ALEXANDRIA, Va., Aug. 18 -- United States Patent no. 12,711,937, issued on Aug. 18.
"Rotor craft noise cancellation system and method" was invented by Alan Richard Greenberg (Los Angeles).
According to the abstract* released by the U.S. Patent & Trademark Office: "Rotor noise cancellation through the use of mechanical means for a personal aerial drone vehicle. Active noise cancellation is achieved by creating an antiphase amplitude wave by modulation of the propeller blades, by utilizing embedded magnets through an electromagnetic coil encircling the propeller blades. A noise level sensor signals the rotor control system to adjust the frequency of the electromagnetic field surrounding the rotor and control the speed of the rotor. An addit...