Patent ID: 6697577
Filing Date: 2004-02-24
Classification: H04B

Abstract:
A tuning system for use in a receiver of an optical transmission system, the receiver including a data channel transporting a data signal and a monitoring channel transporting a copy of the data signal, the receiver applying a first decision threshold on the data signal transported on the data channel and a second decision threshold on the copy of the data signal transported on the monitoring channel in order to discriminate one binary value from another on the respective channel, each of the data and monitoring channels being characterized by a respective bit error rate, said tuning system including:a first input for receiving the data signal transported on the data channel; a second input for receiving the copy of the data signal transported on the monitoring channel; a processing module coupled to said first and second inputs for processing the copy of the data signal, said processing module operative to: a) vary the second decision threshold of the receiver across a range of predetermined values in order to alter the bit error rate of the monitoring channel; b) for different values of the second decision threshold of the receiver, measure the corresponding bit error rate of the monitoring channel; c) for certain predetermined bit error rate values of the monitoring channel, identify the corresponding second decision threshold values; d) compute for each predetermined bit error rate value and corresponding second decision threshold value of the monitoring channel an associated Q factor; e) utilize the second decision threshold values corresponding to the certain predetermined bit error rate values and the associated Q factors of the monitoring channel to compute an optimum value for the first decision threshold of the receiver; f) set the first decision threshold of the receiver to the computed optimum value.