Patent ID: 8447190

Claim:
A distortion compensating apparatus for compensating for distortion in a waveform of a received light signal through digital signal processing, the distortion compensating apparatus comprising: a plurality of fixed amount compensators which compensate for the distortion in the waveform at respective given compensating amounts, wherein a combination of operating states of the plurality of fixed amount compensators is changed by on/off switching of each of the plurality of fixed amount compensators; and a controller which controls the on/off switching and thereby changes the combination, based on the distortion in the waveform caused by an optical transmission path through which the received light signal propagates, wherein the plurality of fixed amount compensators are cascaded, wherein each of the plurality of fixed amount compensators has coefficient patterns including an off coefficient pattern that makes the each of the plurality of fixed amount compensators switched off, and wherein the controller switches the operating state of each of the plurality of fixed amount compensators by selecting a coefficient pattern except the off coefficient pattern when each of the plurality of fixed amount compensators is switched on, and selecting the off coefficient pattern when each of the plurality of fixed amount compensators is switched off.