ACTIVE NOISE CANCELLATION OF EQUIPMENT FAN NOISE ON AIRCRAFT

The improved active noise cancellation system for forced air heating or cooling systems onboard aircraft employs a duct having a proximal end coupled to the fan unit to entrain the airflow stream in the direction of a distal end of the duct. A reference sensor is positioned within the proximal end o...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser:	WANG, Tongan, BOHANAN, Scott, JORDAN, Jim
Format:	Patent
Sprache:	eng ; fre ; ger
Schlagworte:	ACOUSTICS ACOUSTICS NOT OTHERWISE PROVIDED FOR BLASTING HEATING LIGHTING MECHANICAL ENGINEERING METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING,NOISE OR OTHER ACOUSTIC WAVES IN GENERAL MUSICAL INSTRUMENTS NON-POSITIVE DISPLACEMENT PUMPS PHYSICS POSITIVE DISPLACEMENT MACHINES FOR LIQUIDS PUMPS FOR LIQUIDS OR ELASTIC FLUIDS SOUND-PRODUCING DEVICES WEAPONS
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Beschreibung
Zusammenfassung:	The improved active noise cancellation system for forced air heating or cooling systems onboard aircraft employs a duct having a proximal end coupled to the fan unit to entrain the airflow stream in the direction of a distal end of the duct. A reference sensor is positioned within the proximal end of the duct. A means is provided for injecting an audio frequency control signal into the airflow stream in a manner that does not substantially impede the airflow stream. An error sensor is positioned at the distal end of the duct where it is responsive to sounds carried by the airflow stream, including the audio frequency control signal. An electronic circuit coupled to the reference sensor and to the error sensor supplies a noise abating control signal to energize the control transducer and thereby substantially reduce at least one noise harmonic of the fan unit through destructive interference.