Yoshizumi Eto

Automatic equalizer for digital magnetic recording systems

This paper describes a new adaptive automatic equalizer based on both Linear Cancellation and probablistic decoding techniques for eliminating Intersymbol Interference in digital magnetic recording systems. It is confirmed that sufficient eye opening and error rate improvements can be achieved using this equalizer at an operation speed of 46 Mbps.

Digital video recording

Through mutual technology transfer between consumer and professional video recorders, the last 20 years has witnessed a rapid evolution from analog to digital recording. Each new digital videotape recorder (VTR) uses different channel coding. This implies that improving the recording density involves the development of new channel-coding schemes together with evolutionary magnetic tapes and heads. As a result, professional digital VTRs offer the best features for video recording. This paper reviews state-of-the-art magnetic recording devices, signal processing techniques for digital recording. It also describes the specifications for home-use digital recorders for current television systems, and discusses disk recording technology in the future. >

High data rate recording for HDTV digital VTR

A metal-particle tape and sputtered amorphous-on-ferrite (SAF) head with a lamination structure are examined at 150 Mb/s. The C/N of 31 dB achieved at this high bit rate ensures a word error rate of less than 5*10/sup -5/. It is shown to be feasible to record at a bit rate of 180 Mb/s (135 kb/cm). Flying AC erase using an SAF head at a frequency lower than half of the bit frequency is effective for this type of high-data-rate recorder. These recording techniques establish the fundamental feasibility of digital video tape recorders for high-definition TV at 1.2 Gb/s. >

Adaptive DCT coding for home digital VTR

The authors investigate fixed adaptive discrete cosine transform (FADCT) coding for use in digital VTRs (video tape recorders). The image is divided into 8*8-pixel subblocks, and a two-dimensional DCT is performed on each of them. The quantization scheme is adapted to input image data, thereby increasing coding efficiency. The scheme is designed, however, to keep the output data rate fixed. Computer simulation showed that FADCT coding improves the SNR (signal/noise ratio) from 1 dB to 3 dB as compared to nonadaptive DCT coding, and a high-quality image with SNR over 40 dB can be obtained at 3 bits/pixel. Reallocations of the extra bits from the higher to the lower AC energy subblocks allow the application of adaptive coding to the digital VTR, with a high tolerance for channel errors.<<ETX>>

Experimental Digital VTR with Trilevel Recording and Fire Code Error Correction

This paper describes an experimental digital videotape recorder that uses trilevel magnetic recording and improved Fire-code error-correction techniques. The S/N ratio obtained was almost the same as that obtained with the conventional NRZ method. The VTR that has been demonstrated records in two magnetic channels at the same rate of tape consumption as an analog VTR. The optimum tape format is under investigation.

Facsimile Signal Decoding Which Localizes the Effect of Run-Length Code Errors

A new run-length decoding method for facsimile signal transmission is described. In this method, if an error code is detected in a received signal, the effect is localized in the runs corresponding to the error instead of the whole line to obtain better picture quality. The error immunity in this method can be used to shorten the transmission time.

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. >

A Totally Digital Camera System Using Digital Triaxial Transmission

A fully digital broadcast camera system has been developed at Hitachi, in which all signal processing and transmission are accomplished in the digital domain. The newly developed digital transmission for this system utilizes time division multiplexing and video compression to provide bidirectional serial digital transmission over standard triaxial cable. These compression methods allow all video, audio, and control signals between the camera head and the camera control unit (CCU) to be combined into a single bidirectional 360 Mbit/sec serial digital signal for transmission. At the CCU, the received digital video signals are digitally rate converted into either an SMPTE 259M composite digital output or a SMPTE 259M component digital output for direct interface to digital studio equipment.

1.2 Gbit/s HDTV digital VTR

Abstract Some of the essential features of the record/playback system of a new 1.2 Gbit/s digital VTR are described. The VTR can record the full bandwidth of 1125/60 HDTV signals, namely 30 MHz luminance, and 15 MHz for each of the two color difference signals. As for low error rate recording techniques, a cross-shape multilayered amorphous head, a 5 stage transversal filter, a playback head with a narrow trackwidth and a special PLL to cope with stunt motion are employed. At a high data rate of 148.5 Mbit/s and a high linear density of 0.345 μm per bit, the recorder confirms reliable operation with a word error rate of less than 10 −4 .

An Experimental 648 Mbits/s HDTV Digital VTR

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.