Patents by Inventor Charles F. Walker

Charles F. Walker has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4606043
    Abstract: The circuit (10) has a gain section which includes a first AGC circuit (12). The output of the gain section goes to a signal shaping section which includes a biquadratic filter (24), a summer (45), and a second AGC circuit (40). The two AGC circuits (12,40) are controlled by respective separate peak detectors (20, 50) and are noninteracting. For "short" cables, only the first AGC circuit (12) is active. For "long" cables, the first AGC circuit (12) is set at its gain breakpoint and the second AGC circuit (40) alone has active control. The shaping section includes a biquadratic filter (24) which is a tandem arrangement of a low-pass filter (26), an inverter (28), and an integrator (32). The low pass output (35) of the integrator (32) is connected to the noninverting (+) input of the a summing amplifier (45). The input (42) of the second AGC circuit (40) is connected to the band pass output (33) of the inverter (28), while its output (44) is connected to the inverting input (-) of the summing amplifier (45).
    Type: Grant
    Filed: October 9, 1984
    Date of Patent: August 12, 1986
    Assignee: AT&T Bell Laboratories
    Inventors: Thomas J. Aprille, Jr., Yen-long Kuo, Charles F. Walker
  • Patent number: 4499455
    Abstract: Bidirectional communications between an alarm loop, comprising one or more alarm transmitters, and a remote receiver is provided through a digital transmission facility by a pair of interface units (201,301). Each interface unit, disposed at an end of the digital transmission facilities, provides encoding and decoding of signals to and from the alarm receiver. For greater reliability, each interface unit (601,701) can be adapted to select signals received from different digital transmission facilities.
    Type: Grant
    Filed: May 3, 1982
    Date of Patent: February 12, 1985
    Assignee: AT&T Bell Laboratories
    Inventors: Michael A. Leveille, Charles F. Walker