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Apparatus for recording an audio signal with protection against re-recording thereof, and recording apparatus which indicates the presence of such protection

  • US 5,083,224 A
  • Filed: 03/15/1990
  • Issued: 01/21/1992
  • Est. Priority Date: 04/14/1989
  • Status: Expired due to Fees
First Claim
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1. Apparatus for recording on a record carrier an audio signal comprising a left-hand and a right-hand channel, which apparatus has a first and a second input terminal for receiving the left-hand and the right-hand channel respectively, said first and said second input terminal being coupled respectively to a first and a second input respectively of the recording unit to record the signals applied to its inputs on the record carrier;

  • characterized in that;

    the first and the second input terminal are coupled to an input of a first and a second filter respectively, which filters are adapted to extract a first and a second low-frequency signal component from the left-hand and the right-hand channel respectively and to apply the first and the second low-frequency signal component to an output;

    the output of the first filter is coupled to an input of a first signal-processing unit and the output of the second filter is coupled to an input of the second signal-processing unit;

    the outputs of the first and the second signal-processing unit are coupled to the first input and the second input respetively of the recording unit;

    the first signal-processing unit is adapted to add a first auxiliary signal to the signal applied to its input and to supply the signal thus processed to its output, and the second signal-processing unit is adapted to add a second auxiliary signal to the signal applied to its input and to supply the signal thus processed to its output; and

    the first and second auxiliary signals being such that during reproduction of the audio signal, including the first and the second auxiliary signal added thereto, via two loudspeaker units arranged in a stereo configuration, the auxiliary signals are substantially inaudible to a listener.

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