TRANSFER FUNCTION ESTIMATION DEVICE, TRANSFER FUNCTION ESTIMATION METHOD AND PROGRAM
A transfer function estimation device includes a composite transfer function calculation unit that calculates a composite transfer function which is obtained by combining a transmission transfer function that affects a signal transmitted by an optical transmitter and a reception transfer function that affects a signal received by an optical receiver in each of frequency offsets that are differences between a frequency of a carrier wave input to an optical modulation unit in the optical transmitter and a frequency of a carrier wave input to an optical demodulation unit in the optical receiver based on a signal transmitted by the optical transmitter and a signal received by the optical receiver, and a transfer function separation unit that calculates the transmission transfer function and the reception transfer function from the composite transfer function based on dependency of the composite transfer function on the frequency offset.
1 . A transfer function estimation device comprising:
a composite transfer function calculator that calculates a composite transfer function which is obtained by combining a transmission transfer function that affects a signal transmitted by an optical transmitter and a reception transfer function that affects a signal received by an optical receiver in each of frequency offsets that are differences between a frequency of a carrier wave input to an optical modulation unit in the optical transmitter and a frequency of a carrier wave input to an optical demodulation unit in the optical receiver based on a signal transmitted by the optical transmitter and a signal received by the optical receiver; and
a transfer function separator that calculates the transmission transfer function and the reception transfer function from the composite transfer function based on dependency of the composite transfer function on the frequency offset.
2 . The transfer function estimation device according to claim 1 , wherein the transfer function separator includes
an amplitude characteristic calculator that calculates an amplitude characteristic of the composite transfer function,
a phase characteristic calculator that calculates a phase characteristic of the composite transfer function,
an amplitude characteristic separator that calculates an amplitude characteristic of the transmission transfer function and an amplitude characteristic of the reception transfer function based on dependency of an amplitude characteristic of the composite transfer function on the frequency offset,
a phase characteristic separator that calculates a phase characteristic of the transmission transfer function and a phase characteristic of the reception transfer function based on dependency of a phase characteristic of the composite transfer function on the frequency offset,
an optical transmitter transfer function calculator that calculates the transmission transfer function based on the amplitude characteristic and the phase characteristic of the transmission transfer function, and
an optical receiver transfer function calculator that calculates the reception transfer function based on the amplitude characteristic and the phase characteristic of the reception transfer function.
3 . The transfer function estimation device according to claim 2 , wherein the amplitude characteristic separator calculates the amplitude characteristic of the transmission transfer function and the amplitude characteristic of the reception transfer function by performing polynomial fitting of the amplitude characteristic of the composite transfer function to the frequency offset, and the phase characteristic separator calculates the phase characteristic of the transmission transfer function and the phase characteristic of the reception transfer function by performing polynomial fitting of the phase characteristic of the composite transfer function to the frequency offset.
4 . A transfer function estimation method comprising:
calculating a composite transfer function which is obtained by combining a transmission transfer function that affects a signal transmitted by an optical transmitter and a reception transfer function that affects a signal received by an optical receiver in each of frequency offsets that are differences between a frequency of a carrier wave input to an optical modulation unit in the optical transmitter and a frequency of a carrier wave input to an optical demodulation unit in the optical receiver based on a signal transmitted by the optical transmitter and a signal received by the optical receiver; and
calculating the transmission transfer function and the reception transfer function from the composite transfer function based on dependency of the composite transfer function on the frequency offset.
5 . A non-transitory storage medium storing a program for causing a computer to operate as the transfer function estimation device according to claim 1 .