Digital group delay compensator

A digital group delay compensation system comprising:

• a digital allpass filter that is utilized in an implementation phase;
• and
• a system that generates coefficients for the allpass filter used in the implementation phase such that the overall performance of a system is measured and optimized in a calibration phase;
• wherein the system that optimizes the performance is a closed loop system comprising:
• an optimization element whose output are control variables that it adjusts and whose input is a score of overall system performance based on the output control variables whereby this element adjusts its outputs and examines its input in a manner contrived to maximize the input score;
• a specifications generator that converts the optimizer output and optionally, and the measured uncompensated group delay of the system, into a frequency domain group delay specification;
• an allpass filter fitter element that converts the frequency domain group delay specification into allpass filter coefficients such that the frequency domain group delay specifications are compensated with a high degree of compliance;
• a stimulus generator that can be attached to the channel input in a manner enabling the measurement of the response of the uncompensated system to this known stimulus;
• an allpass filter arrangement containing an allpass filter implementation based on the coefficients provided by the allpass filter fitter element that filters the response of the uncompensated system to a stimulus and produces the response of the compensated system to a stimulus;
• a measurer that makes various parameter measurements on the response of the compensated system to a stimulus;
• and a grading system that converts the various parameter measurements to a score of overall compensated system performance.

A digital group delay compensation system comprising:

• a digital allpass filter that is utilized in an implementation phase;
• and
• a system that generates coefficients for the allpass filter used in the implementation phase such that the overall performance of a system is measured and optimized in a calibration phase;
• whereby optimum performance is not directly based on phase response or group delay characteristic;
• and
• wherein in the calibration phase, the grading system is implemented as a fuzzy logic grading system comprising:
• user defined fuzzy membership sets for the parameters measurements produced by the measurer;
• a user defined fuzzy rule base that provides grading rules based on the membership of the parameter measurements in the fuzzy membership sets;
• and a defuzzification element that produces a single score based on the execution of the rules in the fuzzy rule base.

A digital group delay compensation system comprising:

• a digital allpass filter that is utilized in an implementation phase;
• and
• a system that generates coefficients for the allpass filter used in the implementation phase such that the overall performance of a system is measured and optimized in a calibration phase;
• whereby optimum performance is not directly based on phase response or group delay characteristic;
• and
• wherein in the calibration phase, the allpass filter fitter utilizes the Levenberg-Marquardt algorithm in conjunction with the functions that defines the group delay of allpass filter and the partial derivatives of this function with respect to the filter coefficients and a guess at the coefficient values to calculate filter coefficient values;
• These coefficient values calculated such that the mean-squared error between a group delay specification provided and the function that defines the group delay of an allpass filter evaluated using said coefficients is minimized.