Patent ID: 8755696

Claim:
A control apparatus for controlling an optical receiver having delay paths, the control apparatus comprising: an optical variable attenuator configured to generate a variable signal and provide the variable signal to the optical receiver; a fine control voltage controller configured to generate a variable fine control voltage and input the variable fine control voltage to one path of the delay paths of the optical receiver; a photo-diode voltage monitor configured to detect a first voltage value and a second voltage value which are, respectively, applied to two photo-diodes in the optical receiver; a bit error rate (BER) checker configured to estimate a bit error rate (BER) according to a signal output from the optical receiver; and a controller configured to set a value of the variable signal generated by the optical variable attenuator and a value of the variable fine control voltage generated by the fine control voltage controller and to estimate the fine control voltage that makes the bit error rate a minimum according to the first voltage value and the second voltage value, wherein the controller is configured to identify in a graph made using the acquired information a section in which a first voltage value is greater than a second voltage value and a section in which the second voltage value is greater than the first voltage value, and to adjust a fine control voltage value to be optimized for each section.