Patents Assigned to Telecummunications Radioelectriques et Telephoniques T.R.T.
  • Patent number: 4587498
    Abstract: A circuit for recovering the carrier of an amplitude-and-phase-modulated input signal (in particular QAM signal) is provided with a frequency-controlled oscillator for producing the carrier, with a quadrature detector for supplying signals representing the amplitude of the input signal projected on two quadrature components P and Q of the carrier signal produced by the oscillator and for thus determining the modulation states of the input signal, and with correction means for forming a correction signal for the frequency control of the oscillator on the basis of output signals from a circuit which determines zones in the plane of the quadrature components P and Q. To provide for a satisfactory operation also in the presence of selective fading, the correction means comprises a weighting circuit connected to the zone-determining circuit for producing the correction signal in accordance with distinct weights allocated to the respective zones defined by the zone-determining circuit.
    Type: Grant
    Filed: March 7, 1984
    Date of Patent: May 6, 1986
    Assignee: Telecummunications Radioelectriques et Telephoniques T.R.T.
    Inventors: Georges Bonnerot, Michel Daout