Abstract: An adaptive noise rejection method and apparatus. An information signal having an information component and a repetitive noise component having a varying characteristic frequency is delayed the information signal by a reference delay time that is equal that is equal to a predetermined number of periods of the characteristic frequency to form a delayed information signal. The delayed information signal is subtracted from the information signal to form a processed information signal in which the information component is substantial and the noise component is negligible. The amplitude of the noise component of the processed information signal is constantly monitored. The delay of the information signal is varied as the characteristic frequency of the noise component changes so as to maintain the amplitude of the noise component of the processed information signal at a predetermined level.

Abstract: An adaptive radio frequency (RF) electromagnetic interference rejection system and method. An RF information signal having an information signal component and an interfering electromagnetic signal component that has a varying characteristic frequency is delayed by a reference delay time that is equal that is equal to a predetermined number of periods of the characteristic frequency to form a delayed RF information signal. The delayed RF information signal is subtracted from the non-delayed RF information signal to form a processed RF information signal in which the information component is substantial and the interfering electromagnetic signal component is negligible. The amplitude of the interfering electromagnetic signal component of the processed RF information signal is constantly monitored.

Abstract: An adaptive noise rejection method and apparatus. An information signal having an information component and a repetitive noise component having a varying characteristic frequency is delayed the information signal by a reference delay time that is equal that is equal to a predetermined number of periods of the characteristic frequency to form a delayed information signal. The delayed information signal is subtracted from the information signal to form a processed information signal in which the information component is substantial and the noise component is negligible. The amplitude of the noise component of the processed information signal is constantly monitored. The delay of the information signal is varied as the characteristic frequency of the noise component changes so as to maintain the amplitude of the noise component of the processed information signal at a predetermined level.

Abstract: An adaptive noise rejection method and apparatus. An information signal having an information component and a repetitive noise component having a varying characteristic frequency is delayed the information signal by a reference delay time that is equal that is equal to a predetermined number of periods of the characteristic frequency to form a delayed information signal. The delayed information signal is subtracted from the information signal to form a processed information signal in which the information component is substantial and the noise component is negligible. The amplitude of the noise component of the processed information signal is constantly monitored. The delay of the information signal is varied as the characteristic frequency of the noise component changes so as to maintain the amplitude of the noise component of the processed information signal at a predetermined level.

Abstract: An apparatus and method removes repetitive background noise from an information signal originating from a first source, such as a microphone. The noise originates from a second source, such as a siren, and is picked up by the first source along with the information. The noise signal has a characteristic frequency and associated period. The information signal is delayed for a selected period of time based on the characteristic frequency of the repetitive noise signal and forms a phase-shifted or delayed information signal. The delayed information signal is processed with a substantially non-delayed information signal and forms a processed information signal in which the information component is substantial and the noise component is negligible.