Seiichi Mita

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.

Concatenated error correction coding for high-order PRML channels

A modified E/sup 2/PRML (ME/sup 2/PRML) channel is optimized for high-density magnetic recording in order to reduce long error-propagation events in an ML detector. A cyclic redundancy-check error-correction code (CRCC), an innerblock ECC concatenated to the ML detector, is introduced as a new ECC-coding scheme for the high-order partial response maximum likelihood (PRML) channel. The CRCC coding can efficiently improve the BER performance with only a few redundant check-bits which intensively correct most-dominant short error-events in the ME/sup 2/PRML detector. A 16/17 coded ME/sup 2/PRML channel in conjunction with a 2.9% redundant CRCC coding can achieve a gain of more than 35 dB over a conventional 16/17 coded EPRML channel at a user density of 2.8.

Turbo-EEPRML: An EEPR4 channel with an error-correcting post-processor designed for 16/17 rate quasi-MTR code

An EEPRML channel with a post processor has been developed for compensating for the degradation in performance due to noise correlation. This Turbo-EEPRML is designed for 16/17 rate quasi-MTR (QMTR) code. The proposed method has high performance and simple circuitry. Simulation showed that Turbo-EEPRML has a 2.0-2.5 dB coding gain over a conventional EPRML channel for 16/17 GCR code.

Write control method for high density magneto-optical disk system

In order to increase recording density, mark length recording is superior to mark position recording. However, in the case of magnetooptical media it is difficult to control mark edge position and shape because of its higher thermal conductivity. A new write control method using the multiple pulse write waveform is proposed, and it is shown that high density of 880 Mb/in/sup 2/ can be realized using this write control method. >

A 150 Mb/s PRML chip for magnetic disk drives

Recent magnetic disk drives require high transfer rates and recording densities. PRML signaling is now prevalent in digital read/write channels. This PRML chip operates at a maximum data rate of 150 Mb/s with 1550 mW and includes all basic functions such as servo demodulation and write pre-compensation for magnetic disk drives with optimized circuit size. The chip is fabricated in 0.7 /spl mu/m double-poly double-metal BICMOS suitable for low-power devices and is packed in a 100-pin quad flat package with a die approximately 7 mm/sup 2/. This chip has a single 5 V power supply.

Characterization of digital recording channels by means of echo cancellation techniques

A simple yet accurate method is described for characterizing digital recording channels in terms of linear and nonlinear intersymbol interference and noise. The method is based on echo cancellation techniques, enables recorder operating conditions close to actual use, and delivers a joint portrait of the disturbances rather than isolated assessments. Experimental results for a high-density digital video tape recorder are included. >

Digital Video Recording Techniques Using 1/2 Inch Metal Particle Tape

During the past ten years, rapid progress has been made in development of recording techniques for home use VTR. Nevertheless, a limit has now been reaches to improvement in such functional areas as SN ratio, resolution, and dubbing. It is now expected that digital recording techniques will be introduced into the video field in the future to assure even further development.

Precise Mark Shape Control in Mark Length Recording on Magnetooptical Disk

To realize higher storage density on a magnetooptical disk, we proposed the write control method, which controls shapes of recorded mark in marks length recording. In this paper, the analysis of this write control method is reported. Based on the model of the recording process, we discuss the necessary condition of the recording pulse waveform for the control of the recorded mark shape on magnetooptical recording media which have large heat conductivity. The write control method is examined under the condition of 880 Mb/in2 recording density. The precise control of the recording mark shape is confirmed through the experiment. From the result of the computer simulation, it is proven that this method satisfies the necessary condition, which clarified the effect of this method theoretically.

Soft-output post-processing detection for PRML channels in the presence of data-dependent media noise

A soft-output data-detection scheme optimized for data-dependent media-noise recording channels is proposed that uses signal-dependent correlation-sensitive (SDCS) metric estimation for post-processing decoding. This media-noise soft-output (MNS) decoding scheme achieves sub-optimal maximum-likelihood (ML) sequence detection in a non-stationary media-noise channel, while still using traditional Viterbi detection. Because it drastically reduces SDCS metric computation by focusing on only specified dominant error-events in the ML detector, it is less complex than other sub-optimal detection schemes. Moreover, its one-shot post-processing scheme enables the use of a simple lookup-table architecture suitable for high-speed circuit implementation. Simulation shows that the MNS decoding scheme in conjunction with a conventional ME/sup 2/PRML system provides an excellent tradeoff between data-detection performance and computation complexity for a media-noise-dominant high-density recording channel.

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.