A signal identification method for efficiently identifying Dense Wavelength Division Multiplexing (DWDM) channel modulation formats, signal powers, and center frequency detuning of signals that may be used in conjunction with telecom-grade monitoring equipment. The method utilizes least-square curve fitting estimates applied to a set of curves, each curve is characteristic of a modulation format and rate. For each least-square estimate an error value is calculated, and a curve fit with the least error is selected as the identified signal format for a signal.