Method for locating sound event

Abstract

The invention relates to a method for locating a sound event (S) by measuring at least three receivers (2, 3), in particular a receiver (2, 3) having a known position or equipped with a geolocation module configured to provide the position of the receivers (2, 3), the reception time at which signals representative of sound waves emitted during the sound event (S) are received, the method comprises the following steps: a) determining, for each receiver (2, 3), a reception time of a signal, referred to as a "sound signal", representative of a wave emitted during a sound event (S); b) calculating, for at least two pairs of receivers (2, 3), a difference in distance between a receiver (2, 3) in each pair of receivers and the sound event (S) based on the reception time of the sound signal; and c) determining the position of the sound event (S) by trilateration on the basis of e one or more differences of the calculated distances and the position of the receiver (2, 3) at the corresponding reception time.

Description

Technical Field

[0001] The present invention relates to the field of locating sound events such as gunshot or explosions based on the acoustic detection of such events. Background Art

[0002] There are many applications in which it is desirable to precisely determine the location of a sound event.

[0003] For example, in the security sector, there has been a growing demand over the years for means to locate gunfire, in particular in situations of attack, armed conflict, humanitarian intervention in unstable areas, or even during hunting trips.

[0004] To address this, some systems have been created, but these systems are not designed to be easily usable by the general public on mobile devices.

[0005] US Patent 7,599,252 discloses a system for locating gunshot sounds, which determines the location of a location based on information related to the angle of arrival and the time of arrival of sound waves at an acoustic sensor.

[0006] US Patent 8,050,141 also discloses a system and method for estimating the trajectory of a bullet based on the acoustics of the shock waves generated as the bullet passes through the air.

[0007] However, both solutions are complex and expensive to implement.

[0008] Thus, there is a need to benefit from a system that facilitates the location of sound events without losing the reliability of the location.There is also a need for a system for locating sound events that is easily transportable. Summary of the Invention

[0009] The present invention aims to meet this need and achieves this object by means of a method for locating a sound event by measuring the time of reception of a signal representing a sound wave emitted during the sound event using at least three receivers, in particular receivers whose positions are known or receivers equipped with a geolocation module configured to provide the positions of the receivers, said method comprising the following steps:

[0010] a) determining, for each receiver, the time of reception of a signal representing waves emitted during a sound event (referred to as a "sound signal");

[0011] b) calculating, for at least two pairs of receivers, a distance difference between the receivers in each pair of receivers and the sound event based on the reception time of the sound signal;

[0012] c) determining the position of the sound event by trilateration based on the calculated difference or differences between the distances and the position of the receiver at the corresponding reception time.

[0013] With the aid of the method according to the invention, the localization of a sound event can be achieved simply and precisely.

[0014] The sound event may correspond, for example, to the firing of a gun or the impact of such a firing, an explosion, thunder, an alarm, the noise of an accident, or any other event that generates a sound signal.

[0015] The gun may correspond to a rifle, a shotgun, a machine gun, a howitzer, a mortar, a cannon, and this list is by no means limiting. The sound waves emitted by the weapon preferably correspond to muzzle waves of a gun (cannon).

[0016] The method may include displaying the location of the sound event on a viewing device (e.g., a screen) such as a computer, a phone, or an augmented reality headset.

[0017] The method may include storing the location of the sound event and the noise perceived by the receiver on a digital storage unit.

[0018] The method may further comprise storing the time of reception of the sound signal by the receiver in a storage unit, in particular together with the position of the receiver at the time of reception of the sound signal, and may further comprise storing any sound picked up by the receiver.

[0019] The method may comprise a step involving electronically signing the location of the sound event and / or data used to calculate the location of the sound event, in particular the reception times of the sound signals and / or the location of the receiver at these reception times.

[0020] The storage unit may be a server remote from the receiver.

[0021] In some embodiments, the position determination in step c) is performed by one of the receivers.

[0022] In some embodiments, the position determination in step c) is performed by a server remote from the receiver.

[0023] Step a) may be performed by a remote server for at least one of the receivers, wherein the sound signal is retransmitted by the receiver to said server.

[0024] Step b) may be performed by a remote server for at least one of the receivers, wherein the reception time is resent by the receiver to said server.

[0025] As an alternative embodiment, steps a) and / or b) are performed by at least one of the receivers.

[0026] At least one of the receivers can be portable. The use of portable receivers allows the system to be deployed at various locations without requiring extensive coordination. In particular, the system can be used in a mobile manner, for example, with teams moving around an operational area at a distance from one another.

[0027] The steps of the method may be implemented using at least one fixed receiver arranged at height, in particular on top of a structure such as a tower or pylon, wherein the position of the fixed receiver or receivers is known.

[0028] The method may comprise querying weather data in the vicinity of the receiver, for example via a digital network. This may allow the positioning to be adjusted by taking into account the local propagation speed of sound, thereby enabling the accuracy of locating sound events to be improved, for example using an iterative method.

[0029] When receiving the sound signal, one or more receivers may be stationary. As an alternative embodiment, one or more receivers may be moving when receiving the sound signal. In this case, calculation step b) is implemented so as to take into account the Doppler effect, in particular using information related to the direction and standard of the speed of the receiver at the time of reception. This allows the recognition of the sound signal of one or more moving receivers to be adjusted, which in turn allows the signal representing the waves emitted during the sound event to be standardized. Information related to the speed of the receiver, including the direction of movement of the receiver, is advantageously stored together with the data used to determine the position of the sound event.

[0030] The method may comprise broadcasting an action to be performed following step c) of determining the location of the sound event.

[0031] The broadcasting can be performed by transmitting an acoustic signal and / or by displaying on a screen, in particular a screen of one of the receivers.

[0032] The action to be performed may be a message to seek shelter, in particular broadcast via a loudspeaker (eg a siren), and / or a message to a group of mobile phones, for example by using a crowd warning and information network (eg the FR Alert Network or similar).

[0033] The action to be performed may also involve notifying emergency services, such as the police, firefighters, civil protection, or even the military.

[0034] The action to be performed may involve illuminating the identified location with a searchlight.

[0035] The action to be performed may relate to the location identified by the blank record.

[0036] The action to be performed may involve directing a light beam, such as a beam of a laser and / or a searchlight, towards the sound event S.

[0037] The action to be performed may involve, for example, photographing the location where the sound event occurred using a camera, preferably a camera equipped with a telephoto lens.

[0038] The action to be performed may involve directing a reconnaissance drone to the location of the incident.

[0039] Of course, the method may comprise multiple broadcasts of actions to be performed following step c) of determining the location of the sound event.

[0040] The method can also be used to correlate two sound events, such as the gun / muzzle noise of a gun on the one hand and the impact noise of one or more projectiles on the other hand, especially if the ballistic characteristics of the weapon that may have been used are known, even if the noise of the impact is too low to be heard by multiple receivers.

[0041] When at least 4 receivers, preferably at least 6 receivers are used, the method may comprise the step of selecting a receiver from among the receivers that receive the sound signal.

[0042] System for detecting and localizing sound events

[0043] Independently or in combination with the above aspects, according to another aspect of the present invention, another object of the present invention is to provide a system for detecting and locating sound events, the system comprising:

[0044] - at least three receivers, each receiver being arranged to receive at least one signal representative of sound waves emitted during a sound event (referred to as "sound signal"),

[0045] Each receiver is equipped with at least one microphone and comprises:

[0046] o a positioning module that stores the location of the receiver or a geolocation module configured to provide the location of the receiver; and

[0047] ○Select from the following modules:

[0048] ■ a noise recognition module configured to recognize a sound signal and determine a reception time of the signal by a receiver; or

[0049] ■ a retransmission module configured to transmit a signal representing the sound to the remote noise recognition module in an instantaneous or delayed manner;

[0050] - a processing device configured to:

[0051] o receiving data associated with each receiver (referred to as "receiver data"), the receiver data including a receipt of the sound signal or a time at which the receiver received the sound signal, and the location of the receiver at the time of receipt;

[0052] o calculating a date of a reception time of the sound event, if not already calculated, and then calculating, for at least two pairs of receivers, a difference in distance between the event and each receiver in each pair of receivers based on the reception time at which the receivers received the sound signal;

[0053] o Based on the calculated difference in distances and the position of the receiver, the location of the sound event is determined by trilateration.

[0054] A suitable noise recognition module is the OSSR “Orelia Sound Source Recognition” software sold by the company Orelia and described in application FR 2 923 043 .

[0055] The computers used to determine the time of receipt of the sound signal may have synchronized clocks or a common clock.

[0056] The system may be configured to verify the calculated location of the sound event using an electronic signature.

[0057] The system can be configured to store the calculated position of the sound event, in particular the verified position, in a storage unit of the system, in particular using the processing means, and / or to transmit the position to a remote server for storage therein. The calculated position of the sound event is preferably stored and / or transmitted together with information related to the receiver data used for the calculation of the position.

[0058] The system may include viewing devices configured to display the location of the sound event, wherein the viewing devices particularly include augmented reality headsets.

[0059] Geolocation module

[0060] The geolocation module may comprise or include a GNSS "Global Navigation Satellite System" satellite navigation system, in particular a GPS type system. The positioning module may include a GSM "Global System for Mobile" positioning system.

[0061] The geolocation module may comprise an indoor positioning system, in particular one using Wi-Fi (Wireless Fidelity), UWB “Ultra-Wideband” or EMF “Electromagnetic Field”, or as described in patent FR 3120134 A1 entitled “Method for geolocating a receiver”.

[0062] The positioning module may comprise a positioning system using long waves with a frequency less than 1 GHz, as described in French patent application FR2101708.

[0063] Receiver

[0064] At least one receiver, and preferably all receivers, can be selected from a smartphone, a drone equipped with a microphone, a headset equipped with a microphone, a pair of smart glasses equipped with a microphone, a smartwatch equipped with a microphone, a surveillance camera equipped with a microphone, a base of an alarm unit equipped with a microphone, a home automation unit equipped with a microphone, a connected vibration sensor, a voice assistant, a connected car equipped with a microphone in the passenger compartment, or any other device containing a microphone, this list being in no way limiting. In particular, different receivers can be used, such as a phone and a drone, or even several different phone models. Thus, the present invention allows maximizing the number of potential receivers without significantly increasing the cost of the system.

[0065] The system may comprise one or more fixed receivers arranged at height, in particular on top of a structure such as a tower or a pylon, wherein the position of the one or more fixed receivers is known.

[0066] A fixed receiver may not have a geolocation system whose position is known, especially since it is not moving.

[0067] The receivers could be a group of networked surveillance cameras installed in a city or neighborhood, used to detect noise disturbances or gunfire, particularly to quickly locate the location of an intervention for law enforcement agencies.

[0068] The receiver may be a set of equipment consisting of at least one mobile phone and two receivers with known positions, particularly for military or security applications.

[0069] For example, the receiver may be a group of at least two drones and a mobile phone used to monitor an area for armed fugitives.

[0070] The receiver may be a set of three microphones equipped with a radio wave transmitter.

[0071] The receiver can be configured to store the calculated position of the sound event (in particular a verified position) in a storage unit of the receiver and / or to send the position to a remote server for storage therein, wherein the calculated position of the sound event is preferably stored and / or sent together with information related to the receiver data used for the calculation of the position.

[0072] The receiver may comprise viewing means, in particular a screen, arranged to display the location of the sound event or to depict the location of the sound event on a geographical map.

[0073] Independently or in combination with the above aspects, according to another aspect of the present invention, another object of the present invention is to provide a receiver particularly for implementing the detection and positioning method described above, the receiver comprising:

[0074] - at least one microphone arranged to receive signals representing sound waves emitted during a sound event;

[0075] - Modules selected from the following:

[0076] ■ a noise recognition module configured to recognize a signal representing a sound wave and determine a reception time of the signal by a receiver; or

[0077] ■ a retransmission module configured to transmit a signal representing the sound wave to the remote noise recognition module in an instantaneous or delayed manner;

[0078] - a positioning module storing the position of the receiver or a geolocation module configured to provide the position of the receiver at the time of reception of the signal;

[0079] The receiver is configured to:

[0080] i) sending data called "receiver data", said receiver data comprising a sound signal or a reception time of a sound signal received by a receiver, and a position of said receiver at the reception time;

[0081] ii) receiving receiver data associated with other receivers and for calculating the position of the sound event based on the received receiver data and its own receiver data.

[0082] computer program

[0083] In combination with the above aspect, according to another aspect of the present invention, another object of the present invention is to provide a computer program product, wherein the computer program product comprises a code stored on a physical medium or downloadable from a server, wherein the code comprises code instructions intended to be executed on a computer device such as a server, a computer or a mobile phone, wherein these instructions, when executed, result in the implementation of the detection and positioning method described above, in particular:

[0084] - retrieving data associated with each receiver, called "receiver data", said data containing the reception time of the sound signal or of the receiver receiving the sound signal, and the position of said receiver at that reception time;

[0085] -optionally, calculating the reception time of the sound signal;

[0086] - for at least two pairs of receivers, calculating a difference in distance between the sound event and each receiver in each pair of receivers based on a reception time of the sound signal received by the receiver;

[0087] - determining the location of the sound event by trilateration based on the calculated difference in distances and the location of the receiver at the corresponding reception time; and

[0088] - Optionally, display the location of the sound event on a screen such as a computer, phone, or augmented reality headset;

[0089] -Optionally calculate the date of the sound event.

[0090] Storage media

[0091] In combination with the above aspects, according to another aspect of the present invention, a further object of the present invention is to provide a computer-readable storage medium storing a computer program, wherein the computer program includes program code instructions for executing the detection and positioning method described above.

[0092] Computer Server

[0093] In combination with the above aspects, according to another aspect of the present invention, a further object of the present invention is to provide a computer server for implementing the detection and positioning method described above, wherein the computer server is configured to:

[0094] - receiving data called "receiver data", said receiver data comprising a sound signal or a time of reception of a sound signal by a receiver, and the position of said receiver at that reception time;

[0095] - calculating, for each receiver, the date of the time of reception of the sound event, if not already calculated, and then calculating, for at least two pairs of receivers, the difference in distance between the sound event and each of the two receivers in each pair; and

[0096] - Determine the position of the sound event based on the calculated distance, in particular by trilateration.

[0097] Trilateration calculation

[0098] If a sound event occurs in a plane formed by three receivers, for example, if the sound event and the three receivers are all on the ground, then the sound event is located at the intersection of two hyperbolas, the receiver of the sound event is the focus, and the difference in distance to the focus is the difference in reception time of the sound from the event at the receiver multiplied by the speed of sound.

[0099] If the sound event is not in the plane of the three receivers, it is preferable to place a fourth receiver outside the plane formed by the first three receivers. This fourth receiver could be on a drone, a pole, or even atop a building. The location of the sound event is the intersection of the three hyperboloids, with the three receivers being the focal points. The difference in distance from the location of the sound event to the focal points is the difference in reception time for the sound from the event at each receiver multiplied by the speed of sound.

[0100] For example, the position can be calculated using an orthogonal x, y, z reference system, where the focus of the first hyperbola is to the right of the x-axis and the focus of the second hyperbola is in the xy plane. The point M(x, y, z) of the first of these two hyperboloids is then verified as:

[0101] x 2 / a 2 –(y 2 +z 2 ) / b 2 =1

[0102] The parameter t can be used so that t = x / ay / b

[0103] So: t*(x / a+y / b)=1+z 2 / b 2 , so x / a+y / b=(1+z 2 / b 2 ) / t

[0104] Then

[0105] x / a=1 / 2[(1+z 2 / b 2 ) / t+t]

[0106] y / b=1 / 2[(1+z 2 / b 2 ) / tt]

[0107] The second hyperboloid is the result of rotating another hyperboloid about the x-axis about an axis parallel to the z-axis and perpendicular to the xy-plane, resulting in an equation of the form:

[0108] αx 2 +βy 2 +γxy+εz 2 =1

[0109] This equation allows finding one or more values ​​of t for each z:

[0110] α(a*1 / 2(t+(1+z 2 / b 2 ) / t)) 2+β*(b1 / 2(-t+(1+z 2 / b 2 ) / t)) 2 +γab*(t 2 -(1+z 2 / b 2 )2 / t 2 ) / 4+εz 2 =1

[0111] α(a*1 / 2(t 2 +(1+z 2 / b 2 )) 2 +β*(b1 / 2(-t 2 +(1+z 2 / b 2 ))) 2 +γab*(t 4 -(1+z 2 / b 2 )) / 4+εz 2 t 2 =t 2

[0112] In other words:

[0113] α(a*1 / 2(t 4 +(1+z 2 / b 2 ) 2 +2*(1+z 2 / b 2 )*t 2 )+β*b1 / 2*(t 4 +(1+z 2 / b 2 ) 2 -2*(1+z 2 / b 2 )*t 2 )+γab*(t 4 -(1+z 2 / b 2 )) / 4+εz 2 t 2 =t 2

[0114] In other words: t 4 *(αa / 2+β*b / 2+γab / 4)+t 2 *(αa(1+z 2 / b 2 )-βb(1+z 2 / b 2 )+εz 2-1)+αa / 2*(1+z 2 / b 2 ) 2 +β*b / 2*(1+z 2 / b 2 )2-γab / 4*(1+z 2 / b 2 )=0

[0115] This is to allow t 2 As a function of z, then x and y are expressed as functions of z, and for t 2 For example, an equation can have at most two solutions.

[0116] The third hyperboloid is a quadratic equation in x, y, and z, which is then converted into four equations in t. The Cartesian equation of the third hyperboloid can thus generate four equations in t, one or more of which are solved using numerical techniques, particularly the method of bisection.

[0117] The possibility of finding eight different values ​​for a single value of z reflects the fact that the quadratic equation of each hyperbola does not take into account the sign of the difference in distance from the focus. Verifying each solution by taking into account the sign of the difference d1-d2 between the distances from the emitter makes it possible to find a unique intersection point for the three hyperboloids. BRIEF DESCRIPTION OF THE DRAWINGS

[0118] The present invention will be better understood from the following detailed description of non-limiting embodiments of the invention, with reference to the accompanying drawings, in which:

[0119] Figure 1 Schematic diagram illustrating an example of a system according to the present invention;

[0120] Figure 2 A method for locating a sound event according to the present invention is illustrated;

[0121] Figure 3 Illustrated examples of 2D trilateration calculations; and

[0122] Figure 4 Another example of a system according to the invention is schematically illustrated. DETAILED DESCRIPTION

[0123] In the rest of the specification, the same reference numerals are used for the same elements or the same functions. For the sake of brevity of this description, not every figure is described with reference to it, and only the differences between the embodiments are described.

[0124] For the sake of clarity, the figures are not always drawn to scale.

[0125] Positioning system

[0126] Figure 1 An embodiment of a system 1 for detecting and localizing sound events in a space E according to the invention is illustrated.

[0127] Space E is open.

[0128] The system 1 comprises three mobile receivers 2: 2a, 2b and 2c and one fixed receiver 3, each of which is equipped with a microphone 4. Each of them is designed to receive at least one signal representative of the sound waves emitted during a sound event S (called "sound signal").

[0129] Two of the mobile receivers 2 are mobile telephones 2a and 2c of the "smartphone" type comprising a dedicated application for locating sound events. The phones 2a and 2c are carried by two operators, for example.

[0130] The telephones 2a and 2c also comprise a digital screen 6 for displaying information.

[0131] The telephones 2a and 2c comprise a noise recognition module configured to recognize sound signals and determine the reception time of said signals by the receiver, for example the OSSR “Orelia Sound Source Recognition” software sold by the company Orelia and described in application FR 2 923 043.

[0132] The other portable receiver 2b is a device present in a car, for example, a vehicle control panel provided with a microphone.

[0133] The three mobile receivers 2 contain a geo-positioning module configured to provide their own position, in this case a GNSS satellite navigation system.

[0134] The fixed receiver 3 is arranged at a height located at the top of the tower 8. The position of the microphone 4 of the attached receiver 3 is known and the fixed receiver 3 does not have a geolocation system. Alternatively, the fixed receiver 3 also contains a geolocation module.

[0135] The system 1 further comprises a first processing device, which is a server 10 in this example.

[0136] As described below, the server 10 includes a storage medium containing a computer program and is configured to:

[0137] - receiving data associated with each receiver 2a, 2b, 2c, 3, called "receiver data", said receiver data comprising the sound signal or the time of reception of the sound signal by the receiver 2a, 2b, 2c, 3 and the position of the receiver at that reception time;

[0138] - for at least three pairs of receivers each comprising two of the four receivers 2a, 2b, 2c, 3, calculating a distance difference between the event and each receiver in each pair of two receivers, wherein the distance is calculated based on the reception time of the sound signal at each receiver and the speed of sound propagation;

[0139] - Based on the calculated distance differences and the positions of the receivers 2a, 2b, 2c, 3, the position of the sound event is determined by trilateration.

[0140] As shown, the server 10 comprises a screen 11 which allows in particular to display the position of the determined sound event. This screen is also used to browse the sound event log in order to display its position and time.

[0141] For example, the system 1 includes an augmented reality headset 12 connected to a server 10 via a wireless link for displaying the determined location of the sound event.

[0142] For example, the headset 12 may be worn by an operator in the field to quickly locate a sound event.

[0143] The server 10 comprises, for example, a communication device 13 for exchanging information with the various receivers 2 , 3 and with the headset 12 .

[0144] In this example, three portable receivers 2 and a fixed receiver 3 are configured to transmit receiver data to a server 10 .

[0145] For example, data transmission is performed wirelessly to the server 10 via telephone or 3G, 4G or 5G electromagnetic communications, while Wi-Fi transmission mode allows devices to communicate over a mesh network in the event of a failure of the 3G, 4G and 5G telephone networks.

[0146] Furthermore, the phone 2a in this case is configured to receive receiver data 2b associated with the car, the phone 2c and the fixed receiver 3 and to calculate the position of the sound event S based on the data received from said receivers and its own receiver data.

[0147] For example, the phone 2a is configured to store the position of the sound event S once it is calculated in a storage unit of the receiver (e.g., an SD card), wherein the calculated position of the sound event S is preferably stored together with information related to the calculated receiver data for that position.

[0148] For example, the portable receiver 2 and the server 10 include computers with synchronized clocks for determining the reception time of the sound signal. The date of the reception time of the sound signal of the fixed receiver 3 is the date calculated by the server 10 or the telephone 2a.

[0149] The portable receiver 2 and the fixed receiver 3 are advantageously configured to electronically sign the receiver data in order to allow the location of the sound event to be verified.

[0150] Positioning method

[0151] Figure 2 An example of a method according to the invention for locating a sound event S using the system 1 described above is illustrated.

[0152] The sound event S may correspond, for example, to a gunshot or the impact of such a shot, an explosion, an accident, a lightning strike, an alarm or any other sound event that generates a sound signal.

[0153] In a first step, the portable receiver 2 and the additional receiver 3 will detect a sound signal representing a sound event S.

[0154] The time of reception of the sound signal is determined directly by the computer of the portable receiver 2. Each portable receiver 2 then sends to the server 10 its position at the time of reception and the time of reception of the sound signal.

[0155] The stationary receiver 3 , for its part, continuously sends its sound signal to the server 10 . Therefore, the reception time of the sound signal by the stationary receiver 3 is determined by the computer of the server 10 . The location of the stationary receiver 3 is also known to the server 10 .

[0156] For example, telephones 2a and 2c are located at a height Z1.

[0157] The vehicle 2b is located at a height Z2 which is slightly higher than the height Z1.

[0158] The receiver 3 is located at a height Z3 which is much higher than the height Z2, for example 3 times or 10 times higher.

[0159] The sound event S is located at height Zs.

[0160] Next, the server 10 calculates the distance difference between the sound event S and each receiver in each pair of receivers based on the reception date of the sound signal received by the receiver, for at least three pairs of receivers 2 or 3, preferably for at least four pairs of receivers, i.e., for example, the telephone 2a / car 2b pair, the telephone 2a / fixed receiver 3 pair, the telephone 2a / phone 2c pair, and the car 2b / fixed receiver 3 pair.

[0161] These distance differences are calculated, for example, by multiplying the speed of sound by the difference between the reception times of each pair of receivers.

[0162] Next, the position of the sound event S is determined by trilateration based on the calculated distance difference and the position of the receiver at the corresponding reception time.

[0163] As mentioned above, the location of the sound event S can also be determined by the telephone 2a.

[0164] Once the position of the sound event S has been determined, the location information L is displayed on the screen 11 of the server 10 and the location is depicted on the mask of the headset 12 and on the screen 6 of the phone 2a.

[0165] This set of data, ie the location of the sound event S and the receiver data, may then be stored in the internal memory of the server 10 and the phone 2a.

[0166] During the reception of the sound signal, the portable receiver 2 may be stationary or mobile.

[0167] For example, a car carrying device 2b can move during the reception of the sound signal. In this case, the car transmits its speed and direction together with the receiver data to take into account the Doppler effect when identifying noise.

[0168] It may be worthwhile to adjust the accuracy involved in determining the geographical location by taking into account the meteorological or microclimate conditions in the vicinity of the receivers 2, 3, where temperature and air pressure significantly influence the speed of sound.

[0169] The optimization can also be performed using an iterative method until convergence is achieved, taking into account the meteorological conditions around the receivers 2 and 3 and in the vicinity of the position iteration calculated for the event S. In particular, such convergence can be achieved until the difference in distance obtained between two consecutive iterations is less than a desired tolerance, for example less than 10 cm, or even less than 5 cm.

[0170] The phone 2c receiving the geographic location of the sound event can broadcast an audible or visual warning indicating the danger while indicating the location of the event on a map or 3D depiction of the environment.

[0171] Lasers and / or searchlights arranged on the vehicle carrying the device 2b can be controlled to direct their beams towards the sound event S. Similarly, a camera, preferably equipped with a telephoto lens, arranged on the vehicle, for example, can be controlled to photograph the location where the sound event occurs.

[0172] Examples of trilateration calculations are Figure 3 As shown in the diagram.

[0173] In this example, the calculations are performed in two dimensions, using three receivers 2a, 2b and 2c, and the system then makes it possible to localize an event S occurring in the plane in which the three receivers are located.

[0174] Alternatively, all mobile receivers 2 are located on drones that preferably fly at different altitudes, such as 15m, 20m, 25m, 26m and 100m.

[0175] The sound event S occurs in a plane formed by the three receivers 2a, 2b and 2c, the positions of which at the time of reception of the sound signal are known, in particular by means of a geolocation module.

[0176] To determine the location of event S, two hyperbolas are determined.

[0177] The first hyperbola H1 is determined using receivers 2a and 2c as foci and based on the distance difference from event S to these two foci, which is the difference between the dates on which the receivers received the sound from event S multiplied by the speed of sound.

[0178] The second hyperbola H2 is determined using receivers 2a and 2b as foci, based on the distance difference from event S to these two foci (the distance difference is the difference between the dates on which the receivers receive the sound from event S multiplied by the speed of sound), and based on the distance D2 between receivers 2a and 2b.

[0179] Then, the sound event S is located at the intersection It of these two hyperbolas H1 and H2.

[0180] To refine the positioning, receivers 2b and 2c can be used as foci, and a third hyperbola H3 can be determined based on the distance difference from event S to these two foci (the distance difference is the difference between the dates on which the receivers receive the sound from event S multiplied by the speed of sound) and based on the distance D3 between receivers 2b and 2c.

[0181] For three-dimensional determination, the calculations are similar, using a hyperbolic surface and additional receivers.

[0182] Other positioning systems

[0183] Figure 4 Another example of a system 1 according to the invention is shown, which system comprises five mobile receivers 2 and one fixed receiver 3 .

[0184] and Figure 1 Compared to the system 1, the second system 1 further includes a flying drone 2d and a third mobile phone 2e.

[0185] Phone 2e operates similarly to phones 2a and 2c, eg, it is a different model.

[0186] For example, the drone 2d is remotely controlled by an operator or software having a remote controller 7. The drone 2d includes a transmitting module configured to transmit a sound signal to a noise recognition module present in the remote controller 7 in an instantaneous or delayed manner.

[0187] The noise recognition module of the remote control 7 of the drone 2 d is configured to recognize sound signals and determine the time of reception of said signals by the receiver, for example the OSSR “Orelia Sound Source Recognition” software sold by the company Orelia and described in application FR 2 923 043.

[0188] The drone 2d can be configured to fly at a given distance, for example, at a given altitude (e.g., 100 m) directly above a remote point that is a given distance (e.g., 200 m) from a straight line passing through the fixed receiver 3 and one of the mobile phones 2a and 2c. Alternatively, the drone 2d is preferably controlled to maintain proximity to the center of gravity of the transmitters 2a, 2c, 2e, and 3 located on the ground.

[0189] In order to locate the sound event S using the second system, the positioning method used is similar to the previous positioning method, except that more receivers 2 and 3 are used, which can improve the positioning accuracy of the sound event S.

[0190] The telephones 2a, 2c and 2e are located at the same height Z1.

[0191] The vehicle 2b is located at a height Z2 which is slightly higher than the height Z1.

[0192] The receiver 3 is located at a height Z3 that is higher than the height Z2, for example, 3 times higher.

[0193] The drone 2d is flying at an altitude Z4 higher than the altitude Z3, for example, an altitude of 100 m.

[0194] The present invention is not limited to the above-mentioned examples.

[0195] In particular, the number of portable receivers 2 may vary, for example it may be between two and ten.

[0196] When the system comprises a large number of receivers 2 and 3, for example at least 4, in particular at least 6, the method may comprise the step of selecting receivers 2 and 3 from the group of receivers that receive the sound signal.

[0197] For example, for each receiver quadruple, the receiver defining the largest space is determined by calculating the volume defined by each quadruple, and then the reception time of the sound signal received by the receiver quadruple is used to determine the first geographical location of the noise.

[0198] During the second phase, if the first localization of the noise is successful, the fifth receiver closest to the sound event can be used to refine the position, and then one more receiver can be used until the position is sufficiently accurate or no longer improves. In the event of failure, that is, if no intersection can be found, for example, if the sound signal received by the receiver is caused by noise reflected from a wall, another smaller quadruple can be used.

[0199] The system 1 may be without the additional receiver 3 .

[0200] The system can be operated without a portable receiver.

[0201] The system may comprise at least two portable receivers.

Claims

1. A method for locating a sound event (S) by measuring the reception times of signals representing sound waves emitted during a sound event (S) by at least three receivers (2, 3), wherein the positions of the receivers (2, 3) are known or the receivers (2 and 3) are equipped with geolocation modules configured to provide the positions of the receivers (2, 3), the method comprising the following steps: a) determining for each receiver (2, 3) the time of reception of a signal, referred to as a "sound signal", representing the sound waves emitted during the sound event (S); b) calculating, for at least two pairs of receivers (2, 3), a difference in distance between the receivers (2, 3) in each pair and the sound event (S) based on the reception time of the sound signal; c) determining the position of the sound event (S) by trilateration based on the difference of one or more calculated distances and the position of the receivers (2, 3) at the corresponding reception times.

2. A positioning method according to claim 1, wherein at least one receiver (2, 3), preferably all receivers (2, 3), are selected from a smartphone (2a, 2c, 2e), a drone equipped with a microphone (2d), a headset equipped with a microphone, smart glasses equipped with a microphone, a smart watch equipped with a microphone, a surveillance camera equipped with a microphone, an alarm unit base equipped with a microphone, a home automation unit equipped with a microphone, a connected vibration sensor, a voice assistant, a networked vehicle equipped with a microphone in the passenger compartment (2b) or any device including a microphone (4).

3. A positioning method according to any one of claims 1 and 2, comprising displaying the position of the sound event (S) on a viewing device (6, 11, 12), such as a computer, a telephone (2a, 2c, 2e) or an augmented reality headset (12), such as a screen.

4. Localization method according to any of the preceding claims, comprising broadcasting an action to be performed after step c) of determining the position of the sound event (S).

5. Method according to any of the preceding claims, comprising storing the position of the sound event (S) and the noise perceived by the receiver (2, 3) on a digital storage unit.

6. The method according to claim 5 further comprises storing the reception time of the sound signal by the receiver (2, 3) in the storage unit, in particular together with the position of the receiver (2, 3) at the reception time of the sound signal in the storage unit.

7. The method according to any one of claims 5 to 6 comprises a step involving electronically signing the location of the sound event (S) and / or the data used to calculate the location of the sound event (S), in particular the time of reception of the sound signal and / or the location of the receiver (2, 3) at these reception times.

8. Method according to any one of claims 5 to 7, wherein the storage unit is a server (10) remote from the receiver (2, 3).

9. Method according to any of the preceding claims, wherein the position determination in step c) is performed by one of the receivers (2, 3).

10. Method according to any one of claims 1 to 8, wherein the position determination in step c) is performed by a server (10) remote from the receiver (2, 3).

11. Method according to any of the preceding claims, wherein step a) is performed by a remote server (10) for at least one of the receivers (2, 3), the sound signal being retransmitted by the receiver (2, 3) to said server (10).

12. Method according to any of the preceding claims, wherein step b) is performed by a remote server (10) for at least one of the receivers (2, 3), the reception time being resent by the receiver (2, 3) to said server (10).

13. Method according to any one of claims 1 to 10, wherein step a) and / or step b) is performed by at least one of the receivers (2, 3).

14. Method according to any of the preceding claims, wherein at least 4 receivers (2, 3), preferably at least 6 receivers (2, 3) are used, the method comprising the step of selecting a receiver (2, 3) from among the receivers (2, 3) receiving the sound signal.

15. A system (1) for detecting and localizing a sound event (S), comprising: - at least three receivers (2, 3), each receiver being arranged to receive at least one signal, called "sound signal", representative of the sound waves emitted during the sound event (S); Each receiver (2, 3) is equipped with at least one microphone (4) and comprises: o a positioning module storing the position of the receiver (2, 3) or a geo-positioning module configured to provide the position of the receiver (2, 3); and ○Select from the following modules: ■ a noise recognition module configured to recognize a sound signal and determine a reception time at which the signal is received by a receiver (2, 3); or ■ a retransmission module configured to transmit a signal representing the sound to the remote noise recognition module in an instantaneous or delayed manner; - a processing device configured to: o receiving data associated with each receiver (2, 3), called "receiver data", said receiver data comprising a sound signal or a reception time at which the receiver (2, 3) received the sound signal, and the position of said receiver (2, 3) at that reception time; o calculating the date of the time of reception of the sound event, if that date has not already been calculated, and then calculating, for at least two pairs of receivers (2, 3), the difference in distance between the event (S) and each receiver (2, 3) in each pair of receivers based on the time of reception of the sound signal by the receivers (2, 3); o Based on the calculated difference in distances and the positions of the receivers (2, 3), the position of the sound event (S) is determined by trilateration.

16. The detection and positioning system (1) according to claim 15, wherein at least one receiver (2, 3), preferably all receivers (2, 3) are selected from a smartphone (2a, 2c, 2e), a drone equipped with a microphone (2d), a headset equipped with a microphone, smart glasses equipped with a microphone, a smart watch equipped with a microphone, a surveillance camera equipped with a microphone, an alarm unit base equipped with a microphone, a home automation unit equipped with a microphone, a connected vibration sensor, a voice assistant, a networked vehicle equipped with a microphone in the passenger compartment (2b) or any device including a microphone (4).

17. The system (1) according to any one of claims 15 and 16, comprising one or more fixed receivers (3) arranged at high altitude, in particular on top of a building (8) such as a tower or a pylon, the position of the one or more fixed receivers (3) being known.

18. System (1) according to claim 17, wherein the fixed receiver (3) has no geo-positioning system and its position is known.

19. The system (1) according to claim 15, wherein the computer for determining the time of reception of the sound signal has a synchronized clock or a common clock.

20. A detection and localization system (1) according to any one of claims 15 to 19, the system being configured to use an electronic signature to verify the calculated position of a sound event (S).

21. A detection and positioning system (1) according to any one of claims 15 to 20, wherein the system is configured to store the calculated position of the sound event (S), in particular the verified calculated position, in a storage unit of the system, in particular using a processing device, and / or to send the position to a remote server (10) so that the position is stored in the remote server, the calculated position of the sound event (S) preferably being stored and / or sent together with information related to the receiver data used for the calculation of the position.

22. A detection and localization system (1) according to any one of claims 15 to 21, comprising viewing devices (6, 11, 12) configured to display the location of the sound event (S), these viewing devices (6, 11, 12) in particular comprising an augmented reality headset (12).

23. A receiver (2, 3) for implementing the detection and positioning method according to any one of claims 1 to 14, comprising: - at least one microphone (4) arranged to receive signals representing sound waves emitted during the sound event (S); - Modules selected from the following: ■ a noise recognition module configured to recognize a signal representing a sound wave and to determine a reception time of the signal by a receiver (2, 3); or ■ a retransmission module configured to transmit a signal representing the sound wave to the remote noise recognition module in an instantaneous or delayed manner; - a positioning module storing the position of the receiver (2, 3) or a geolocation module configured to provide the position of the receiver (2, 3) at the time of reception of the signal; Receiver (2,3) is configured to: i) sending data called "receiver data", said data comprising a sound signal or a reception time at which a receiver (2, 3) receives a sound signal, and a position of said receiver (2, 3) at said reception time; ii) receiving receiver data associated with other receivers (2, 3) and for calculating the position of the sound event (S) based on the received receiver data and the receiver's (2, 3) own data.

24. The receiver (2, 3) according to claim 23 is configured to store the calculated position of the sound event (S), in particular the verified calculated position, in a storage unit of the receiver (2, 3) and / or to send the position to a remote server (10) for storing the position in the remote server, the calculated position of the sound event (S) preferably being stored and / or sent together with information related to the receiver data used for the calculation of the position.

25. Receiver (2) according to any one of claims 23 and 24, comprising viewing means (6, 12), in particular a screen (6), arranged to display the location of the sound event (S) or to depict the location of the sound event (S) on a geographical map.

26. A computer program product comprising a code stored on a physical medium or downloadable from a server, comprising code instructions intended to be executed on a computer device such as a server (10), a computer or a mobile phone (2a, 2c, 2e), wherein these instructions, when executed, cause the implementation of the detection and positioning method according to any one of claims 1 to 14, and comprising the steps of: - retrieving data associated with each receiver, called "receiver data", said data comprising the sound signal or the time of reception of the sound signal by the receiver (2, 3), and the position of said receiver (2, 3) at that reception time; -optionally, calculating the reception time of the sound signal; - for at least two pairs of receivers (2, 3), calculating the difference in distance between the sound event (S) and each receiver (2, 3) in each pair of receivers based on the reception time of the sound signal received by the receivers (2, 3); - determining the position of the sound event (S) by trilateration based on the calculated differences in the distances and the positions of the receivers (2, 3) at the corresponding reception times; and - Optionally, displaying the location of the sound event (S) on a screen (6, 11, 12) of, for example, a computer, a phone (2a, 2c, 2e) or an augmented reality headset (12).

27. A computer-readable storage medium storing a computer program, comprising program code instructions for executing the detection and positioning method according to any one of claims 1 to 14.

28. A computer server (10) for implementing the detection and positioning method according to any one of claims 1 to 14, the computer server being configured to: - receiving from each receiver data referred to as "receiver data", said data comprising a sound signal or the time of reception of the sound signal by the receiver (2, 3), and the position of said receiver (2, 3) at that reception time; - calculating, for each receiver, the date of the time of reception of the sound event (S), if this date has not already been calculated, and then calculating, for at least two pairs of receivers (2, 3), the difference in distance between the sound event (S) and each of the two receivers in each pair (2, 3); as well as - Determine the location of the sound event (S) by trilateration based on the calculated distance.

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