Method of measuring quality of a signal received by a receiver of a

Abstract

A quality measure of a signal received at a receiver of a two-dimensional linear modulation data communication system, is measured by using a phase controlled baseband signal (y.sub.k.exp(j.phi..sub.k)) obtained from the received signal and a reproduced data signal (x.sub.k) derived from the phase controlled baseband signal. That portion of the quality measure which is introduced into the received signal in a transmission channel for the received signal, is measured by estimating a data signal component (y.sub.k) which includes intercode interference, by subtracting the data signal component from the phase controlled baseband signal to produce a difference signal of a phase difference relative to the reproduced data signal, by giving the phase difference to the difference signal to produce a phase adjusted signal, and by calculating a mean square of an inphase component of the phase adjusted signal. Portions of the quality measure which are related to a carrier phase jitter component and a carrier frequency offset component, are measured also by the use of the phase controlled baseband signal and the reproduced data signal. It is possible to carry out the method by a signal processor.