Chromatic dispersion value calculating apparatus, optical signal receiving apparatus, optical signal transmitting apparatus, and chromatic dispersion value calculation method

A chromatic dispersion value calculation method comprising:

• a signal distributing step of distributing, into a plurality of signal sequences, an electrical digital signal in each of polarized waves converted from a received optical signal in each of the polarized waves of an optical signal transmitted by an optical signal transmitting apparatus in which a training signal sequence in which second specific frequency band signal sequences with power concentrated in a specific frequency band which differs from a first specific frequency band signal sequence with power concentrated in a plurality of specific frequency bands are appended before and after the first specific frequency band signal sequence, is time-division multiplexed with a transmission data sequence;
• a filtering step of separating each of a plurality of specific frequency components with power concentrated in the first specific frequency band signal sequence, from each of the plurality of signal sequences distributed in the signal distributing step;
• a power calculating step of calculating power values of the signal sequences of the plurality of specific frequency components separated in the filtering step;
• a multiplexing step of synthesizing signal sequences of the power values corresponding to different polarized waves of the same specific frequency component, among the power values calculated in the power calculating step;
• an averaging step of averaging consecutive signal sequences synthesized in the multiplexing step;
• and
• a delay time calculating step of detecting times at which power has the maximum value or times at which the power exceeds a predetermined threshold value from a signal sequence averaged in the averaging step, comparing the detected times, and outputting a delay time obtained as a result of comparison or a chromatic dispersion value calculated from the delay time.

An optical signal transmitting apparatus comprising:

• a specific frequency band signal generating circuit which generates a known signal with frequency components concentrated in a plurality of specific frequency bands including first specific frequency bands and a second specific frequency band which differs from the first specific frequency bands, the known signal including a first specific frequency band signal with power concentrated in the first specific frequency bands and second specific frequency band signals which are appended before and after the first specific frequency band signal, the second specific frequency band signals having power concentrated in the second specific frequency band;
• a signal multiplexing circuit which appends the known signal generated by the specific frequency band signal generating circuit to a signal generated from a transmission data sequence;
• and
• an electro-optical conversion circuit which converts an electrical signal generated by the signal multiplexing circuit into an optical signal.

An optical signal transmitting apparatus comprising:

• a specific frequency band signal generating circuit which generates a known signal with frequency components concentrated in a plurality of specific frequency bands;
• a signal multiplexing circuit which appends the known signal generated by the specific frequency band signal generating circuit to a signal generated from a transmission data sequence;
• and
• an electro-optical conversion circuit which converts an electrical signal generated by the signal multiplexing circuit into an optical signal,
• wherein
• the specific frequency band signal generating circuit generates the known signal by generating a first specific frequency band signal sequence with power concentrated in a plurality of specific frequency bands and second specific frequency band signal sequences with power concentrated in a specific frequency band different from the first specific frequency band signal sequence, and generating a training signal sequence in which the second specific frequency band signal sequences are time-division multiplexed immediately before and immediately after the first specific frequency band signal sequence, and
• the signal multiplexing circuit generates a signal sequence in which the training signal sequence generated by the specific frequency band signal generating circuit is inserted into the transmission data sequence by means of time-division multiplexing.