Adaptive feedback system

An adaptive feedback apparatus for reducing distortion produced by an electrical device, comprising:

• an electrical device having an input signal and producing an output signal in response thereto, and
• a feedback coupler means having as its input said input signal, said feedback coupler means including means for combining with said input signal one or more negative feedback signals, the combined signal being provided to the input of said electrical device, and
• an output coupler means having as its input said output signal, said output coupler means including means for dividing said output signal into a primary output signal and one or more secondary output signals, and
• at least one reference signal generating means for generation of one or more reference signals, each of said reference signals being divided into a first and second portion, and
• at least one reference signal combining means for combining the first portion of one of said reference signals with one of said negative feedback signals, and
• at least one combination of one of said reference signal combining means with one of said secondary output signals with a paired set of vector controller means and vector detector means, and
• said vector controller means for adjusting phase of the secondary output signal associated with said combination to produce the negative feedback signal associated with the same combination, said adjustment in accordance with one or more control signals provided by the associated vector detector means, and
• said vector detector means for automatically generating said control signals such that a selected spectral portion of said secondary output signal is negatively fed back thereby resulting in suppression of a corresponding spectral portion of said primary output signal.

A method for cancelling a selected signal from a closed-loop control system, the closed-loop control system comprising an input signal, an element modifying the input signal, an output signal, and a feedback path, the method comprising the steps of:

• providing a selected signal to the feedback path;
• comparing the selected signal with a feedback signal derived from the feedback path;
• deriving from the comparison one or more control signals;
• applying the control signals to the selected signal, thereby deriving a cancellation signal;
• and
• feeding back a combination of the feedback signal and the cancellation signal into the modifying element.

A method for cancelling a selected signal from a closed-loop control system, the closed-loop control system comprising an input signal, an element modifying the input signal, an output signal and a feedback path, the method comprising the steps of:

• providing a selected signal to the feedback path;
• comparing the selected signal with a feedback signal derived from the feedback path;
• deriving from the comparison one or more control signals;
• applying the control signals to the feedback signal, thereby substantially cancelling the selected signal from the feedback signal;
• and
• after the selected signal has been cancelled from the feedback signal in the preceding step, feeding back the feedback signal into the modifying element.

An apparatus for eliminating a selected signal from a feedback path of a closed-loop control system, the closed loop control system comprising an input signal, an element that modifies the input signal, an output signal and the feedback path, the apparatus comprising:

• means for deriving one or more control signals by comparing the selected signal with a feedback signal derived from the feedback path;
• means for generating a cancellation signal by applying the control signals to the selected signal;
• signal adding means for generating a combination of the cancellation signal and the feedback signal;
• signal coupler means for feeding back the combination of the cancellation signal and the feedback signal into the modifying element.

An apparatus for eliminating a selected signal from a feedback path of a closed-loop control system, the closed loop control system comprising an input signal, an element that modifies the input signal, an output signal and the feedback path, the apparatus comprising:

• means for comparing the selected signal with a feedback signal derived from the feedback path;
• means for deriving from the comparison one or more control signals;
• signal cancellation means for applying the control signals to the feedback signal, thereby substantially cancelling the selected signal from the feedback signal;
• and
• signal coupler means, coupled to the signal cancellation means, for feeding back the feedback signal into the modifying element.

An apparatus for eliminating a selected signal from a feedback path of a closed-loop control system, the close loop control system comprising an input signal, an element that modifies the input signal, an output signal and the feedback path, the apparatus comprising:

• means for comparing the selected signal with a feedback signal derived from the feedback path;
• means for deriving from the comparison one or more control signals;
• signal cancellation means for applying the control signals to the feedback signal, thereby substantially cancelling the selected signal from the feedback signal;
• and
• signal coupler means, coupled to the signal cancellation means, for feeding back the feedback signal into the modifying element.