Achievements in rotary head magnetic recording

The principal achievements since 1980 in rotary head recording on magnetic tape are outlined. These developments are related to fundamental improvements in recording media, heads, the design of tape transports, and signal processing. The D-1 and D-2 video tape recorders (VTRs), the Hi-Band 8-mm video cassette recorder (VCR), and the rotary digital audio tape (R-DAT) recorders are discussed. The future of rotary head recorders for consumer digital VCRs, professional high-definition TV (HDTV) VTRs, and consumer HDTV VCRs is assessed     

FLC and VLC coding for professional digital HDTV recording — Application to D1-like recorders

Digital recording is a key issue for HDTV studio applications. However, digital baseband recording of HDTV has some drawbacks, for example, high tape consumption and the fact that 1.2 Gbit/s recorders are close to technology limits. Bit-rate reduction techniques allow these difficulties to be overcome. This paper deals with two different approaches for picture coding suitable for professional HDTV recording, with special attention paid to compatibility with existing D1 VCRs (video cassettes recorder). The first approach considers that the behavior of a recorder requires FLC (fixed length code) data as opposed to VLC (variable length code) data, and the second approach supposes that the problems generated by use of VLC data can be overcome with preanalysis and extra error protection strategies. Comparisons of efficiency are presented including multiple copying.     

几种主流数字磁带录像机的分析比较

随着信息技术的发展,数字录像机凭借其优越的性能和适中的价格而得到广泛的应用,针对目前数字磁带录像机种类繁多的情况,讨论几种主流的不同类型不同记录格式机型的性能差别,为中小电视台选购录像机提供参考。     

Signal processing for future home-use digital VTR's

The author considers, mainly from the viewpoint of signal processing technologies, the current efforts for future home-use digital videotape recorders (VTRs). Recording technologies for future home-use digital VTRs are reviewed with respect to both current TV and HDTV systems. High-density recording and bit rate reduction are the major technologies needed for digital video recording with small cassettes. Recent experiments show that the technical problems, except those of equipment size and cost, have almost been solved     

Unrecordable Video

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.     

株洲台基于双链路架构的高清播出技术建设方案

随着广播电视技术与计算机网络技术的融合发展,录像机和节目制作的高清普及,数字化高清播出已经成为当今电视发展的新阶段。如何搭建一个安全、高效、管控性强的高清播出系统已经变得尤为重要。     

MAV-555A在数字电视转播车中的应用

主要介绍了MAV-555A硬盘录像机的特点及其在数字转播车中的多种应用。电视转播车通过使用MAV-555A硬盘录像机在拓展了电视转播车功能的同时,也大大提高了电视节目转播及录制等方面的安全性,使电视转播车更能适应现代电视节目制作的要求。     

Applications '90: consumer electronics

Significant developments during 1989 are reviewed. In television, testing of a number of high-definition television (HDTV) systems began, work on ghost cancellers continued, and new entries intensified competition in large-screen displays. Videodisc players started to make a comeback, and still video cameras for consumers were introduced. The long-delayed marketing of digital audio tape (DAT) recorders in the US moved closer to reality in June when a joint recommendation setting up copyright protection guidelines was drawn up by leaders of the international recording and consumer electronics industries     

Some general methods for tampering with watermarks

Watermarks allow embedded signals to be extracted from audio and video content for a variety of purposes. One application is for copyright control, where it is envisaged that digital video recorders will not permit the recording of content that is watermarked as “never copy”. In such a scenario, it is important that the watermark survive both normal signal transformations and attempts to remove the watermark so that an illegal copy can be made. We discuss to what extent a watermark can be resistant to tampering and describe a variety of possible attacks     

A 10-bit 20-MHz two-step parallel A/D converter with internal S/H

A 10-bit 20-MHz A/D converter for high-quality video systems such as high-definition television, video tape recorders for business use, and digital video cameras is described. This LSI circuit uses a standard two-step parallel architecture, includes automatic gain adjustment and digital two-bit error correction, and has a sample-and-hold circuit on the chip. It is fabricated by a 4.5-GHz f_T. 3-μm-rule standard bipolar technology. Its die size is 25 mm² , and its power consumption is 900 mW, which is about half of the lowest values reported to date. The converter can digitize video signals of up to 8.5 MHz at a conversion frequency of 20 MHz. The error in differential gain is 0.5 percent, and the error in differential phase is 0.5°     

Digital video interfacing: a practical solution

Broadcast video technology has begun to shed its analogue history and take on board the benefits of the digital era. Areas such as digital video recording and processing have been addressed. However, the means of conveying digital video information from one device to another have been cumbersome and expensive. The author describes how these problems have been overcome. It describes the limitations of the current method and provides an overview of a new, serial, interface. Details and benefits of the new interface are given and new integrated circuits to implement the interface are also described. Consideration is given to installation, test and measurement     

Digital recording in the professional industry. 1. Recordingtechnology

Describes the use of digital techniques in professional sound recording. It outlines the processes of sampling, quantising and channel coding necessary for converting an analogue signal into a digital format suitable for recording on magnetic tape, as well as the signal reconstruction processes are outlined. Popular stationary and rotary head recording formats are described     

录象机重放图象信号噪波的分析与测量

本文介绍了录象机噪波理论分析和用频谱仪测量噪波的方法,对专业作者有一定的参考价值。     

Particulate recording materials

Information (audio, video, or data) to be recorded magnetically is first encoded into a sequence of time-varying electrical signals which are used to drive a writing head, the magnetic field of which creates, on the moving tape or disk, a spatially varying pattern of magnetization. The reading process uses another head (or the same head) to reconvert this magnetization pattern into time-varying electrical signals that can be amplified and used to drive a loudspeaker, or a TV receiver, or feed data to a computer. Two methods of encoding the information are used; analog and digital. In analog recording, as the adjective suggests, the pattern of magnetization on the recording medium should be a precise analog of the incoming stream of information and the signal obtained on reading should be an exact reproduction of the original. Digital recording involves first converting the information into a sequence of ones and zeros which can then be recorded as a sequence of regions of opposite magnetization. Analog recording has been widely used to store audio and video information while digital recording was used for data recording. This picture is changing and digital recording is now being used increasingly in audio and video recording principally because errors can be corrected dynamically so that the original information can be reconstructed and copied repeatedly and with great fidelity. Whether the recording method used is analog or digital, similar though not identical properties are required of the recording materials and so the distinction between the two methods will not be pursued further.     

Tutorial review of magnetic recording

Most of the technologically important aspects of magnetic recording are reviewed in a nonmathematical manner. After a discussion of recording media and heads, the fundamentals of the media magnetization and writing processes are considered. The factors limiting the bandwidth, distortion, and signal-to-noise ratio of audio, instrumentation, video, and digital recording machines are analyzed. The paper concludes with some predictions on the future of magnetic recording.     

A new video hard disk system for multimedia program production

This paper reports on a new video hard disk system for real-time recording and playing back of high-quality digital video signals, an important component in the production of multimedia programs at broadcasting stations. The paper clarifies some of the problems associated with the recording of high-quality video signals on a conventional hard disk system designed for storing computer data. It describes the requirements of a future video hard disk system. We have developed an experimental high-speed hard disk interface device suitable for transferring video signals. This device can guarantee continuous transfer of video signals with a high bit rate, sending them at 123 Mbps/ch-more than twice as fast as a conventional device. Using this interface, we have developed a video hard disk system capable of real-time recording and playing back of non-compressed video signals (conventional TV)     

Codes for digital recorders

Constrained codes are a key component in digital recording devices that have become ubiquitous in computer data storage and electronic entertainment applications. This paper surveys the theory and practice of constrained coding, tracing the evolution of the subject from its origins in Shannon's classic 1948 paper to present-day applications in high-density digital recorders. Open problems and future research directions are also addressed     

Partial-response coding, maximum-likelihood decoding: capitalizing on the analogy between communication and recording - [History of communications]

Signal processing and coding technology for digital magnetic recording is the core technology of the channel electronics module in a hard disk drive (HDD) that processes signals read from magnetic media. In this historical review I focus on what is now widely known as partial-response, maximum-likelihood (PRML) technology, which takes advantage of the inherent redundancy that exists in signals read out of magnetic media; its theoretical foundation goes back to 1970, and it capitalizes on the analogy between high-speed data transmission and high-density digital recording, and that between a convolutional code and a partial-response signal. The first PRML-based product was introduced by IBM in 1990, and PRML technology soon became the industry standard for all digital magnetic recording products, ranging from computers' HDDs and tape drives to micro hard discs used in PCs, mobile phones, and MP3 players; use of the PRML principle has recently been extended to optical recording products such as CDs and DVDs. Its improved version, called NPML (noise-predictive, maximum-likelihood), and variants have been adopted by the HDD industry since 2000. Today, a large number of communication and information theory researchers are investigating use of advanced techniques such as turbo coding/decoding to further improve the density and reliability of both magnetic and optical recording systems.     

An error-correction scheme for a helical-scan magnetic data storagesystem

An error-correction scheme for a helical-scan magnetic recording system is presented. The system consists of a commercial VHS video cassette recorder with the front-end electronics adapted for high-speed digital recording. Error statistics have been collected and show a bursty error recording channel both within each track and from track-to-track. The proposed error-correction scheme uses interleaved Reed-Solomon codes. The interleaving function consists of a two-level interleaver performing track interleaving and byte interleaving. An efficient interleaving implementation is presented