Patent ID: 8655195

Claim:
An apparatus for detecting average length magnitude comprising: a processor, configured to determine a magnitude of a residual polarization crosstalk coefficient of the receiver, and determines an index that indicates whether the average length of the averager is long or short according to the determined magnitude of the residual polarization crosstalk coefficient; wherein, the apparatus is configured to detect whether an average length of an averager used by a polarization crosstalk canceling apparatus in a receiver is long or short and the processor uses one of the following two solutions to determine the index: solution 1 the processor delays the residual polarization crosstalk coefficient by one or more symbols, conjugates the delayed signals, multiplies the coefficient for residual polarization crosstalk and the conjugated signals, averages results of the multiplying, and calculates real parts of the averaged signals, solution 2 the processor calculates real part of the coefficient for residual polarization crosstalk, calculates imaginary part of the coefficient for residual polarization crosstalk, delays the real part by one or more symbols, delays the imaginary part by one or more symbols, multiplies the delayed real part and the un-delayed real part to acquire results of multiplying the real parts, multiplies the delayed imaginary part and the un-delayed imaginary part to acquire results of multiplying the imaginary parts, adds the results of multiplying the imaginary parts and the results of multiplying the real parts, and averages results of the adding.