Jitter equalizer for digital transmission filter

Claim 1

An equalizer for equalizing jitter, overshoot and undershoot in the amplitude of a transmission signal input for a digital transmission filter, comprising: delay means having a plurality of delay elements, for synchronizing a random non-return-to-zero (NRZ) input data signal input thereto with a basic clock signal input thereto to produce a delayed input data signal which is delayed by a predetermined number of data bits, and for outputting a plurality of data bits of a data stream, each of said data bits respectively corresponding to one of said plurality of delay elements; logic circuit means coupled with outputs of said delay means and receiving said output data stream therefrom, for producing a plurality of control voltage signals corresponding to patterns of logic symbols of said input data signal from said plurality of bits of said data stream, said plurality of voltage control signals designating information as to how much said delayed input data signal will be distorted by data signals adjacent thereto upon passing through a digital transmission filter; adding and subtracting voltage generator means coupled to an output of said logic circuit means, for outputting a given level of an adding or subtracting voltage in response to said plurality of voltage control signals from said logic circuit means under the control of a time control signal applied thereto; unipolar-to-bipolar converter means coupled to said delay means, for converting said delayed input data signal from a unipolar input data signal to a bipolar input data signal; and adder means coupled to respective outputs of said unipolar-to-bipolar converter means and said adding and subtracting voltage generator means, for adding said bipolar input data signal to said given level of adding or subtracting voltage, the added output of said adder means compensating for an amount of signal distortion which will arise in an output waveform of a digital transmission filter due to the influence of pulse tails of data signals adjacent to said input data signal when said bipolar input data signal passes through said filter.

Claim 14

A method for equalizing jitter, overshoot and undershoot phenomena in a digital transmission filter, comprising the steps of: making a pre-estimate as to the extend of signal distortion which will be caused by the sum of pulse tails in pulse waveforms data patterns adjacent data an input data signal during passage of said input data signal through a digital transmission filter, according to logic states of said adjacent data patterns; on the basis of said pre-estimate, equalizing said input data signal, prior to passing through said filter, with a higher amplitude of an output square wave than a mean level of said sum of said pulse tails, when said sum of said pulse tails increases in a negative direction; and on the basis of said pre-estimate, equalizing said input data signal, prior to passing through said filter, with a lower amplitude of an output square wave than the mean level of said sum of said pulse tails, when said sum of said pulse tails increases in a positive direction.

Claim 15

A method for equalizing jitter, overshoot and undershoot phenomena in a digital transmission filter, comprising the steps of: making a pre-estimate as to the extend of signal distortion which will be caused by the sum of pulse tails in pulse waveforms data patterns adjacent data an input data signal during passage of said input data signal through a digital transmission filter, according to logic states of said adjacent data patterns; on the basis of said pre-estimate, equalizing said input data signal, prior to passing through said filter, with a higher amplitude of an output square wave than a mean level of said sum of said pulse tails, when said sum of said pulse tails increases in a negative direction; and on the basis of said pre-estimate, equalizing said input data signal, prior to passing through said filter, with a lower amplitude of an output square wave than the mean level of said sum of said pulse tails, when said sum of said pulse tails increases in a positive direction.