Patent ID: 6272186
Filing Date: 2001-08-07
Classification: H04L

Abstract:
A method of determining the presence of a verification sequence in a received sample stream arriving at respective sample times and having a received sample rate, said verification sequence consisting of a plurality of samples including a first sample, said received sample stream being obtained from a transmitted symbol stream having a transmitted symbol rate and having undergone dispersion, said dispersion being characterized by a plurality of dispersion coefficients, the method comprising the steps of:determining a reference sample time;for each one of a plurality of sample shifts indicating possible locations for the first sample of the verification sequence relative to the reference sample time: calculating at least two estimates for each of the plurality of dispersion coefficients; calculating the variation among the at least two estimates for each of the plurality of dispersion coefficients; and combining the calculated variations into a combined metric associated with the sample shift; andif the combined metric associated with at least one of the sample shifts is below a predetermined threshold, deciding that the verification sequence is present in the received sample stream.