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Apparatus for recording a digital information signal and utilizing the digital sum value thereof to record an auxiliary digital signal, and apparatus for reproducing such recorded signals

  • US 5,136,436 A
  • Filed: 04/13/1989
  • Issued: 08/04/1992
  • Est. Priority Date: 04/26/1988
  • Status: Expired due to Fees
First Claim
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1. Apparatus for recording a digital information signal and an auxiliary digital signal in information tracks of a record carrier and, prior to recording, converting successive information words of the digital information signal into selected channel words;

  • said apparatus comprising;

    a signal generator for producing a signal (RV) representing the digital sum value (DSV) of said auxiliary signal;

    an encoding device having an input for receiving the successive information words and which is adapted to convert each information word into a selected channel word of a channel code such that at least three channel words of mutually different disparities are available for each of the information words, and to supply the selected channel word to an output of the apparatus;

    a control signal unit for receiving said signal (RV) from the signal generator and the channel words produced by said encoding device, and adapted to supply a control signal to said encoding device which controls it to select channel words such that the digital sum value (DSV) of the channel words which are recorded varies substantially in accordance with variations of said auxiliary signal;

    the control signal unit comprising an integrating circuit for deriving the digital sum value (DSV) of the channel words which are recorded and a signal-combination unit which is adapted to derive said control signal from the difference between said digital sum value (DSV) and said (RV) signal; and

    feedback means connected to the output of said apparatus for deriving from the channel words produced at said output a further control signal for said encoding device;

    said further control signal including, for each channel word, at least the last bit of the immediately preceding channel word;

    said encoding device being adapted to select a channel word for the information word at its input depending on said first-named control signal and said further control signal.

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