Acoustic tracking device for flying objects

Abstract

Acoustic locating and tracking device for flying objects, comprising two parabolic reflectors (1a, 1b), each with two microphones (2a-2d) for detecting acoustic signals, a mechanical swiveling device (3), a control unit (4) and an evaluation unit (5), characterized in that by comparing the four microphone signals both a horizontal and a vertical direction angle is calculated and a three-dimensional vector to the sound source is determined from this.

Description

Technical field:

[0001] The invention relates to the identification, location, and tracking of flying objects, in particular unmanned aerial vehicles (drones), using directional microphones and signal processing units. It is suitable for both stationary and mobile applications. State of the art:

[0002] Known acoustic drone detection systems mostly use microphone arrays that estimate directions using complex digital signal processing. Parabolic microphones have so far primarily served to focus sound during recording.

[0003] A combination of a mechanically swiveling, parabolic receiving unit with four microphones for simultaneous horizontal and vertical direction determination and subsequent automatic tracking of the sound source is not disclosed in the known prior art. Purpose of the invention:

[0004] The aim of the invention is to provide a compact, passive localization and tracking system that can accurately determine both the horizontal and vertical direction of a flying object by means of acoustic measurement and actively track this direction.

[0005] Additionally, it should be possible to identify the flying object using a stored acoustic signature.

[0006] In conjunction with other similar systems, precise position determination, including location and altitude, as well as tracking, is possible. Solution to the problem:

[0007] This task is solved by an acoustic locating device with four microphones in combination with a mechanical swiveling device and a software-supported evaluation unit.

[0008] The device includes: • two parabolic reflectors (1a, 1b), • Two microphones per reflector (2a, 2b for the left, 2c, 2d for the right reflector), arranged in a slightly vertically offset position relative to each other, • a mechanical swiveling device (3) for horizontal and vertical movement, • a control unit (4) for acquiring, synchronizing and processing the signals from the four microphones, • an evaluation unit (5) with algorithms for direction calculation and aircraft tracking, • and a database (6) of stored acoustic signatures for identification.

[0009] The four microphones together form a stereoscopic vertical arrangement: • The two upper microphones (2a, 2c) primarily serve for horizontal direction determination (azimuth), • The two lower microphones (2b, 2d) provide additional time and phase information for determining the elevation angle.

[0010] A precise three-dimensional direction vector (azimuth, elevation) is calculated through cross-correlation and time difference analysis between the channels.

[0011] This vector is used to control the swivel mechanism, allowing the device to automatically track the flying object ("tracking mode").

[0012] The motor can be aligned to the maximum signal level or follow a calculated trajectory.

[0013] Additionally, a spectral analysis of the received signals is performed.

[0014] A comparison with the signature stored in the database enables the classification of the flying object (e.g., multicopter, fixed-wing aircraft, helicopter).

[0015] The system can be combined with one or more identical devices to determine the exact position and altitude of the object via triangulation. Advantages of the invention • High directional resolution in azimuth and elevation through four-channel parabolic arrangement. • Active automatic tracking of the sound source. • Passive, noiseless system - no active emission. • Expandable through multi-device networks for 3D positioning. • Identification through signature comparison. • Suitable for mobile and stationary applications. • Relatively inexpensive to manufacture compared to conventional radar systems Figure 1: 1 Two parabolic halves (1a, 1b) side by side on a support plate. 2 Two microphones per reflector (2a-2d), vertically offset. 3 Mechanical swivel axis for horizontal (3a) / vertical (3b) movement. 4 Control unit (4) 5 and evaluation unit (5) in the housing. 6 ports for output / communication / PC(6) Figure 2 (block diagram): 1 Four microphones (2a-2d inFig. ) 2 preamplifiers & A / D converters (synchronized) 3 Control unit (TDOA calculation, direction vector) 4 Motor control (swivel control horizontal and vertical) 5 Signature analysis module (spectral comparison) 6 Database of acoustic signatures (6) 7 Display / Alarm output / Further processing

Claims

Acoustic locating and tracking device for flying objects, comprising two parabolic reflectors (1a, 1b), each with two microphones (2a-2d) for detecting acoustic signals, a mechanical swiveling device (3), a control unit (4) and an evaluation unit (5), characterized in that by comparing the four microphone signals both a horizontal and a vertical direction angle is calculated and a three-dimensional vector to the sound source is determined from this. Locating device according to claim 1, characterized in that the control unit (4) controls the swivel device (3) in such a way that the device is automatically aligned to the determined direction and is tracked to follow the flying object. Tracking device according to one of the preceding claims, characterized in that the evaluation unit (5) contains a database (6) of stored acoustic signatures, on the basis of which the type of flying object is identified. Tracking device according to one of the preceding claims, characterized in that several devices can be networked together to enable position and altitude determination of the flying object by crossing the direction vectors. Tracking device according to one of the preceding claims, characterized in that the device can be mounted both stationary and operated mobile. Locating device according to one of the preceding claims, characterized in that the signal processing is carried out by a computer-aided method with feature extraction, cross-correlation and classification algorithm. Tracking device according to one of the preceding claims, characterized in that the device can supplement conventional systems such as radar systems to more precisely determine and classify positions. Tracking device according to one of the preceding claims, characterized in that the system can be extended by components of visual detection such as zoom camera and, if necessary, combating e.g. laser or masker.

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