DRONE DETECTION DEVICE FOR DRONES FLYING OVER OR APPROACHING SENSITIVE SITES

Abstract

The invention relates to a drone detection device comprising: - an antenna for capturing an electromagnetic signal (1), - a system (2) for periodically searching for the presence of a signal having a predetermined frequency within the captured signal, and for isolating this signal, - a module for extracting synchronization information from the isolated signal, - a control unit (6) for the synchronization information extracted from the isolated signal and for identifying the isolated signal as a stable synchronized signal when the extracted synchronization information has predetermined characteristics, - means for communicating (9, 11, 12) information for detecting a stable synchronized signal when the control unit has identified a stable synchronized signal.

Description

[001] The invention relates to a device for detecting drones flying over or approaching sensitive sites.

[002] In recent years, small drones have become increasingly attractive and accessible in terms of purchase price, maneuverability, and availability to a wide public no longer consisting solely of professionals but also of amateurs.

[003] Although their use in a territory is regulated by the corresponding national law relating to the design and use of civil aircraft operating without any person on board (see for example for the French territory, the decree of 11 April 2012), these drones are sometimes used illegally and for malicious purposes such as the violation of privacy, industrial espionage or intrusion into sensitive sites.

[004] Consequently, the monitoring of sensitive sites such as public spaces, private properties and industrial sites, particularly those at risk such as nuclear power plants, has become a major concern for those responsible for ensuring the safety of people and property or respecting privacy. STATE OF THE TECHNIQUE AND ITS DISADVANTAGES

[005] Solutions have been put in place to detect drones not complying with the instructions for flying over or approaching sensitive sites.

[006] For example, US patent 9,275,645 filed in the name of DRONESHIELD describes a system, a method, and an apparatus for drone detection. This detection is based on the reception of an acoustic signal by a microphone in the apparatus and the recording, via a sound card, of a digital sound sample of the detected signal, the digital sound sample having a predetermined duration. The method also includes the processing, via a processor, of the digital sound sample into a frequency spectrum. The method further includes comparing the reconstructed spectrum to a pre-recorded spectral signature stored in a database, corresponding to a flight characteristic of a drone model. The method also includes transmitting an alert via the processor.

[007] However, these detection systems, methods, and devices are not entirely satisfactory because they are based on comparing a spectrum reconstructed from the detected sound signal with pre-recorded spectral signatures, whereas each drone emits a unique sound signal depending on its constituent elements, structure, and flight pattern. Thus, a newly developed drone may emit a sound signal that is unknown to the database of pre-recorded spectral signatures and will not be detected. Furthermore, a known drone may have some of its constituent elements modified and emit a new sound signal compared to the pre-recorded signatures. In addition, a known drone, whose spectral signature is indeed contained in the database, may fly over or approach the sensitive site without emitting any sound, for example, by hovering, and will not be detected by this system.

[008] The invention aims to remedy these problems by proposing a device, a method for detecting drones which is said to be passive because it does not emit signals likely to disrupt the installations of the site to be protected from any intrusion, and does not cause the drone to fall, while presenting a detection reliability superior to that of existing devices and methods. SUBJECT OF THE INVENTION

[009] To this end, and according to a first aspect, the invention proposes a drone detection device comprising: an antenna for capturing an electromagnetic signal a system for periodically searching for the presence of a signal with a predetermined frequency within the captured signal, and for isolating that signal an isolated signal synchronization information extraction module a control unit for synchronization information extracted from the isolated signal and for identifying the isolated signal as a stable synchronized signal when the extracted synchronization information exhibits predetermined characteristics means of communicating information for detecting a stable synchronized signal when the control unit has identified a stable synchronized signal

[0010] The invention may also have other interesting aspects: Most advantageously, the signal with a predetermined frequency to be searched for and isolated is of the video type and the system for periodically searching for the presence of a signal and isolating that signal is of the video scanner type. According to one embodiment, the predetermined frequency is between 0.9 and 6 GHz. Ideally, the control unit includes a time-counting module for even and odd frames, an internal clock, and a detection module configured to, within a given time window, take into account the number of even and odd frames counted by the counting module, and if the number of even and odd frames are identical, to output the detection information of a stable video signal In one interesting embodiment, the time window has a fixed duration or a variable duration determined by the detection module. Preferably, the detection module includes means for transmitting a serial frame when the detection information of a stable video signal is transmitted, and the device includes a communication interface with a nearby terminal, of the USB or serial port type, connected to the detection module. The device may include a proximity terminal connected to the communication interface and equipped with means for time stamping and / or recording in a Serial frame file corresponding to the detected stable video signal. The device may include a GSM module connected to the detection module and capable of communicating an SMS alarm message to a remote mobile terminal when the detection information of a stable video signal via a telecommunications network 5 is emitted. The device may include a logic output controlling a relay of the device to trigger a visual or audible alarm of the device. The device may include, between the video scanner and the extraction module, a first video amplifier of the video signal isolated by the scanner. 10 - The device may include, downstream of the scanner, a video output for viewing the Isolated video signal, via an external monitor. In addition, the device may include, between the first video amplifier and the video output, a second video amplifier for the isolated video signal amplified by the first amplifier. "

[6011] The invention also relates to a method for detecting the presence of a drone near or flying over a sensitive site, implemented by at least one of the above devices.

[0012] This process mainly comprises the steps of: capture of an electromagnetic signal by an antenna periodic search for the presence of a signal with a predetermined frequency 20 within the captured signal, and isolation of this signal by a dedicated system extraction of synchronization information from the isolated signal by a dedicated module control of synchronization information extracted from the isolated signal and identification of the isolated signal as a stable synchronized signal when the extracted synchronization information has characteristics predetermined by a dedicated unit communication of information regarding the detection of a stable synchronized signal by the control unit.

[6013] BRIEF DESCRIPTION OF THE FIGURES

[0014] Other objects and advantages of the invention will become apparent in the following description, made with reference to: Figure 1, which represents a functional schematic view of the device according to the invention Figure 2, which represents, in the form of a graph over time, the profile of an ODD / EVEN signal from the synchronization extractor DETAILED DESCRIPTION OF THE FIGURES In relation to Figure 1, a drone detection device according to the invention is described, 15 from a synchronized data stream emitted by the drone when it approaches or flies over the sensitive site to be monitored. This stream is preferably a video stream which typically has a synchronized profile whose repetitive sequence is recognizable and detectable by a video scanner system. To this end, the device according to the invention is in the form of a housing comprising: 20 - an omnidirectional antenna for capturing electromagnetic signals 1 a video scanner 2 periodically searching, among the electromagnetic signals captured by antenna 1, for the presence of a video signal exhibiting a predetermined frequency, capable of isolating and transmitting this signal to: An extraction module (“sync extraction” in Figure 1) allows the extraction of synchronization information from the video signal isolated by the scanner and amplified by a video signal amplifier 4, and is in the form of an integrated circuit. This extraction module 3 can use several synchronization information: Vsync (vertical synchronization or “top” frame), Hsync (horizontal synchronization or “top line”), Odd / Even (even or odd frame) 5 shown in Figure 2 a control unit 6 comprising a time-counting module 7 for even and odd frames, an internal clock (not shown), and a detection module 8 configured to, within a given time window, take into account the number of even frames and the number of odd frames counted by the counting module 7, and if the number of even frames and the number of odd frames are identical, to transmit the detection information of a stable video signal. The time window during which the odd and even frames are counted may be of fixed duration or of variable duration set by the detection module 8 Thus, control unit 6 counts, within a fixed time window (for example, four seconds), the number of even and odd frames (images). If the number of even frames is the same as the number of odd frames (50 frames per second), control unit 6 considers the image stable and the detected video signal to be a signal that poses a risk to the monitored site, and an alarm is triggered. The detected stream is a video stream emitted by a camera mounted on the drone to be detected when it is equipped with one and when it is activated and in video stream emission mode. It is generally transmitted at a frequency between 0.9 and 6 GHz, preferably 1.2, 2.4, or 5.8 GHz, and the scanner 2 used in the device according to the invention will be calibrated to detect video streams whose frequency falls within this range or whose frequency is equal to or around (within a 1% to 10% difference) any one of the three aforementioned specific values, or only one of them. The stream frequency may be adjustable. video to be detected by the video scanner. The alarm advantageously allows the activation of a logic output controlling a relay 9 (allowing an audible or visual alert to be triggered) and a galvanically isolated power MOSFET transistor. This alarm also triggers the sending of an SMS via a GSM / GPRS modem 11. A serial frame is also transmitted to a PC via USB and RS232 interfaces, to which a desktop or mobile computer can be connected. These frames can therefore easily be time-stamped and recorded in a file to constitute evidence of the drone's approach to or overflight of the sensitive site. After a delay of 10 seconds, the detector is reset and the periodic search with the video scanner resumes. A 15" LCD display allows you to see which operating phase the device is in (detection in progress, alarm triggered, reset, standby or off). Ideally, in addition to periodic video scanning of signals detected by the antenna, an additional scanner functionality could be developed and used to guarantee the quality of the composite video signal coming out of the scanner, before starting any processing of synchronization extraction, frame counting, detection and emission of an alarm. To this end, the video scanner 2 was modified to utilize its audio output (alarm), indicating that detection has occurred and that a video signal of satisfactory quality (according to predetermined amplitude and stability criteria) is available at the output. An electronic interface was created to generate a logic signal from this alarm (audio output 21 of scanner 2). This logic output can be connected via a connection 22 to the control unit 6, which, when this audio output is activated to signify the detection of a strong and stable composite video signal, will, via an analog switch 23, close a switch 24 interposed between the video scanner 2 and the first amplifier 4, thus allowing the transmission of a high-quality composite video signal to the subsequent processing modules. signal (amplification 4, extraction synchronization 3, control unit 6. Furthermore, the control unit and the card that constitutes it can advantageously include many possibilities (analog inputs, pwm outputs, I2C bus,...) for the development of additional functionalities. 5 In addition, the power supply for the device according to the invention can be provided via mains power within a fixed building. According to an advantageous implementation, the device could instead be made mobile by being powered by: a power source mounted on a moving element or vehicle, such as a lighter 10 cigars from a motor vehicle or from a portable energy source attached to or integrated into the casing, such as a battery or photovoltaic panels Ideally, the video signal isolated by scanner 2 and amplified by the first video amplifier 4, can be transmitted to a video output 16 possibly via a second amplifier 17, to view the isolated video signal 15, by an external monitor 18.

Claims

DEMANDS 1. Passive drone detection device comprising: an antenna for capturing an electromagnetic signal (1) a system (2) for periodically searching for the presence of a signal having a predetermined frequency within the captured signal, and for isolating this signal an isolated signal synchronization information extraction module (3) a control unit (6) for extracting synchronization information from the isolated signal and identifying the isolated signal as a stable synchronized signal when the extracted synchronization information has predetermined characteristics means of communication (9, 11, 12) of a detection information of a stable synchronized signal when the control unit has identified a stable synchronized signal 2. Device according to claim 1, wherein the signal having a predetermined frequency to be searched for and isolated is of the video type and the system for periodically searching for the presence of a signal and isolating this signal is of the video scanner type (2).

3. Device according to claim 2, wherein the predetermined frequency is between 0.9 and 6 GHz.

4. Device according to claim 2 or 3, wherein the control unit (6) comprises an even and odd frame time counting module (7), an internal clock, and a detection module (8) configured to, within a given time window, take into account the number of even frames and the number of odd frames counted by the counting module, and if the number of even frames and the number of odd frames are identical, to emit the detection information of a stable video signal.

5. Device according to claim 4, wherein the detection module (8) includes means for transmitting a serial frame when the detection information of a stable video signal is transmitted, and the device includes a communication interface with a nearby terminal (13), of the USB or serial port type, connected to the detection module (8).

6. Device according to claim 5, comprising a proximity terminal (13) connected to the communication interface (12) and provided with means for time-stamping and / or recording in a file the serial frame corresponding to the stable video signal detected.

7. Device of any one of claims 4 to 6, comprising a GSM module (11) connected to the detection module (8) and capable of communicating an SMS alarm message to a remote mobile terminal via a telecommunications network when the detection information of a stable video signal is emitted.

8. Device according to any one of claims 4 to 7, comprising a logic output controlling a relay (9) of the device for triggering a visual or audible alarm of the device.

9. Device according to any one of claims 2 to 8, comprising between the video scanner (2) and the extraction module (3), a first video amplifier (4) of the video signal isolated by the scanner (2).

10. Device according to any one of claims 2 to 9, comprising downstream of the scanner (2), a video output (16) for viewing the isolated video signal, by an external monitor (18).

11. Device according to claim 9, comprising between the first video amplifier (4) and the video output (16), a second video amplifier of the video signal (17) isolated and amplified by the first amplifier (4).

12. A method for passively detecting the presence of a drone near or flying over a sensitive site, comprising the following steps: • capture of an electromagnetic signal by an antenna • Periodic search for the presence of a signal with a predetermined frequency within the captured signal, and isolation of this signal by a dedicated system • Extraction of synchronization information from the isolated signal using a dedicated module • control of synchronization information extracted from the isolated signal and identification of the isolated signal • communication of detection information of a stable synchronized signal by the control unit.

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