Patents Assigned to Mitel Canada Limited
  • Tone generator
    Patent number: 4000379
    Abstract: A modified Sallen and key active filter useful for generating tones in a tone generator which can be connected to a telephone line. The modification allows a broad range of frequencies to be generated with a relatively constant output amplitude, the output signal of which can be usefully employed for D.T.M.F. or interoffice multifrequency signal generation.
    Type: Grant
    Filed: October 23, 1974
    Date of Patent: December 28, 1976
    Assignee: Mitel Canada Limited
    Inventor: Michael C. J. Cowpland
  • Alternating current regulator for use with telephone type line
    Patent number: 3989902
    Abstract: A regulator which can be used in combination with equipment connected to a telephone type line. The regulator senses the amount of direct current being passed by the line and adjusts its internal AC impedance in inverse relationship thereto. This will shunt alternating current signals more severely when connected to short line loops having relatively small insertion loss, protecting a central office from excessive signal amplitudes.
    Type: Grant
    Filed: October 23, 1974
    Date of Patent: November 2, 1976
    Assignee: Mitel Canada Limited
    Inventor: Michael C. J. Cowpland