Fast start-up system for transversal equalizers

Abstract

A fast start-up system is disclosed for a transversal equalizer comprising a transmitter capable of generating a periodic symbol sequence with a period L, the auto correlation function of said sequence being 0, except for its center. The system generates and transmits a test signal based upon the generated symbol sequence. A receiver generates the same periodic symbol sequence as that generated in the transmitter in a proper phase relation thereto according to a received signal. The correlation between L sampled values and a sequence obtained by recirculating the periodic symbol sequence for each of consecutive M shifted phases, and for each of M' consecutive shifted phases is calculated. The calculated M+M' correlation values are multiplied by a constant. A discrete Fourier transform is obtained for the M+M' multiplied correlation values at N points equal to or greater than M+M' in number. The values of a predetermined frequency characteristic for frequency points obtained from the discrete Fourier transform are stored. The stored values are then divided by the respective values obtained by the discrete Fourier transform and the inverse discrete Fourier transform of the N divided values is obtained. The numerical values obtained as the inverse discrete Fourier transform are used to initialize the tap gain of a transversal automatic equalizer with a basic delay interval equal to one half the symbol interval, thereby permitting a sufficiently equalized state to be realized rapidly with a short test sequence.