Patent ID: 7302183

Claim:
A WDM (wavelength division multiplexing) transmission system comprising: one or more optical repeaters; and a variable gain tilt compensator, wherein said variable gain tilt compensator is installed at an output side of any of said one or more optical repeaters along an optical transmission path, wherein each of said optical repeaters includes: means for monitoring input power and outputting values corresponding to the monitored input power, the value being expressed by decibels; and means for transferring the monitored input power value received from an upstream side optical repeater and the output value to one of a subsequent optical repeater and the variable gain tilt compensator along the optical transmission path, wherein said variable gain tilt compensator calculates a gain tilt using a linear function formula having the respective monitored input power values of said optical repeaters, through which optical signals have been passed, as input variables and determines compensation amount; and wherein the linear function formula used to calculate the pain tilt is in the form of: Δ ⁢ ⁢ G = ∑ i = 1 n ⁢ ⁢ G i = ( 2 ⁢ ( b 1 - b n ) / ( b 1 + b n ) ) ⁢ ∑ i = 1 n ⁢ ⁢ P i + C where: Δ G is the gain tilt P 1 : the monitored input power value from the i-th repeater, b 1 = g i +a i g is an emission coefficient (dB/m), α a is an absorption coefficient (dBIm), C is a Constant, and n is a number of repeaters for which the monitored input power values are input to said variable gain tilt compensator.