GB1502454A - Method of providing automatic adaptive equalization of multiphase modulated data signals - Google Patents

Abstract

1502454 Equalizers for N-phase signalling systems INTERNATIONAL STANDARD ELECTRIC CORP 23 May 1975 [1 July 1974] 22907/75 Heading H4R In an automatic adaptive equalizer for an N- phase modulated transmission system in which the in-phase components x k and the quadrature components y k are fed to respective delay systems 1 to N and the signals at each of the tappings are multiplied by coefficients C(1) to C(N) to provide "in-channel" equalization, and multiplied by coefficients d(1) to d(N) to provide "cross-channel" equalization with the output of each "in channel" equalizer being combined with the cross-channel equalizer of the other channel to provide the respective in-phase output ik and quadrature output q k , the multipliers of the equalizers are up dated by correlation between the signals at the delay system taps and a common error signal, the same error signal being used for adjustment of all the multipliers. As described the error signal is derived from the error in magnitude of the "inphase" component relative the nearest reference value, with the reference value being fixed arithmetically in the case of four phase signalling, and derived as one of two possible values in the case of 8 phase signalling the particular valve being chosen in dependence on the polarity of a comparison of the absolute magnitudes of the inphase and quadrature components of the signal. Detector circuits for the error signals for the eight phase and four phase systems are described with respect to Figs. 2a and 3a (not shown).