公开(公告)号：DE2221276A1

公开(公告)日：1972-12-07

申请号：DE2221276

申请日：1972-04-29

Applicant: IBM

Inventor： SHA RICHARD TZING-YEN ,  TANG DONALD TAO-NAN

IPC: H04L25/03 ,  H04L25/04

Abstract: A recursive automatic equalizer with extremely fast convergence is disclosed. The equalizer includes a plurality of equalizer stages connected in cascade which first reduces impulse response of the communication channel to substantially zero. The front portion or sidelobe is reduced to substantially zero distortion by adjusting the tap settings of successive equalizer stages after successive iterations (the first iteration adjusts the tap settings of the first equalizer stage, the second iteration adjusts the tap settings of the second equalizer stage, and so on) such that after n iterations a given initial distortion D is reduced to substantially zero. The tap setting algorithm involved and the method of operating the cascaded equalizer is disclosed. Finally, after n iterations, the output signal which can be described by the function 1-A(n) is modified by the reciprocal of the foregoing function and, is this manner, the rear or trailing portion of an input signal which is to be equalized has its rear sidelobe distortion reduced to substantially zero leaving only the desired main pulse. Apparatus for modifying the trailing or rear end of a pulse to be equalized is also disclosed.