Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Patent
1982-10-13
1985-09-03
Richardson, Robert L.
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
369 59, 369240, G11B 2300, G11B 2710, G11B 700
Patent
active
045396663
ABSTRACT:
Apparatus for reproducing from a record disc a run length limited PCM audio signal comprises an optical transducer which reproduces the PCM audio signal from the record disc; a waveform shaping circuit for producing an output signal corresponding to the reproduced PCM audio signal and having portions of opposite polarities so that the output signal includes a plurality of transition intervals; a clock pulse generator for generating clock pulses having a constant frequency higher than the bit frequency of the output signal; a counter for detecting the period of each transition interval of the output signal by counting the number of clock pulses generated during each detected transition interval of the output signal; a NAND gate for determining, during each of at least one predetermined period selected to be longer than the period ##EQU1## if the number of the clock pulses counted by the counter during each detected transition interval in each longer predetermined period corresponds to a predetermined number of clock pulses included in the maximum transition interval which occurs when the record disc is rotating at a predetermined constant linear velocity, and for producing a velocity control signal in response thereto; and a drive circuit for controlling rotation of the record disc at the predetermined constant linear velocity in response to the velocity control signal.
REFERENCES:
patent: 4397011 (1983-08-01), Ogawa
T. T. Doi, "General Information on a Compact Digital Audio Disc", J. Audio Eng. Soc., vol. 29, No. 1/2, 1981, Jan./Feb., pp. 60-66.
Doi et al., "A Long Play Digital Audio Disc System", J. Audio Eng. Soc., vol. 27, No. 12, [Dec. 1979], pp. 975-981.
Eslinger Lewis H.
Richardson Robert L.
Sinderbrand Alvin
Sony Corporation
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