Patent ID: 6339623
Filing Date: 2002-01-15
Classification: H03D,H03J,H03L,H04L

Abstract:
A reference carrier generator device comprising:a phase error detection unit for detecting a phase error based on quadrature demodulated signals, and for outputting a phase error signal indicating the phase error; a loop filter for passing the phase error signal from the phase error detection unit through the loop filter, and for converting the phase error signal into a control voltage; a voltage-controlled oscillator for outputting a reference carrier synchronous with a quadrature modulated wave based on the control voltage; and a sweep unit for changing the control voltage to the oscillator when pulling the reference carrier into synchronism in response to an incoming out-of-sync alarm signal, wherein the sweep unit outputs a staircase sweep signal having a rising edge with a selected level which discontinuously varies at random from one of a plurality of discrete values to another of said plurality of discrete values, the staircase sweep signal being added to the phase error signal such that the control voltage output to the oscillator is intermittently changed to another voltage and said another voltage is intermittently retained by the staircase sweep signal.