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Adaptive telephone receive control

  • US 4,831,650 A
  • Filed: 05/16/1988
  • Issued: 05/16/1989
  • Est. Priority Date: 05/16/1988
  • Status: Expired due to Fees
First Claim
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1. A pay telephone system comprising:

  • a telephone signal circuit having an electrical output;

    a telephone receiver having an electrical input and an acoustical output;

    an amplifier having at least one signal input and an output, said output coupled to said electrical input of said telephone receiver;

    a binary controlled crosspoint switch having a first set of electrical terminals, a second set of electrical terminals, and switching means responsive to binary input signals for selectively interconnecting one of said first set of terminals to one of said second set of terminals as a function of a binary input number; and

    attenuation means for placing selected attenuation in circuit between said electrical output of said signal circuit and said receiver comprising;

    first attenuation means coupled in circuit with said electrical output and said first set of electrical terminals for effecting a discrete factor of attenuation of signals at each said terminal of said first set of terminals, andsecond attenuation means coupled between said second set of terminals and to said signal input of said amplifier for effecting a discrete factor of attenuation at a discrete one of said second set of terminals;

    condition sensing means responsive to the signal state of signals present in said electrical output of said signal circuit for providing a plurality of discrete outputs as functions of said last-named signals; and

    a control system responsive to selected discrete outputs of said condition sensing means for providing a discrete binary input signal to said crosspoint switch for selectively effecting the switching of said input terminals to said output terminals and thereby effecting a selected change in level between said electrical output of said signal circuit and said telephone receiver.

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