Equalizer comprising first and second equalizing means and trainable in two steps
AssigneeNippon Electric Co., Ltd.
InventorYoichi Sato
Life of this patent
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Abstract
An equalizer comprises a tapped delay line of a transversal filter and first equalizing means responsive to a short pseudo-noise train supplied thereto for adjusting tap gains so as to make the transversal filter output signals simulate a pseudo-noise train generated at the receiver with the pulse pattern of the supplied pseudo-noise train. Larger ones, in absolute values, of the adjusted gains are placed at the center of the delay line. Responsive to a subsequently supplied long pseudo-noise train, second equalizing means self-adaptively adjusts all tap gains. The delay line preferably comprises delay units, each for a half of a common clock interval of the supplied pseudo-noise trains and data signals.
Claims15
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.
Dependencies are inferred from the claim text.