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Adaptive delta modulation system

  • US 4,208,740 A
  • Filed: 12/20/1978
  • Issued: 06/17/1980
  • Est. Priority Date: 12/20/1978
  • Status: Expired due to Term
First Claim
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1. In a delta modulation system including an analog input connected to a first input of an analog signal compare means whose output in turn is connected to a periodic sampling means generating a delta modulated signal di at a sampling frequency which is provided to a system output and to the input of a companding means whose companded signal output α

  • i is connected through an integrating network means to a reconstructed analog signal input, wherein said companding means further comprises;

    a digital switching circuit for calculating
    
    
    space="preserve" listing-type="equation">α

    .sub.i ={(C-B)α

    .sub.i-1 } when d.sub.i ≠

    d.sub.i-1,
    
    
    space="preserve" listing-type="equation">α

    .sub.i ={(A+C)α

    .sub.i-1 } when d.sub.i =d.sub.i-1, and ##EQU3##
    
    
    space="preserve" listing-type="equation">when d.sub.i =d.sub.i-1 =. . . =d.sub.o for i>

    2 whereA, B, C are positive constants less than unityA+C >

    unityC-B<

    unity, andα

    i for i=0 is the minimum step size generated by said companding means;

    whereby rapid adaptive digital companding of the delta modulation signal fed back via said integrating network to said compare means is achieved.

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