Matsushita Graphic Communication Systems, Inc.

Matsushita Electric Industrial Co., Ltd.

Panasonic Communications Co., Ltd.

Eizo Katayama

Genzo Takagi

Mitsuhiro Araki

Nobuhiko Noma

Mikio Mizutani

Yoshihiro Noguchi

Yoshihiko Noguchi

Motoyasu Ohno

Keiji Ueki

Yoshinori Takahashi

Tsukasa Kanazawa

Shinji Hasunuma

Kazuo Suzuki

Kaname Sawada

A MODEM can shorten the processing time of an interface disposed between a data terminal equipment (DTE) and the MODEM. The MODEM stores an object program of a procedure in a memory and switches an operational mode of the MODEM automatically corresponding to the prescribed procedure thereby executing the procedure corresponding to the current operational mode. The MODEM further comprises a timer which monitors the transits time between a completed procedure and the next procedure, and the MODEM starts the process of a specified operational mode based on a mode-setting-instruction of the procedure as well as monitoring the transitions time by using the timer, and executing a next specified operational mode when the timer times out, thereby allowing the MODEM to perform the various operational mode switches.

Modulator and demodulator (MODEM)

A digital signal detection circuit includes a threshold value calculator calculating a threshold value from assumptive sampled values corresponding to various data patterns of a regenerated signal. The regenerated signal is obtained by regenerating data recorded on a recording medium by a regenerating head. The detection circuit also includes a Viterbi decoder carrying out Viterbi decoding of the regenerated signal with the threshold value determined by the threshold value calculator as a constant. The threshold value calculator variably controls the threshold value using a decoded output of the Viterbi decoder and a regenerated signal corresponding to the decoded output of the Viterbi decoder.

Digital signal detection circuit

An optical disc is subdivided into a plurality of concentric tracks. The tracks are further subdivided into a plurality of sectors. A method for recording data on such an optical disc includes the steps of designating some of the sectors as preliminary sectors and the remaining sectors as user sectors, identifying defective user sectors, and recording data corresponding to the defective sectors on the preliminary sectors.

Method for recording data on non-defective sectors of an optical disk

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Yokohama, Japan

Eizo Katayama