Patent ID: 6836620
Filing Date: 2004-12-28
Classification: H04B

Abstract:
A method for monitoring signal quality of a signal in a transparent optical transmission path, the method comprising:sampling the signal asynchronously to obtain amplitude samples, wherein the signal is sampled at a substantially lower rate than a bit repetition rate of the signal; determining positions of local maxima (a, b) in a probability density function (ps(s)) of the amplitude samples for a low logic state 0 denoted by â€œaâ€  and for a high logic statement 1 denoted by â€œbâ€ ; determining a standard deviation (sa, sb) for at least one maximum (a, b) only from values of the probability density function belonging to a flank of the respective maximum facing away from the respective other maximum; and determining a signal quality parameter Q from the determined values.