Equalizer comprising first and second equalizing means and trainable in two steps

DETAILED DESCRIPTION What is claimed is: 1.
An equalizer, supplied with signals produced in a transmitter at a predetermined clock interval, for producing an equalized signal, said supplied signals including a first and a second pseudo-noise train successively produced in said transmitter, said first pseudo-noise train consisting of a series of partial trains, each of said partial trains having a first period and a predetermined pattern of pulses, said second pseudo-noise train having a second period longer than said first period, which comprises: a delay line having a plurality of taps for delaying said supplied signals by a total equal at least to said first period to produce delayed signals from the respective taps; a series of adjustable gain circuits connected to the respective taps and retaining adjustable gains for giving the adjustable gains to said delayed signals, respectively, to produce amplitude-varied signals; a noise generator for producing a generated pseudo-noise train consisting of said predetermined patterns of pulses; first equalizing means, supplied with said generated pseudo-noise train and the amplitude-varied signals produced in response to said first pseudo-noise train by those central ones of said adjustable gain circuits which are connected to consecutive ones of said taps at which said first pseudo-noise train is delayed by a delay equal in total to said first period, for adjusting the adjustable gains retained by said central adjustable gain circuits to make a thereby produced first output signal of said first equalizing means simulate said generated pseudo-noise train; cyclic permutation means for subjecting said adjusted gains to cyclic permutation in said central adjustable gain circuits to make those of said central adjustable gain circuits which are placed at a center portion of the series of said central adjustable gain circuits retain larger ones, in absolute values, of said adjusted gains; and second equalizing means supplied with the amplitude-varied signals produced in response to said second pseudo-noise train by all of said adjustable gain cicuits for self-adaptively adjusting the adjustable gains retained by said all adjustable gain circuits to make a thereby produced second output signal of said second equalizing means become said equalized signal