WO2024256540A1 - Aerial drone comprising a system for transceiving electromagnetic communication signals, and associated locating method - Google Patents

Abstract

The present invention relates to an aerial drone (25) comprising a system (35) for transceiving electromagnetic communication signals. The transceiving system (35) comprises a block (40E) for transmitting electromagnetic signals and a block for receiving electromagnetic signals. Each of the transmit block and the receive block comprises an antenna and a reflector of electromagnetic signals which is oriented toward the respective antenna.

Description

DESCRIPTION

Drone aircraft comprising a system for transmitting and receiving electromagnetic communication signals and associated localization method

The present invention relates to an aircraft drone comprising a system for transmitting and receiving electromagnetic communication signals.

The present invention also relates to a method for locating a mobile terminal from such an aircraft drone.

The present invention relates to the field of mobile terminal location devices, such as mobile phones. In particular, the invention focuses on determining a location of a mobile terminal by a third-party system that is not the mobile terminal itself.

When it is desired to locate a mobile terminal, it is known to use communications interception systems and to trace the location of the terminal from the intercepted communications of said terminal.

However, since these terminals are usually owned by individuals, they are positioned close to ground level, close to individuals.

However, individuals evolve in environments comprising obstacles on which electromagnetic signals are reflected and attenuated with each reflection. Thus, to be able to intercept these signals, it is required that the interception system be located sufficiently close to the mobile terminal, i.e. around a hundred meters from the latter. To achieve such proximity, it is generally required that a group of individuals carrying the interception system be deployed and approach sufficiently close to the mobile terminal.

This deployment induces several problems.

First, the use of human intervention on site creates a risk for individuals who must necessarily expose themselves.

Second, the high proximity required for the interception system significantly reduces the stealth of the interception. In a surveillance context, for example in anticipation of a police intervention, there is a risk that this lack of stealth could jeopardize the future intervention.

There is therefore a need for a solution that can locate a mobile terminal while remaining stealthy and without exposing individuals. For this purpose, the present invention relates to an aircraft drone comprising a system for transmitting and receiving electromagnetic communication signals, the transmitting and receiving system comprising an electromagnetic signal transmitting block and an electromagnetic signal receiving block, each of the transmitting block and the receiving block comprising an antenna and an electromagnetic signal reflector oriented in the direction of the respective antenna.

In this application, the term “drone” means any device capable of being piloted autonomously or remotely, without a human user needing to be on board the device.

Thanks to the use of an aircraft drone, detection is effective. Indeed, by gaining height in relation to the mobile terminal, a link assessment between the aircraft drone and the mobile terminal is of better quality. Thus, it is possible to exchange with the mobile terminal from a further distance.

In addition, the presence of reflector(s) in addition to the antennas makes it possible to maximize the transmission and reception capacity of the antennas by performing a function of concentrating the antenna lobe, thus maximizing the gain of the antennas.

According to particular embodiments, the aircraft drone comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

- each antenna and each reflector are substantially flat,

- each antenna has a lower face and an upper face, the upper face of the transmitting antenna being the face for transmitting electromagnetic signals, the upper face of the receiving antenna being the face for receiving electromagnetic signals, each reflector being placed substantially above the respective antenna when the aircraft drone is on the ground, the aircraft drone defines a fuselage, the transmitting block and the receiving block being placed protruding from the fuselage of the aircraft drone, the aircraft drone is a fixed-wing drone comprising a nose, the transmitting and receiving blocks being arranged on either side of the nose of the aircraft drone, each of the transmitting block and the receiving block further comprises a support for the antenna and the reflector,

- each support defines: o a base matching the shape of the fuselage of the aircraft drone, and o two portions facing each other and projecting from the fuselage of the aircraft drone, respectively supporting the antenna and the reflector,

- each portion has, in section, a curved geometry defining a maximum thickness and a longitudinal dimension, the maximum thickness being located approximately halfway along the longitudinal dimension, and

- the aircraft drone has a mass less than or equal to 25 kilograms.

The present invention also relates to a method for locating a mobile terminal, called a mobile terminal of interest, in an environment, from such an aircraft drone, the environment comprising a relay station and at least one mobile terminal of interest, the mobile terminal of interest being capable of exchanging data with the relay station, the method comprising: the aircraft drone flying over the environment, the aircraft drone flying at a height preferably between 750 and 1500 meters, the identification of the relay station by the aircraft drone, the transmission, by the transmission block of the aircraft drone, of an identification request to any mobile terminals present in the environment, the identification request comprising an identifier of the identified relay station,

- the reception, by the reception block of the aircraft drone and from each possible mobile terminal, of a respective identifier of the mobile terminal, the identification of the mobile terminal of interest from the identifiers of mobile terminals received, the calculation of a link budget between the aircraft drone and the mobile terminal of interest, and the determination of the location of the mobile terminal of interest from the calculated link budget.

The invention will appear more clearly on reading the description which follows, given solely as a non-limiting example, and made with reference to the appended drawings in which:

[Fig. 1] Figure 1 is a diagram of an environment in which the aircraft drone according to the invention is deployed,

[Fig. 2] Figure 2 is a diagram of the aircraft drone according to the invention,

[Fig. 3] Figure 3 is a diagram of an electromagnetic signal transmission-reception system included in the aircraft drone according to the invention,

[Fig. 4] Figure 4 a detailed view of an area of the aircraft drone, and

[FIG. 5] Figure 5 is a flowchart of a localization method according to the invention. In this application, the terms “lower” and “upper” mean notions of low and high which are defined in relation to an axis substantially vertical to a ground.

Figure 1 represents a 10 environment.

The environment 10 is for example an area including one or more villages 12 connected by roads 14.

In the example of Figure 1, the environment 10 includes three villages 12.

The environment 10 comprises at least one relay station 15 and at least one mobile terminal of interest 20 represented by a triangle in FIG. 1.

In the example of Figure 1, the environment 10 comprises five relay stations 15.

Optionally, the environment 10 further comprises other mobile terminals 22, represented by crosses in FIG. 1.

Each relay station 15 is for example a 2G, 3G, 4G, 5G or later technology antenna, capable of exchanging with each mobile terminal 20, 22 within a proximity radius, electromagnetic signals for telephone or digital communication. The frequency of said electromagnetic signals is between 650 Mega Hertz and 3 Giga Hertz.

The mobile terminal of interest 20 and optionally each other mobile terminal 22 is for example a mobile telephone capable of exchanging, with a relay station within a proximity radius, electromagnetic signals in the aforementioned frequency bands.

The environment 10 is flown over by an aircraft drone 25, also called drone 25, represented by a square in FIG. 1. Preferably, the aircraft drone 25 flies at a height of between 750 and 1500 meters. The height of the aircraft drone 25 is for example measured relative to the altitude difference between the aircraft drone 25 and the altitude of the environment 10, relative to sea level.

As will be explained in detail below, the aircraft drone 25 is capable of exchanging electromagnetic signals with the mobile terminals 20, 22, thus emulating the operation of a relay station 15.

The aircraft drone 25 is shown in FIG. 2. The aircraft drone 25 is for example a fixed-wing aircraft having substantially the shape of an airplane. The drone 25 extends, in a longitudinal direction L, between a tail 31 and a nose 32. When the drone 25 flies, it moves in the air substantially in the longitudinal direction L, its nose 32 facing forward.

The wing of the drone 25, i.e. its wings, preferably extends in a transverse direction T, perpendicular to the longitudinal direction L when the drone 25 is on the ground. A vertical direction V is defined as perpendicular to the longitudinal L and transverse T directions. The vertical direction V is substantially perpendicular to the ground when the drone 25 is on the ground.

The aircraft drone 25 for example has a mass of less than 25 kilograms. We then speak of a mini-drone.

The aircraft drone 25 preferably comprises a fuselage 33 covering it. The fuselage 33 is for example made of carbon or of a material impermeable to electromagnetic signals in the frequency band between 600 MHz and 3 GHz.

The drone 25 includes a system for transmitting and receiving electromagnetic communication signals 35, also called system 35.

Referring to FIG. 3, the system 35 comprises a block 40E for transmitting electromagnetic signals, a block 40R for receiving electromagnetic signals, and optionally a processing unit 50.

The transmission blocks 40E and reception blocks 40R are preferably arranged on either side of the nose 32 of the aircraft drone 25, as visible in FIG. 2 for the transmission block 40E.

The 40E transmitter block and the 40R receiver block are optionally placed protruding from the fuselage 33 of the drone 25.

Referring to FIG. 3, each of the transmitting block 40E and the receiving block 40R comprises an antenna 55E, 55R and a reflector 60E, 60R of electromagnetic signals oriented towards the respective antenna 55E, 55R.

In particular, the antenna 55E of the transmission block 40E is intended to transmit electromagnetic signals advantageously having a frequency between 650 MHz and 3 GHz.

The 55R antenna of the 40R receiving block is intended to receive electromagnetic signals advantageously having a frequency between 650 MHz and 3 GHz.

Each antenna 55E, 55R is for example a directional antenna comprising a favored direction of transmission or reception.

The 60E, 60R reflectors are preferably identical to each other.

Optionally, each antenna 55E, 55R and each reflector 60E, 60R are substantially planar. This is then referred to as a “patch antenna”. Thus, each antenna 55E, 55R and each reflector 60E, 60R preferably has a substantially rectangular geometry. The dimensions of each antenna 55E, 55R and each reflector 60E, 60R are for example substantially identical. Each 55E, 55R, 60E, 60R is for example a block with a long side of seventeen centimeters, a short side of six centimeters, and a millimeter thick. The long side preferably extends in the longitudinal direction L.

Each antenna 55E, 55R preferably has a lower face 65E and an upper face 70E. The upper face 70E of the transmitting antenna 55E is the face for transmitting the electromagnetic signals. In other words, the electromagnetic signals are substantially emitted by the upper face 70E in a direction substantially perpendicular to said upper face 70E, and in a direction opposite to the lower face 65E.

The upper face 70R of the receiving antenna 55R is the receiving face of electromagnetic signals. In other words, the electromagnetic signals picked up by the receiving antenna 55R are picked up by the upper face 70R of said antenna 55R.

Each reflector 60E, 60R is optionally placed substantially above the respective antenna 55E, 55R when the aircraft drone 25 is on the ground.

It is then understood that during the emission of electromagnetic signals by the emission block 40E, the upper face 70E of the emitting antenna 55E emits said signals towards the reflector 60E. These signals are then reflected on the reflector 60E and directed towards the ground of the environment 10, thus forming an emission cone. The presence of the reflector 60E then makes it possible to increase the level of radiated emission signal compared to a direct emission by the antenna 55E towards the ground.

Similarly, it is understood that when receiving the electromagnetic signals by the receiving block 40R, the electromagnetic signals reach the reflector 60R from the ground of the environment 10. The signals are then reflected on said reflector 60R and reach the receiving antenna 55R where they are picked up. The presence of the reflector 60R then makes it possible to increase the performance of the receiving cone directed towards the ground compared to the performance of the receiving antenna 55R directly directed towards the ground.

Each of the transmission block 40E, and of the reception block 40R preferably further comprises a support 75E, 75R of the antenna 55E, 55R and of the reflector 60E, 60R, as visible in FIG. 3.

Each support 75E, 75R defines a base 85E, 85R matching the shape of the fuselage 33 of the drone 25, and a pair of portions 86E, 86R, 87E, 87R facing each other and projecting relative to the fuselage 33.

The base 85E, 85R defines for example holes 88 for the passage of screws not shown, to fix the support 75E, 75R on the fuselage 33. As a variant, each base 85E, 85R is glued to the fuselage 33. Each portion 86E, 86R, 87E, 87R respectively supports the antenna 55E, 55R and the reflector 60E, 60R. In other words, for the transmitting block 40E, a first portion 86E supports the transmitting antenna 55E, and a second portion 87E supports the associated reflector 60E. Similarly, for the receiving block 40R, a first portion 86R supports the receiving antenna 55R, and a second portion 87R supports the associated reflector 60R.

For example, each portion 86E, 86R, 87E, 87R envelops the antenna 55E, 55R or the associated reflector 60E, 60R.

In the example shown in FIG. 3, each support 75E, 75R is a single piece, i.e. made from a single piece. Alternatively, for each support 75E, 75R, the portions 86E, 86R, 87E, 87R and the base 85E, 85R are made from several pieces, for example assembled with glue.

Each 75E, 75R support is for example made by additive manufacturing of plastic material. The plastic material is advantageously transparent to electromagnetic signals included in the 650 MHz - 3 GHz frequency band.

For each support 75E, 75R, the portions 86E, 86R, 87E, 87R preferably extend from the base in the longitudinal L and transverse T directions so that their ends, in the transverse direction T, are substantially aligned.

Each portion 86E, 86R, 87E, 87R is for example an envelope of material defining an empty internal volume opening onto the respective base 85E, 85R by forming a slot 90E, 90R, 92E, 92R through which the antenna 55E, 55R or the reflector 60E, 60R is inserted during assembly of the system 35.

With reference to Figure 4, in section in a plane perpendicular to the transverse direction T, each portion 86E, 86R, 87E, 87R has a geometry extending mainly in the longitudinal direction L and defining a longitudinal dimension DL. The geometry is curved in the vertical direction V when the drone 25 is on the ground. The geometry therefore defines a maximum thickness EM.

The maximum thickness EM is preferably equal to eight millimeters. The longitudinal dimension DL is preferably equal to seventeen centimeters.

The maximum thickness EM is preferentially located approximately halfway along the longitudinal dimension DL.

Thus, when the drone 25 flies, the portions 86E, 86R, 87E, 87R do not have the effect of an airplane wing and induce a negligible lift effect on the aircraft. Furthermore, the geometry of each portion 86E, 86R, 87E, 87R thus makes it possible to limit the drag of the system 35 and therefore to minimize the influence of said system 35 on the aerodynamic properties of the drone 25. The processing unit 50 is connected to the antennas 55E, 55R and preferably located in the nose 32 of the drone 25 at an equal distance from each block 40E, 40R.

The processing unit 50 is for example capable of emitting electrical signals to the transmitting antenna 55E, for the emission of electromagnetic signals dependent on said signals.

The processing unit 50 is further capable of receiving, from the receiving antenna 55R, electrical signals resulting from the reception of electromagnetic signals by said antenna 55R.

As will be described below, the processing unit 50 is further capable of determining a location of the mobile terminal of interest 20.

The processing unit 50 is an electronic circuit designed to manipulate and/or transform data represented by electronic or physical quantities in registers of the processing unit 50 and/or memories into other similar data corresponding to physical data in the memories of registers or other types of display devices, transmission devices or storage devices.

As specific examples, the processing unit 50 is implemented in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array), or an integrated circuit, such as an ASIC (Application Specific Integrated Circuit).

Alternatively, when the actions implemented by the processing unit 50 are performed in the form of one or more software programs, i.e. in the form of a computer program, also called a computer program product, they are also capable of being recorded on a medium, not shown, that is readable by a computer. The computer-readable medium is, for example, a medium capable of storing electronic instructions and of being coupled to a bus of a computer system. For example, the readable medium is an optical disk, a magneto-optical disk, a ROM memory, a RAM memory, any type of non-volatile memory (for example FLASH or NVRAM) or a magnetic card. A computer program comprising software instructions is then stored on the readable medium. The processing unit 50 is then capable of executing these software instructions.

The drone 25 optionally further comprises a system (not shown) for receiving piloting commands by electromagnetic signals. Said system is preferably located substantially in the middle of the drone 25 between the nose 32 and the tail 31 and comprises a stick antenna intended to receive piloting commands from a user of the drone 25 who is at a distance from the drone 25. The pilot command reception system is separate from the transmission-reception system 35.

The operation of the drone 25 will now be presented with reference to FIG. 5 illustrating a flowchart of a method 100 for locating the mobile terminal of interest 20.

The method 100 initially comprises a flyover step 110 during which the drone 25 flies over the environment 10. The drone 25 then flies at a height preferably between 750 and 1500 meters. This height allows the drone 25 not to be visually and aurally detectable by individuals on the ground.

The method 100 then comprises a step 120 of identification of the relay station(s) 15 by the drone 25. During step 120, the drone 25 carries out a characterization of the antenna network composed of the relay stations 15.

For this purpose, the drone 25 sends for example, via its transmission block 40E controlled by the processing unit 50, an initial signal, in the environment 10. This initial signal is captured by the relay station(s) 15 which in return transmit a relay station identifier 15. The drone 25 captures the relay station identifier(s) 15 via its reception block 40R and its processing unit 50.

The method then comprises a step 130 of transmitting, by the transmitting block 40E of the drone 25, an identification request to any mobile terminals 20, 22 present in the environment. The identification request comprises an identifier of the or each relay station 15 identified. The drone 25 then emulates the behavior of the or one of the relay stations 15 and requests the identification of the mobile terminals in its proximity radius. It is understood that the drone 25 then behaves like a clone of the relay station 15.

The identification request is received by each mobile terminal 20, 22. This identification request is identical, for each mobile terminal 20, 22 which receives it, to a classic identification request sent by the relay station 15 nearby.

Thus, in response, each mobile terminal 20, 22 having received the identification request emits, in all directions, a respective identifier of said terminal 20, 22. The identifier is for example an electromagnetic signal carrying a SIM card number (from the English, Subscriber Identification Module) of the mobile terminal 20, 22.

The method 100 then comprises a step 140 of reception, by the reception block 40R of the drone 25 and from each mobile terminal 20, 22, of the respective identifier of the mobile terminal 20, 22.

Each mobile identifier is for example transmitted, from the reception block 40R, to the processing unit 50 for analysis. The method 100 comprises a step 150 of identifying the mobile terminal of interest 22 from the identifiers of mobile terminals 20, 22 received.

For example, the identification of the mobile terminal of interest 22 is carried out by comparing the identifiers received to a table of identifiers in which the identifier of the terminal of interest 22 is recorded.

The method further comprises a step 160 of calculating a link budget between the drone 25 and the mobile terminal of interest 20. The calculation of the link budget, also called signal-to-noise ratio of the signals received, corresponds for example to the calculation of the signal-to-noise ratio in the electromagnetic signals received comprising the identifier of the terminal of interest 20.

où : ( est le rapport sur bruit des signaux reçus, This quantity is for example calculated according to the following formula: [MATH 1 ]

where: ( is the noise ratio of the received signals,

PIRE is the Equivalent Isotropic Radiated Power of the mobile terminal of interest 20, k is the Boltzman constant, is a parameter characterizing the gain of the reception block 40R, and

D contains all the losses between the mobile terminal of interest 20 and the drone 25.

terminal d’intérêt 20. Ainsi, le rapport signal sur bruit dépend directement de la distance entre le drone 25 et le terminal d’intérêt 20. In this equation, the following quantities are known and/or constant: PIRE, In addition, the quantity D depends directly on the distance between the drone 25 and the

terminal of interest 20. Thus, the signal-to-noise ratio depends directly on the distance between the drone 25 and the terminal of interest 20.

The method 100 finally comprises a step 170 determining the location of the mobile terminal of interest 20 from the calculated link budget.

As indicated previously, the link budget depends directly on the distance between the drone 25 and the terminal of interest 20. Thus, by calculating the link budget it is possible to triangulate the position of the terminal of interest 20. For example, during the determination step 170, the processing unit performs such triangulation.

At the end of the method 100 according to the invention, the mobile terminal of interest 20 is located.

With the drone 25 and the localization method 100 according to the invention, it is possible to locate the mobile terminal of interest 20 quickly, stealthily and without having to expose individuals.

The embodiments and examples previously described can be combined with each other in all technically possible combinations.

Claims

1. Aircraft drone (25) comprising a system (35) for transmitting and receiving electromagnetic communication signals, the transmitting and receiving system (35) comprising a block (40E) for transmitting electromagnetic signals and a block (40R) for receiving electromagnetic signals, each of the transmitting block (40E) and the receiving block (40R) comprising an antenna (55E, 55R) and a reflector (60E, 60R) of electromagnetic signals oriented in the direction of the respective antenna (55E, 55R). 2. Aircraft drone (25) according to claim 1, in which each antenna (55E, 55R) and each reflector (60E, 60R) are substantially planar. 3. Aircraft drone (25) according to claim 1 or 2, wherein each antenna (55E, 55R) has a lower face (65E, 65R) and an upper face (70E, 70R), the upper face (70E) of the transmitting antenna (55E) being the face for transmitting electromagnetic signals, the upper face (70R) of the receiving antenna (55R) being the face for receiving electromagnetic signals, each reflector (60E, 60R) being placed substantially above the respective antenna (55E, 55R) when the aircraft drone (25) is on the ground. 4. Aircraft drone (25) according to any one of the preceding claims, in which the aircraft drone (25) defines a fuselage (33), the transmission block (40E) and the reception block (40R) being placed projecting from the fuselage (33) of the aircraft drone (25). 5. Aircraft drone (25) according to any one of the preceding claims, in which the aircraft drone (25) is a fixed-wing drone comprising a nose (32), the transmission (40E) and reception (40R) blocks being arranged on either side of the nose (32) of the aircraft drone (25). 6. Aircraft drone (25) according to any one of the preceding claims, wherein each of the transmitting block (40E) and the receiving block (40R) further comprises a support (75E, 75R) of the antenna (55E, 55R) and the reflector (60E, 7. Aircraft drone (25) according to claims 2, 4 and 6, in which each support (75E, 75R) defines: - a base (85E, 85R) matching the shape of the fuselage (33) of the aircraft drone (25), and - two portions (86E, 87E, 86R, 87R) facing each other and projecting relative to the fuselage (33) of the aircraft drone (25), respectively supporting the antenna (55E, 55R) and the reflector (60E, 60R). 8. Aircraft drone (25) according to claim 7, in which each portion (86E, 87E, 86R, 87R) has, in section, a curved geometry defining a maximum thickness (EM) and a longitudinal dimension (DL), the maximum thickness (EM) being located substantially at half of the longitudinal dimension (DL). 9. Aircraft drone (25) according to any one of the preceding claims, in which the aircraft drone (25) has a mass less than or equal to 25 kilograms. 10. Method (100) for locating a mobile terminal (20), called a mobile terminal of interest (20), in an environment (10), from an aircraft drone (25) according to any one of the preceding claims, the environment (10) comprising a relay station (15) and at least one mobile terminal of interest (20), the mobile terminal of interest (20) being capable of exchanging data with the relay station (15), the method comprising: the overflight (110) of the environment (10) by the aircraft drone (25), the aircraft drone (25) flying at a height preferably between 750 and 1500 meters, the identification (120) of the relay station (15) by the aircraft drone (25), the transmission (130), by the transmission block (40E) of the aircraft drone (25), of an identification request intended for possible mobile terminals (20, 22) present in the environment (10), the identification request comprising an identifier of the relay station (15) identified, - the reception (140), by the reception block (40R) of the aircraft drone (25) and from each possible mobile terminal (20, 22), of a respective identifier of the mobile terminal (20, 22), the identification (150) of the mobile terminal of interest (20) from the identifiers of mobile terminals (20, 22) received, calculating (160) a link budget between the aircraft drone (25) and the mobile terminal of interest (20), and determining (170) the location of the mobile terminal of interest (20) from the calculated link budget.