Adaptive equaliser with asynchronous detection and inhibit signal generator

A receiver having an optical front end for receiving an optical signal and outputting a received signal in electrical form, the receiver also having an adaptive equaliser for equalising the received signal, the adaptive equaliser having:

• an equaliser coupled to equalise the received signals according to equalisation coefficients, to provide equalised signals having a representation of amplitudes and phases of the received signals;
• a detector for resolving data from the equalised signals;
• an asynchronous detection part for generating phase tracking information based on the resolved data and the equalised signals;
• an error estimator for estimating a phase corrected error based on the equalised signals, the phase tracking information, and the data;
• an inhibit signal generator for generating an inhibit signal to inhibit updating of the equalisation coefficients, the inhibit signal representing a likelihood of the phase corrected error being accurate, determined according to the phase corrected error, and according to the equalised signals;
• and
• a coefficient generator for adapting the equalisation coefficients for the equaliser based on the received signals, based on the phase corrected error, and arranged to inhibit the adapting according to the inhibit signal.

A method of generating updated coefficients for an adaptive equaliser, the adaptive equaliser having an equaliser for outputting equalised signals and a detector for resolving data from the equalised signals, the method having the steps of:

• generating phase tracking information using asynchronous detection based on the resolved data, and the equalised signals;
• estimating a phase corrected error based on the equalised signals, the phase tracking information, and the resolved data;
• generating an inhibit signal to inhibit updating of the equalisation coefficients, the inhibit signal representing a likelihood of the phase corrected error being accurate, determined according to the phase corrected error, and according to the equalised signals;
• adapting the equalisation coefficients for the equaliser based on the received signals, and based on the phase corrected error;
• and
• inhibiting the adapting according to the inhibit signal.

A non-transitory computer-readable storage medium having instructions stored therein, which when executed by a processor, cause the processor to carry out the method of generating updated coefficients for an adaptive equaliser, the adaptive equaliser having an equaliser for outputting equalised signals and a detector for resolving data from the equalised signals, the method having the steps of:

• generating phase tracking information using asynchronous detection based on the resolved data, and the equalised signals;
• estimating a phase corrected error based on the equalised signals, the phase tracking information, and the resolved data;
• generating an inhibit signal to inhibit updating of the equalisation coefficients, the inhibit signal representing a likelihood of the phase corrected error being accurate, determined according to the phase corrected error, and according to the equalised signals;
• adapting the equalisation coefficients for the equaliser based on the received signals, and based on the phase corrected error;
• and
• inhibiting the adapting according to the inhibit signal.