Patent ID: 8390798

Claim:
A wavelength dispersion measurement method with respect to an optical transmission system in which signal light transmitted from a first terminal station and propagated through a first transmission path is received by a second terminal station, and signal light transmitted from the second terminal station and propagated through a second transmission path different from the first transmission path is received by the first terminal station, the wavelength dispersion measurement method comprising: generating a plurality of test lights in the first terminal, the wavelengths of which are different from a wavelength of the signal light propagated between the first and the second terminal stations; multiplexing each test light with the signal light and outputting the multiplexed light from the first terminal station to the first transmission path; reconverting each electrical signal into each test light after receiving in the second terminal station each test light propagated through the first transmission path and converting each test light into electrical signals; multiplexing each test light with the signal light and outputting the multiplexed light from the second terminal station to the second transmission path; reconverting each electrical signal into the each test light after receiving in the first terminal station each test light propagated through the second transmission path and converting each test light into electrical signals; multiplexing each test light with the signal light and outputting the multiplexed light from the first terminal station to the first transmission path; measuring times for each test light to be propagated up to a specified number of go-around, with respect to each wavelength; and measuring a change of a wavelength dispersion amount in the first and the second transmission paths based on a difference between the measured propagation times of each wavelengths.