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Data access arrangement with telephone interface

  • US 5,790,656 A
  • Filed: 09/29/1995
  • Issued: 08/04/1998
  • Est. Priority Date: 09/29/1995
  • Status: Expired due to Term
First Claim
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1. A data access arrangement (DAA) for coupling a local modem to a local telephone set across a single telephone line, in communication with a central office line, wherein the modem responds to signals received across the telephone set, the DAA being operable with program means for controlling communication between the modem and the telephone set, and for directing the modem to process the incoming signals received across the single telephone line through the telephone set, and for controlling the connection of the telephone set to the central office line, such that the single telephone line enables transmission of voice and data signals the DAA comprising:

  • a current source adaptively coupled to the telephone set, the current source including;

    a current regulator for providing a constant current to the telephone set when the telephone set is disconnected from the central office line, wherein a variable voltage is produced across the telephone set which varies according to the signals received across the telephone set, the current regulator operable with an input voltage, anda voltage reference circuit coupled to the current regulator, for enhancing the input voltage supplied to the telephone set; and

    a voice relay for switching the connection of the telephone set between the central office line and the voltage regulator and voltage reference assembly in response to the program means, wherein for the modem and telephone set to communicate directly with each other independent of the central office line, the program means causes the relay to connect the telephone set to the voltage regulator and voltage reference assembly, thereby disconnecting the telephone set from the central office line.

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