Patent ID: 9124363
Filing Date: 2015-09-01
Classification: H04B

Abstract:
1. A method comprising: receiving on an optical fiber an optical field comprised of a plurality of subchannels of optical signals at respective wavelengths; using coherent optical reception in conjunction with analog-to-digital conversion, converting the received optical field to digital complex valued data; transforming the digital complex valued data to the frequency domain to produce electrical spectrum data; and computing a distance between a subchannel of interest among the plurality of subchannels and at least one neighbor subchannel based on the electrical spectrum data, wherein the computing comprises measuring a distance between points in the electrical spectrum data that are on opposite sides of a minimum point and which are at a predetermined power level, and adding a correction term to the measured distance to determine a distance between a center of the subchannel of interest and a center of the neighbor subchannel.