Optical transmission system, transmission apparatus, receiving apparatus and method for device characteristic estimation

An optical transmission system comprising:

• a transmission apparatus;
• and
• a receiving apparatus, wherein:
• the transmission apparatus includes
• a pre-equalizer that performs pre-equalization on digital transmission signals by using a compensation filter,
• a digital-to-analog converter that converts the digital transmission signals which have been pre-equalized from digital signals into analog signals, so as to output analog transmission signals, and
• an electrical-to-optical converter that converts the analog transmission signals from electrical signals into optical signals so as to output optical transmission signals;
• the receiving apparatus includes
• a receiver that receives the optical transmission signals which have been output from the output unit electrical-to-optical converter, converts the optical transmission signals from the optical signals into the electrical signals so as to output analog received signals,
• an analog-to-digital converter that converts the analog received signals from the analog signals into the digital signals so as to output digital received signals, and
• a demodulator that demodulates the digital received signals;
• and
• the optical transmission system further includes
• a scale estimation processor that calculates a slope near an amplitude 0 in a correlation between an amplitude distribution of the digital transmission signals which have been pre-equalized by the pre-equalizer and an amplitude distribution of the digital received signals,
• a scale processor that scales an amplitude of the digital received signals on the basis of the slope which has been calculated by the scale estimation processor,
• a coefficient estimation processor that calculates a filter coefficient of the compensation filter on the basis of the digital transmission signals which have been pre-equalized by the pre-equalizer and the digital received signals which have been scaled by the scale processor, and
• an output amplitude level determination processor that determines an output level of the analog transmission signals output from the digital-to-analog converter on the basis of a correlation between a distribution of amplitudes of the digital transmission signals before being pre-equalized by the pre-equalizer and a distribution of amplitudes of the digital transmission signals which have been pre-equalized by the pre-equalizer.