Patent ID: 6917031
Filing Date: 2005-07-12
Classification: H04B

Abstract:
1. A method for correcting in an optical coherent receiver a quadrature angle error (θ), wherein a first detected signal is a detected in-phase signal represented in a form I(t) and a second detected signal is desired to be in quadrature with respect to the first detected signal but is offset from being in quadrature by the quadrature angle error, the second detected signal represented in a form I(t)sin(θ)+Q(t)cos(θ), the method comprising generating an estimate of the quadrature angle error by multiplying the first detected signal and the second detected signal together to generate a product that is proportional to the quadrature angle error; and compensating for the quadrature angle error by multiplying the first detected signal and the second detected signal by coefficients which are a function of the estimate of the quadrature angle error that substantially cancel the quadrature angle error.