An information processing apparatus including a noise reduction unit that reduces noise generated from an unmanned aerial vehicle, included in an audio signal picked up by a microphone mounted on the unmanned aerial vehicle, on the basis of state information on a noise source.

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 additional method comprises of incorporating a phase lock loop within the control system configured to determine the frequencies corresponding to the rotors and generate corrective audio signals to achieve active noise cancellation.

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.

The invention comprises of a UAV designed to limit visually contrast and audibility in flight for covert surveillance operations, a method of configuring the UAVs structure to further reduce its visual signature to take account for the atmospheric and terrestrial environment it will operate in and a method of conducting a covert surveillance operation to actively minimise the UAVs visual & auditory signature from the viewpoint of an individual under surveillance. Both passive and active illumination are used to reduce the visual signature of the UAV. The UAV is actively camouflaged using lighting techniques that utilises the limitations of the human visual system and the optical effects of light interacting with the terrain, atmosphere and aircraft. The visual camouflage is directional. The audible signature of the UAV is reduced through the design of the propulsion system and the mode in which the UAV is operated.

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.

A communication method includes obtaining power data associated with a plurality of channels of a frequency band and determining a counter of a set of signal-to-noise ratios (SNRs) for each of the plurality of channels. The set of SNRs is calculated based at least in part on power data for the each of the plurality of channels. The method further includes predicting an error rate for each of the plurality of channels based at least in part on the counter 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.

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.

Disclosed is an aerial vehicle having a reduced noise signature. The aerial vehicle may be a vertical take-off and landing (VTOL) aerial vehicle. The aerial vehicle comprises an airframe and a plurality of rotors operatively coupled with one or more motors. The plurality of rotors may comprise a first, second, third, and fourth rotor. Each of the first, second, third, and fourth rotors may be arranged in a single plane and oriented to direct thrust downward relative to the airframe. In certain aspects, at least two of the plurality of rotors employ a different geometry to generate a targeted noise signature.

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 additional method comprises of incorporating a phase lock loop within the control system configured to determine the frequencies corresponding to the rotors and generate corrective audio signals to achieve active noise cancellation.

An unmanned air vehicle includes a generator that generates a flying force and also generates an air flow, a structural component, a microphone that outputs a first signal, a speaker, and a processor. The processor generates a second signal according to the first signal. The structural component surrounds a noise source of the generator, and includes a through-hole extending in a direction of the air flow. The through-hole is in a direction opposite to the direction of the air flow. An end, in the opposite direction, of the structural component corresponds to an end, in the opposite direction, of the noise source of the generator. An end, in the direction of the air flow, of the structural component extends, in the direction of the air flow, beyond an end, in the direction of the air flow, of the noise source of the generator.