Readback circuit for an optical information reading and recordin

Details Readback circuit for an optical information reading and recordin Readback circuit for an optical information reading and recordin

1995-12-05

1997-10-07

Ben, Loha

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

369 59, 360 51, 371 30, 371 43, 371 55, 341107, 341 59, 341 94, G11B 700

Patent

active

056755694

ABSTRACT:
A recorded signal reproduction circuit in an optical disc information reading and recording apparatus converts a recorded signal recovered from an optical disc to PR (1, 2, 1) characteristics through a equalizer circuit, digitizes it through an A/D converter and at the same time also generates a clock signal synchronized in phase with the equalizer circuit output signal by using a binary edcoder circuit and a PLL circuit. This clock signal is then provided to an A/D converter as the sampling clock. The A/D converter output signal is then decoded to the original channel bit stream based on the clock signal. Because the equalizer circuit output signal is provided to both the binary encoder/PLL circuit and the A/D converter together, additional circuity for converting signals into a binary series of pulses is unnecessary and reduction of circuit scale is possible. Moreover, in case of a change-over in the frequency characteristics of the equalizer circuit, due to a change in recording and reproduction frequency, the change-over will not affect the phase relationship between an input signal to the A/D converter and a sampling clock. In addition, it becomes simple to adjust this phase relation.

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patent: 5517476 (1996-05-01), Hayashi
Ogami et al, "Optical Disc Technique", Radio-Gijutsusha, Feb. 10, 1989, pp. 188-191.
Kitahara et al, "Performance of Viterbi Decording System for 1,7 Code in Magneto-Optical Recording", Report No. C-472 of Japan Electronical Information and Communication Institute in 1993 Spring Meeting, pp. 5-102.
"New Detector for 1,k Codes Equalized to Class II Partial Response" (Roger Wood, IEEE Transactions on Magnetics, vol. 25, No. 5, Sep. 1989, pp. 4075-4080).
"Partial Response Signaling" (Peter Kabal et al. IEEE Transactions on Communications, vol. Com-23, No. 9, Sep. 1975, pp. 921-934).
"Viterbi Detection of Class VI Partial Response on a Magnetic Recording Channel" (Roger W. Wood et al. IEEE Transactions on Communications, vol. Com-34, No. 5, May 1986, pp. 454-461).

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