Patent ID: 6236687
Filing Date: 2001-05-22
Classification: H04L

Abstract:
A decision directed phase locked loop (DD-PLL) for use in a data communication system, comprising:a first converter which converts a baseband quadrature pair of an input modulated signal encoded by a sequence of codewords from a rectangular form into a pair of polar coordinates having an incoming phase;a comparator which generates a phase difference of said incoming phase of said input modulated signal and an estimated phase;a second converter which converts said polar coordinates having said phase difference into a set of vector pairs of phase stabilized observables in said rectangular form;a decoder which decodes said set of vector pairs of phase stabilized observables in said rectangular form at a decode rate to generate decoded data;a vector error evaluator which evaluates said set of vector pairs of phase stabilized observables in accordance with said decoded data at each codeword to generate a decision directed phase error estimate; anda loop filter which filters said decision directed phase error estimate to yield an update of said estimated phase at each codeword.