Parrot

Parrot Drones

Benoit Pochon

Vu Hoang Co Thuy

Henri Seydoux

Guillaume Pinto

Michael Herve

Phong Hua

Alexandre Briot

Julien De Muynke

Pierre Guiu

Axel Balley

Thomas Dromer

The drone comprises a camera (), an inertial unit () measuring the drone angles, and an extractor module () delivering image data of a mobile capture area of reduced size dynamically displaced in a direction opposite to that of the variations of angle measured by the inertial unit. The module analyses the image data elements of the useful area to assign to each one a weighting coefficient representative of a probability of belonging to the sky, and defines dynamically a boundary of segmentation (F) of the useful area between sky and ground as a function of these weighting coefficients. Two distinct groups of regions of interest ROIs are defined, for the sky area and for the ground area, respectively, and the dynamic exposure control means are controlled as a function of the image data of the ROIs of one of these groups, in particular by excluding the ROIs of the sky area.

Drone with a front-view camera with segmentation of the sky image for auto-exposure control

The headset includes an active noise control, with an internal ANC microphone () placed inside the acoustic cavity () and delivering a signal including an acoustic noise component. A digital signal processor DSP () comprises a feedback ANC branch () applying a filtering transfer function (, H) to the signal delivered by the ANC microphone, and a mixer () for mixing the signal of the feedback branch with an audio signal to be reproduced (M). The headset comprises a movement sensor () mounted on one of the earphones. The DSP comprises an anti-saturation module () for analyzing concurrently i) the signal delivered by the internal microphone () and ii) the signal delivered by the movement sensor (), and verifying whether current characteristics of these signals fulfill or not a set of predetermined criteria. Upstream from the feedback ANC filter (), an anti-saturation filter (, H) is selectively switched as a function of the result of this verification. The filtering of an equalization branch (, H) of the signal to be reproduced (M) is also modified by a similar anti-saturation filter (, H).

ANC noise active control audio headset with prevention of the effects of a saturation of the feedback microphone signal

The method comprises the steps of: a) converting the digital audio signal (PCM) into a voltage signal (V); b) first lowshelf filtering of fixed gain (G); c) calculating a value of excursion (x) of the loudspeaker; d) comparing the excursion with a maximum value and calculating a first gain of possible attenuation (G); e) second lowshelf filtering of gain (G+G) taking into account the first gain of possible attenuation; g) comparing with the maximum saturation or clipping voltage (v) and calculating a second gain of possible attenuation (G); h) third lowshelf filtering gain (G+G+G) taking into account the first and/or second gains of possible attenuation; i) comparing with the maximum saturation or clipping voltage (v) and applying a gain of possible overall attenuation (G); j) optionally compensating for the nonlinearities of the loudspeaker response; and k) reversely converting the signal (V) into a digital audio signal (S) without dimension, for later amplification.

Method for enhancing low frequences in a digital audio signal

The method comprises: a) the emission of an ultrasound burst repeated at a predetermined recurrence frequency; and b) after each emission and for the duration of a time frame (n&#x2212;1, n, n+1, . . . ) separating two consecutive emissions, the reception of a plurality of successive signal spikes appearing in the course of the same frame. These spikes include spurious spikes (E', E&#x2032;, E&#x2032;, . . . ) originating from the emitter of another drone, and a useful spike (E, E, E, . . . ) corresponding to the distance to be estimated. To discriminate these spikes, the following steps are executed: c) for two consecutive frames, comparison of the instants of arrival of the p spikes of the current frame with the instants of arrival of the q spikes of the previous frame and determination, for each of the p.q pairs of spikes, of a corresponding relative time gap; d) application to the p.q gaps determined in step c) of a selection criterion making it possible to retain just a single spike of the current frame; and e) estimation of the distance as a function of the instant of arrival of the spike thus retained.

Method of ultrasound telemetry for drones, with discrimination of spurious echoes emanating from another drone

The method comprises the steps of: filtering the audio signal by means of a lowpass filter () with a cutoff frequency substantially equal to said cutoff frequency (F) of the sound playback device; determining a fundamental frequency for reconstituting from the lowpass filtered audio signal; and generating a harmonic signal (S) associated with said fundamental frequency to be reconstituted. It also comprises the steps of: detecting a time envelope (env(t)) of the lowpass filtered audio signal; adapting the dynamic range of said time envelope (env(t)) as a function of the frequency band under consideration; and reinjecting said harmonic signal in phase into said audio signal by addition after multiplying said harmonic signal (S) with the adapted time envelope (env(t)). The adaptation is performed by compression/expansion of the time envelope with feedback loop control that is adjusted automatically on the value of the envelope as a function of the mean energy of the input signal to a value that maximizes said energy within a defined limit.

Method and a system for reconstituting low frequencies in audio signal

An automatic gain control system applied to a audio signal as a function of the ambient noise, the system comprising: an ambient noise estimator module suitable for establishing a current noise value estimated at least from a signal provided by a microphone; and an automatic gain control module suitable for applying to the audio signal gain of a value that is determined as a function of the current noise value received from the ambient noise estimator module. According to the invention, the ambient noise estimator module comprises an MCRA estimator suitable for establishing the current noise value from a signal provided by the microphone picking up the real noise, the echo of the music, and where appropriate speech. The system also includes a module for estimating the power of the audio signal and suitable for providing the automatic gain control module with a current power value for the audio signal.

Automatic gain control system applied to an audio signal as a function of ambient noise

The device comprises a microphone for detecting a speech signal from a near speaker, and a loudspeaker for reproducing a speech signal from a remote speaker. The processing for canceling the interfering acoustic echo implements an adaptive linear filtering algorithm. Double talk situations are detected by: evaluating an index representative of the convergence or divergence of the algorithm; assessing a predetermined condition for detecting a double talk situation; and if the condition is satisfied, modifying at least one parameter of the algorithm in response to the detection. The representative index may be the norm of the gradient vector describing the adaptation of the filter from one iteration of the algorithm to the next, the conditions being a comparison between the gradient and a threshold. The parameter that is modified double talk situation may be the adaptation stepsize of the algorithm, and also the gain control of an echo suppression stage.

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Paris, France

Benoit Pochon