Patent ID: 7277502
Filing Date: 2007-10-02
Classification: H04L

Abstract:
1. A carrier recovery apparatus comprising: a numerical control oscillating means for outputting a complex oscillation signal; a complex multiplying means for multiplying a modulated signal being input and an output of said numerical control oscillating means; a phase error detecting means for detecting a phase error between the modulated signal and the complex oscillation signal on the basis of the output of said complex multiplying means; and a loop filter for controlling said numerical control oscillating means by filtering the phase error, wherein a carrier of the modulated signal is recovered by said numerical control oscillating means; and wherein said phase error detecting means comprises: a symbol estimating means for estimating a symbol on the basis of an output of said complex multiplying means; a second complex multiplying means for multiplying an output of said symbol estimating means and an output of said complex multiplying means; an imaginary number selecting means for selecting a Q signal axis component of an output of said second complex multiplying means; a complex subtracting means for calculating an amplitude error by complex subtraction of the output of said complex multiplying means and the output of said symbol estimating means; a phase error judging means for judging if the output of said second complex multiplying means is an error in phase direction or not on the basis of the amplitude error; and a selecting means for outputting only the error in the phase direction out of an output of said imaginary number selector on the basis of an output of said phase error detecting means.