially abandoned. This article examines the strategy and the policy-making process that aspired to promote the European model of HDTV but failed. It argues that divergent and conflicting national and industrial interests, as well as divergent policy approaches, are in part to blame for this failure. Mismanagement of time in the policy process due to these conflicting approaches and interests was fatal as concurrently swift technological innovations led to the development of the competing digital HDTV model. It further argues that policy making was not flexible enough — and therefore not incremental — and that it ignored factors such as consumer demand. The HDTV strategy and policy goals were unrealistic and incongruent with available means as, for example, those who sought subsidies for the production of HD-MAC were concurrently developing the antagonistic digital model.

Point of View: A Migration Path to a Better Digital Television System

It is generally accepted that the resolution goal for a new high-definition television (HDTV) system is to transmit over the air more than 1000 lines with progressive scanning at 60 frames/sec within one single 6-MHz channel. The currently available transmission and video compression technologies do not appear to support such a high video resolution. As a result, the transmission formats currently being considered for the digital HDTV standard are at a lower spatial resolution and/or at a lower frame rate than the resolution goal. This article addresses the question of how future developments in the video compression technology can be incorporated to migrate towards the resolution goal in a receiver-compatible manner. The approach that we propose is to use enhancement data that can be combined with the standard video data. As new video compression technologies are developed, the number of bits needed to support the standard transmission formats will decrease and the channel capacity released can be used to encode the enhancement data. The standard HDTV receivers will utilize the standard video data, ignoring the enhancement data. More advanced HDTV receivers will combine the enhancement data with the standard video data to migrate to the desired resolution goal.

Possible channel coding and modulation system for the satellite broadcasting of a high-definition television signal

A new coding/modulation approach is considered to improve service availability of digital high-definition television (HDTV) satellite broadcasting services at 22 GHz. This approach uses a concept of layered modulation in conjunction with layered picture coding and channel coding. By means of this technique, the service continuity can be extended without the needs for increasing the satellite transmission power, the service quality under severe atmospheric attenuations being reduced from high definition to normal definition.

Measuring peak/average power ratio of the Zenith/AT&amp;T DSC-HDTV signal with a vector signal analyzer

The different power measurement techniques used for NTSC (peak envelope power) and HDTV (average power and peak-to-average power ratio) are described. A brief description of a digital data transmission system is included to show why the HDTV signal is noiselike in nature and how it can be measured. A new type of RF analyzer with the ability to statistically measure peak-to-average power ratio is presented. The Zenith/AT&T digital spectrum compatible high definition television (DSC-HDTV) data transmission system is currently one of the systems being evaluated for the consideration as a US broadcast standard. Examples of signal measurement for this system are provided. >

Possible coding and modulation approaches to improve service availability for digital HDTV satellite broadcasting at 22 GHz

Novel coding/modulation approaches for improving the service availability of digital HDTV (high-definition television) satellite broadcasting services at 22 GHz are considered. Two possible approaches are described which use the concept of layered modulation in conjunction with layered picture coding and channel coding. By means of this technique, the service continuity can be extended without the needs to increase the satellite transmitted power, the service quality under severe atmospheric attenuations being reduced from high definition to normal definition. Most of the time, e.g., for up to 99% of the worst month, the service provides nominal HDTV quality, while during heavy rain fades the receiver decodes the normal TV picture. >

Advanced digital HDTV transmission system for terrestrial video simulcasting

Transmission aspects of the advanced digital high definition television (AD-HDTV) system, for terrestrial simulcast delivery of HDTV are described. In AD-HDTV, two quadrature-amplitude-modulated (QAM) carriers, with different power spectral densities, are employed in a frequency division multiplex (FDM) mode within the standard 6-MHz channel. The resulting spectral shaping allows a larger power to be transmitted, compared to that for a single QAM carrier, for the same level of perceptual interference into cochannel NTSC. The coded video data are split into high-priority (HP) data and standard-priority (SP) data, and the vital information is sent on the appropriate QAM carrier, resulting in a robust audio and video transmission system. The availability is higher in scenarios where the carrier-to-noise ratio (CNR) is above the threshold for HP reception but below the threshold for SP reception; this is important in fringe areas. The NTSC planning factors, suitably modified for HDTV delivery, are used to estimate the coverage area for AD-HDTV. The calculated AD-HDTV coverage area of 54.5 miles is comparable to that for NTSC transmission.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Performance analysis of the advanced digital HDTV video coding system

Advanced digital high definition television (AD-HDTV) is an all-digital simulcast system designed to provide high-quality HDTV service to a large coverage area through a single 6 MHz terrestrial broadcast 'taboo' channel. The paper describes the technical details of the AD-HDTV video coding system and provides an analysis of the system performance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>