Automatic equalizer and method of initialization thereof

Claim 2

An automatic equalization device used in a communication system in which a transmitter and a receiver are connected by a transmission line, said transmitter including a means for transmitting an initialization signal including a component of a single pulse and subsequently transmitting a data signal, said receiver including said automatic equalization device for correcting the received signal and deriving the data signal transmitted from said transmitter, said automatic equalization device comprising: a means for extracting a single pulse having a distortion due to the characteristics of the transmission line from the received initialization signal; a means for deriving a coefficient for obtaining an auto-correlation or a cross-correlation series using said extracted single pulse; a first equalization circuit for correcting said extracted single pulse into a symmetric single pulse and correcting the data signal by the coefficient obtained by said deriving means; a generating means for generating a coefficient for deriving a single pulse coinciding with the single pulse included in the initialization signal transmitted from said transmitter, using said symmetric single pulse; and a second equalization circuit for correcting the data signal based on the coefficient obtained by said generating means.

Claim 3

An automatic equalization device which is arranged in a receiver for receiving through a transmission line and demodulating a carrier signal quadrature-amplitude modulated by digital data in a transmitter and which compensates for the distortion introduced by said transmission line into said received signal, said automatic equalization device comprising a single pulse extraction circuit for extracting the signal corresponding to the single pulse singal containing the distortion due to said transmission line from a predetermined training signal transmitted for starting-up said receiver, a first equalization circuit, and a second equalization circuit, said single pulse extraction circuit comprising a means for generating a data series corresponding to said single pulse signal, a means for normalizing said data series, and a menas for deriving the complex conjugate series of said normalized data series, said first equalization circuit comprising a means for calculating an auto-correlation series of the signal corresponding to said single pulse signal from said normalized data series using said derived complex conjugate series as a tap coefficient and a means for calculating a cross-correlation series of a data series received after the start-up and a signal corresponding to said single pulse signal also using said derived complex conjugate series as a tap coefficient, said second equalization circuit comprising a means for obtaining a data series which is the N-th order approximation of the inverse matrix of said auto-correlation series using said auto-correlation series obtained from said first equalization circuit, a means for obtaining a data series corresponding to said inverse matrix by the successive approximation method on the basis of the data series of said N-th order approximation, and a means for obtaining an equalized output from a cross-correlation series of the received data produced from said first equalization circuit by initializing the data series corresponding to said inverse matrix as a tap coefficient.

Claim 4

An automatic equalization device which is arranged in a receiver for receiving through a transmission line and demodulating a carrier signal quadrature-amplitude modulated by digital data in a transmitter and which compensates for the distortion introduced by said transmission line into said received signal, said automatic equalization device comprising a single pulse extraction circuit for extracting the signal corresponding to the single pulse singal containing the distortion due to said transmission line from a predetermined training signal transmitted for starting-up said receiver, a first equalization circuit, and a second equalization circuit, said single pulse extraction circuit comprising a means for generating a data series corresponding to said single pulse signal, a means for normalizing said data series, and a menas for deriving the complex conjugate series of said normalized data series, said first equalization circuit comprising a means for calculating an auto-correlation series of the signal corresponding to said single pulse signal from said normalized data series using said derived complex conjugate series as a tap coefficient and a means for calculating a cross-correlation series of a data series received after the start-up and a signal corresponding to said single pulse signal also using said derived complex conjugate series as a tap coefficient, said second equalization circuit comprising a means for obtaining a data series which is the N-th order approximation of the inverse matrix of said auto-correlation series using said auto-correlation series obtained from said first equalization circuit, a means for obtaining a data series corresponding to said inverse matrix by the successive approximation method on the basis of the data series of said N-th order approximation, and a means for obtaining an equalized output from a cross-correlation series of the received data produced from said first equalization circuit by initializing the data series corresponding to said inverse matrix as a tap coefficient.

Claim 5

An automatic equalization device as defined in claim 2, wherein in said means for obtaining a data series which is the N-th order approximation of the inverse matrix, when said auto-correlation series is Am (m = 0, ±1, ---, + n) said data series is obtained as a first order approximation in the form of:

Claim 6

An automatic equalization device as defined in claim 2 or 3, wherein, in said means for obtaining a data series corresponding to said inverse matrix, the Gauss-Seidel method is as used the successive approximation method and the data series corresponding to said inverse matrix is obtained by coreecting said data series: in the sequence B 0 , B ±1 , ---, B ±n and subsequently repeating the correction.

Claim 9

A method of starting-up an automatic equalization device as defined in claim 5, whrein said training signal contains the carrier signal modulated by a specific data series, said specific data series being such thai. by obtaining the sum or difference between said specific data series and the data series which is shifted from said specific data series by one data symbol, a single pulse series, i.e., a series in which only the central component is (1, 0) and the other components are (0, 0), is obtained.