Patent ID: 7623790

Claim:
A method for identifying characteristics of an optical signal, comprising: receiving a data sample representing a first optical signal; said receiving step comprising the steps of: providing an optical fiber having an amount of optical power therein; tapping off a fraction of the optical power present in the optical fiber; obtaining an optical power spectrum; and parsing the optical power spectrum into a plurality of data samples associated with particular channels of a wavelength division multiplexing communication system; wherein each of the data samples comprises a plurality of data points; and wherein obtaining the optical power spectrum is limited to a first resolution by the characteristics of an optical spectrum analyzer, and wherein at least one signal characteristic attributed to the first optical signal has a resolution finer than the first resolution; comparing the data sample to a set of pre-stored model curves, each model curve representing at least one signal characteristic using a curve-fit analysis; determining, for each comparison, an error value representing a quantity of difference between the data sample and a particular one of the pre-stored model curves; selecting one of the pre-stored model curves with an error value having a least quantity of difference; attributing to the first optical signal the at least one signal characteristic of the selected one of the pre-stored model curves; and determining center frequency detuning from an ITU grid for the optical signal by performing a least-squares estimate for each characteristic functional form several times with small discrete frequency shifts to the functional form applied each time.