원래 이름 기록: Nippon Telegraph and Telephone Corporation

A calculation apparatus () calculates an input power to an optical fiber transmission path of each channel in two adjacent bands. The calculation apparatus () assumes that a transition of a span incoming power due to an influence of stimulated Raman scattering depends on the number of existing channels in an optical fiber transmission path, and calculates an input power for eliminating a slope of the span incoming power using a coefficient r indicating a power ratio of a target channel and an adjacent channel.