US 5,506,871 A · Adaptive equalizing system for digital communications

Abstract

An adaptive equalizing system equalizes an unequalized signal and performs carrier recovery for use in a digital communication receiver. An equalizing coefficient is initialized by a constant modulus algorithm (CMA) and the initialized equalizing coefficient is more finely updated by a stop-and-go algorithm (SGA). When the convergency by the CMA reaches a predetermined threshold value, carrier recovery is performed, while when an average value of the phase error during performing the carrier recovery is less than another predetermined threshold value, the equalizing algorithm is converted into the SGA. Thus, the adaptive equalizing apparatus can equalize the received signal more simply and reliably.

Claims10

Dependent claims

An adaptive equalizing method for digital communications in which an unequalized signal is adaptively equalized in a receiver of a digital communication system for performing carrier recovery, said adaptive equalizing method comprising the steps of:

a) initializing an equalizing coefficient based on a constant modulus algorithm (CMA);
b) receiving the initialized equalizing coefficient and equalizing the unequalized signal to perform carrier phase recovery and to update the initialized equalizing coefficient;
c) judging whether a first error value corresponding to the recovered carrier phase is smaller than a first predetermined threshold value;
and
d) equalizing and carrier-recovering the unequalized signal based on the equalizing coefficient updated by a stop-and-go algorithm (SGA) when the first error value is smaller than the first predetermined threshold value in response to the result of the step c).

2 more elements

An adaptive equalizing apparatus for digital communications in which an unequalized signal is adaptively equalized in a digital communication receiver for performing carrier recovery, comprising:

an equalizer which receives the unequalized signal and outputs an equalized signal according to an equalizing coefficient;
a first coefficient generator which receives the unequalized signal, the equalized signal and a carrier-phase recovered signal and initializes an equalizing coefficient based on a constant modulus algorithm (CMA), to update the initialized equalizing coefficient;
phase recovery means for receiving the equalized signal and outputting the carrier-phase recovered signal and a phase error signal;
and
a second coefficient generator which receives the unequalized signal, the equalized signal and the output signals of the phase recovery means, and generates the equalizing coefficient based on a stop-and-go (SGA) algorithm when a first error signal corresponding to the equalizing coefficient of the first coefficient generator is smaller than a first predetermined threshold value.

2 more elements

Dependencies are inferred from the claim text.

Adaptive equalizing system for digital communications

Life of this patent

Adaptive equalizing system for digital communications

Life of this patent

Abstract

Claims10