Patent ID: 6307898
Filing Date: 2001-10-23
Classification: H04L

Abstract:
A phase error detector for use in a demodulator recovering a carrier signal from a received signal, using the recovered carrier signal to demodulate the received signal, thereby obtaining an in-phase demodulated signal representing transmitted data values, also obtaining a quadrature demodulated signal, comprising:a data decision circuit determining the transmitted data values represented by said in-phase demodulated signal;a subtractor coupled to said data decision circuit, taking a difference between said in-phase demodulated signal and said transmitted data values, thereby generating a difference signal;a sign estimator coupled to said subtractor, using said quadrature demodulated signal and said difference signal to estimate whether said recovered carrier signal leads or lags a correct phase, thereby generating a sign signal;a gain setting circuit multiplying said in-phase demodulated signal by a constant gain, thereby generating a product signal;a sign setting circuit coupled to said gain setting circuit and said sign estimator, reversing a polarity of said product signal according to said sign signal, thereby generating a signed product signal;an adder coupled to said sign setting circuit, adding said signed product signal to said quadrature demodulated signal, thereby generating a sum; anda divider coupled to said adder, dividing said difference signal by said sum, thereby generating an estimated phase error.