An aerial vehicle is provided including rotor units connected to the aerial vehicle, and a control system configured to operate at least one of the rotor units. The rotor unit includes rotor blades, wherein each rotor blade includes a surface area, and wherein an asymmetric parameter is defined, at least in part, by the relationship between the surface areas of the rotor blades. The value of the asymmetric parameter is selected such that the operation of the rotor unit: (i) moves the rotor blades such that each rotor blade produces a respective vortex and (ii) the respective vortices cause the rotor unit to produce a sound output having an energy distribution defined, at least in part, by a set of frequencies, wherein the set of frequencies includes a fundamental frequency, one or more harmonic frequencies, and one or more non-harmonic frequencies having a respective strength greater than a threshold strength.

An unmanned aircraft includes: a sensor that includes at least a microphone that generates sound data; and a processor. The processor determines the quality of a target sound by use of the sound data generated by the microphone, identifies a sound source direction from the unmanned aircraft to the sound source of the target sound by use of data generated by the sensor, and controls an unmanned aircraft state that is a state of the unmanned aircraft such that a direction of a sound pickup area is aligned with the sound source direction, in accordance with the determined quality. The sound pickup area is a range in which sound pickup quality of the microphone is higher than that of another area.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Systems, methods, and apparatus may actively adjust the position and/or configuration of one or more propeller blades of a propulsion mechanism to generate different sounds and/or lifting forces from the propulsion mechanism.

A computer-implemented method for communication includes obtaining power data associated with a plurality of channels of a frequency band, predicting an error rate for each of the plurality of channels based at least in part on the power data, and selecting a hopset of channels for frequency hopping from the plurality of channels based at least in part on the predicted error rates for the plurality of channels.

A noise cancelation system for an unmanned aerial vehicle may have an audio capture module, a metadata module and a filter. The audio capture module may be configured to receive an audio signal captured from a microphone, e.g., on a camera. The metadata module may be configured to retrieve noise information associated with noise generating components operating on the unmanned aerial vehicle (UAV). The filter may be configured to receive the audio signal and noise information from the audio capture module. The filter also may be configured to retrieve a baseline profile from a database based on the noise information. The baseline profile includes noise parameter to filter out audio frequencies from the audio signal corresponding to the noise generating component. The filter may generate a filtered audio signal for output.

Disclosed is a system, method, and aircraft for controlling acoustic radiation from an aircraft comprising a plurality of rotor systems and a noise controller configured to regulate acoustic radiation from the plurality of rotor systems. The noise controller can be configured to regulate a commanded flight setting from the flight control system and to output a regulated flight setting to the plurality of rotor systems. Based on the regulated flight setting, the plurality of rotor systems are configured to generate, individually and in aggregate, acoustic radiation having a target acoustic behavior. In certain aspects, the noise controller can change the directionality of acoustic radiation from the plurality of rotor systems, or otherwise tune the acoustic radiation to reduce detectability or annoyance.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Systems, methods, and apparatus may actively adjust the position and/or configuration of one or more propeller blades of a propulsion mechanism to generate different sounds and/or lifting forces from the propulsion mechanism.

According to one embodiment, a flying body includes a radar, a supporter, a plurality of rotors supported by the supporter, and a controller. The rotors include a first rotor. The radar is configured to perform a detection operation and a non-detection operation. The controller is configured to perform a first control operation in a first transition from the non-detection operation to the detection operation. The controller is configured to perform a first change in the first control operation to change a rotational speed of the first rotor from a rotational speed of the first rotor in the non-detection operation. The detection operation is performed after the first control operation.

According to one embodiment, a flying body includes a radar, a supporter, a plurality of rotors supported by the supporter, and a controller. The rotors include a first rotor. The radar is configured to perform a detection operation and a non-detection operation. The controller is configured to perform a first control operation in a first transition from the non-detection operation to the detection operation. The controller is configured to perform a first change in the first control operation to change a rotational speed of the first rotor from a rotational speed of the first rotor in the non-detection operation. The detection operation is performed after the first control operation.

An aerial vehicle including a main body having a leading edge. An inlet is recessed aft from the leading edge. Forward protrusions extend from the main body on opposite sides of the inlet. An outlet nozzle is proximate to an aft end. The inlet is in fluid communication with the outlet nozzle. Wings extend from the main body.