Patent ID: 7603044

Claim:
A method for calibrating orthogonal polarity in a multichannel optical transport network (OTN) receiver, the method comprising: accepting a pair of 2 n -phase shift keying (2 n -PSK) modulated input signals via Ix and Qx optical signal paths, where n≧1; accepting a pair of 2 p -PSK modulated input signals via Iy and Qy optical signal paths where p≧1; generating polarization-adjusted I′x, Q′x, I′y, and Q′y signals by initially finding: Iy=Iy *cos P−Qy *sin P; Qy=Qy *cos P+Iy *sin P ; and, subsequently calculating: I′x=Ix *cos N+Iy *sin N; Q′x=Qx *cos N+Qy *sin N; I′y=− ( Ix *sin N )+ Iy *cos N; Q′y=− ( Qx *sin N )+ Qy *cos N ; comparing an average magnitude to a magnitude selected from a group consisting of 2×the absolute magnitude of (I′x and Q′x) and 2×the absolute magnitude of (I′y and Q′y); and, modifying the polarization-adjusted I′x, Q′x, I′y, and Q′y signals until the magnitude comparison is about zero by: fixing as a constant an angle selected from a group consisting of P and N; iteratively varying the unselected angle until a minimum magnitude comparison is obtained; fixing the unselected angle as a constant; and, varying the selected angle until the magnitude comparison is about zero.