EP4314866A1

EP4314866A1 - System and method for searching for beacons

Info

Publication number: EP4314866A1
Application number: EP22717227.7A
Authority: EP
Inventors: Nicolas Sornin
Original assignee: Api K
Current assignee: Api K
Priority date: 2021-03-24
Filing date: 2022-03-24
Publication date: 2024-02-07
Also published as: AU2022242797A1; JP2024511197A; CN117377885A; FR3121230A1; FR3121230B1; CA3211231A1; WO2022200739A1; KR20240000499A

Abstract

The invention relates to a system for searching for a target beacon (BC) attached to an object or to a living being to be located comprising said target beacon (BC) emitting a target radio signal in an emission range (P) and a detection device (F) capable of detecting the target radio signal (SC) emitted by the target beacon (BC), and to the method for searching for the corresponding target beacon (BC).

Description

DESCRIPTION

TITLE: System and process for searching for beacons Technical field of the invention

The present invention relates to a method and system for searching for a target tag attached to an object or a living being to be searched.

Prior technique

It is known to produce a system for searching for a target beacon attached to an object or to a living being to be searched for, such as an avalanche victim detection system for example. It is also known to implement the search method executed by said target beacon search system.

Devices capable of locating people buried by an avalanche can be designated by the term "DVA" Detector of Victims of Avaianche.

These provisions are satisfactory in that it becomes possible to locate a person in a natural environment, for example in the mountains and consequently to help him when he is faced with a critical situation such as an avalanche for example.

However, the operating principle of existing beacon search devices is based on the emission or detection of the intensity of an electromagnetic signal, which limits the emission range of the target beacon to be searched to a few tens of meters. and complicates the search for the target beacon resulting in a difficult search process requiring regular practice to be effective. Furthermore, all DVA-type devices emit similar magnetic signals and therefore a DVA-type device cannot be uniquely identified.

The present invention aims to solve all or part of the drawbacks mentioned above.

The technical problem underlying the invention consists in particular in providing a system and a method for searching for a target beacon attached to an object or a living being to be searched for which has a transmission range greater than several tens of meters , which can uniquely identify the target tag to be searched for and which is simple and economical in structure.

General description

To this end, the subject of the present invention is a method for searching for a target beacon attached to an object or a living being to be searched, said search method being executed by a detection device capable of detecting a target radio signal emitted by the target tag, the search method comprising the following steps: Receiving a target radio signal transmitted by the target beacon comprising target beacon identification information when said detection device is within the transmission range of the target beacon;

Determining a target distance value between the detection device and the target beacon based on a calculation of a propagation time of the radio signal between the target beacon and the detection device;

Comparison of the target distance value and a reference target distance value;

If the target distance value is less than the reference target distance value: i. Determination of the value of the reference target distance according to the value of the target distance; ii. Determination of a reference position according to a position of the detection device;

Determination of a location zone of the target beacon relative to the position of the detection device according to the reference position and the reference target distance.

According to one embodiment, a LORA protocol is used. Reception of the target radio signal corresponds to a response from the target beacon to the emission of a request signal by the detection device. The calculation of the distance takes into account time information relating to the transmission of the request signal and the reception of the target radio signal.

According to one embodiment, the request signal includes an identifier of the target beacon.

According to another embodiment, the target radio signal does not include target beacon identification information. The identification of the target beacon is carried out based on the temporal correspondence between the transmission of the request signal and the reception of the target radio signal.

The method of searching for a target beacon may further exhibit one or more of the following characteristics, taken alone or in combination.

According to a characteristic of the method for searching for a target beacon, the detection device is connected to a guidance interface, itself connected to a magnetic compass and to a GPS coordinate receiver. In the method for searching for a target beacon described, the location zone may comprise a circle centered on the reference position and having a radius defined as a function of the reference target distance.

According to one possibility, the determination of the value of the reference target distance as a function of the value of the target distance comprises an assignment of the value of the target distance to the value of the reference target distance.

Determining a reference position based on a position of the sensing device may include assigning the position of the sensing device to the reference position.

The method of searching for a target tag described may further comprise the following steps:

Receiving a location signal comprising location information of the target beacon when the detection device is within the transmission range of the target beacon;

Transmission of a control signal comprising an order to transmit the target radio signal;

The location signal may contain location information as well as target beacon identification information.

The command signal may include a command to operate the target beacon as a transmitter of the target radio signal in addition to the order to transmit the target radio signal from the target beacon.

The location signal can for example contain an identifier of the target beacon such as a MAC address, geolocation coordinates of the target beacon such as GPS coordinates, a precise instant at which the last known GPS coordinates of the target beacon are calculated, among others.

The command signal designates a signal sent by the detection device by which the detection device commands the target beacon to configure itself as a radio frequency transmitter so that the target beacon can transmit the target radio signal.

The method of searching for a target tag may further include the following steps:

If the value of the target distance is less than the value of the reference target distance, controlling the movement of the detection device along a straight line movement trajectory;

If the target distance value is greater than the reference target distance value, command to move the detection device along a trajectory guided on the circle centered on the reference position and having a radius defined as a function of the reference target distance.

The method of searching for a target tag may further include the following step:

Provision of an indication on a user interface regarding the reference position and the location area.

In the disclosed target beacon search method, providing an indication on a user interface regarding the reference position and location area may include displaying a representation of the reference position and/or the location area on a display device.

According to one possibility, the method of searching for a target tag includes the following step:

Reception of an intermediate radio signal emitted by an intermediate beacon comprising information on the location of the target beacon when said detection device is within the transmission range of the intermediate beacon;

The reception of the intermediate radio signal emitted by the intermediate beacon can be done when said detection device is within the transmission range of the intermediate beacon but outside the range of the target beacon.

The method for searching for tags may further comprise the following step:

Initialization of a reference position according to the location information received from the target beacon;

The location information received from the target beacon may designate the last location information sent by the target beacon, for example before the target beacon stops transmitting the target radio signal.

According to one possibility, the steps of receiving an intermediate radio signal emitted by the intermediate beacon and of determining a reference position according to the location information of the target beacon can be repeated several times.

The present invention also relates to a method for searching for a target beacon attached to an object or to a living being to be searched, said search method being executed by the target beacon emitting within an emission range of the target beacon a target radio signal capable of being detected by a detection device, the search method comprising the following steps:

Receiving a command signal from the detection device comprising a command to transmit the target radio signal; Transmission of the target radio signal comprising target beacon identification information BC;

According to a characteristic of the method for searching for a target beacon, the detection device is connected to a guidance interface, itself connected to a magnetic compass and to a GPS coordinate receiver.

According to one possibility, the method of searching for a target beacon described further comprises the steps of:

Selection of an operating mode of the target beacon from the group comprising a first operating mode called normal and a second operating mode called distress;

Emission of a location signal comprising location information of the target beacon.

The selection of an operating mode of the target beacon in the group comprising a first operating mode called normal and a second operating mode called distress can be done:

• based on an operating mode command sent by a user of the target beacon search system.

• by an action of a carrier of the target beacon in a particular situation where he would need help.

The first so-called normal mode of operation designates a mode of operation of the target beacon in which the target beacon emits a location signal comprising information on the location of the target beacon which can be received by the detection device when the detection device is within the transmission range of the target beacon.

The second so-called distress operating mode designates an operating mode of the target beacon in which an intermediate beacon is capable of retransmitting the location signal of the target beacon. This distress mode allows the detection device to receive the location signal from the target beacon without being within the transmission range of the target beacon.

Thus, the target beacon transmits the location signal which may include a distress marker indicating to the intermediate beacon which receives the location signal from the target beacon to retransmit it. This allows the detection device to receive the location signal either directly or through the intermediate beacon which provides a relay between the target beacon and the detection device.

The invention also relates to a system for searching for a target beacon intended to be attached to an object or to a living being to be searched, comprising: the target beacon intended to be attached to an object or to a living being and emitting within an emission range of the target beacon a target radio signal comprising information identifying the target beacon, the target beacon being configured to put in implements the method previously described; a detection device capable of detecting the target radio signal emitted by the target beacon when said detection device is within the transmission range of the target beacon, the detection device comprising a calculation unit implementing the method described above.

The search system for a target beacon may further exhibit one or more of the following characteristics, taken alone or in combination.

According to a characteristic of the system for searching for a target beacon, the detection device is connected to a guidance interface, itself connected to a magnetic compass and to a GPS coordinate receiver.

The target beacon can for example be attached to a skier or a mountaineer or a person making a journey in a difficult to access environment such as a mountain, a forest or an urban environment.

The target tag can also be attached to a wild animal moving in an environment that is difficult to access or even to a lost or stolen object that one wishes to locate.

The target beacon may contain a transceiver component which transmits the radio signal such as an antenna and in particular an omnidirectional antenna for example.

The identification information included in the target radio signal and in the location signal can designate a unique identifier relating to the target beacon such as a MAC address for example.

The location information can for example designate GPS coordinates relating to the target beacon included in the location signal.

Advantageously, the radio signal emitted or received by the target beacon has a range of several kilometers and for example a range greater than 3 kilometers.

The detection device can also contain a transceiver component which receives the radio signal such as an omnidirectional antenna for example.

The search system for a target tag may further include:

An intermediate beacon configured to detect a location signal transmitted by the target beacon, and to transmit an intermediate signal comprising location information of the target beacon when said detection device is within the transmission range of the intermediate beacon.

The intermediate beacon may include a memory circuit capable of storing the location information of the target beacon included in the location signal while waiting for its retransmission.

The sensing device may be configured to measure a target distance between the sensing device and the target beacon based on a calculation of a target radio signal propagation time between the target beacon and the sensing device.

According to one possibility, the detection device is included in an aerodyne.

The aerodyne can for example designate a helicopter, a drone or an aircraft.

The detection device F can be connected to a guidance interface.

The guidance interface can be connected to a magnetic compass and a GPS coordinate receiver.

The guidance interface can be visual, and in this case it can be a visualization device, it can also be audio or textual.

According to one embodiment, the target beacon comprises a coordinate receiver and in particular a GPS coordinate receiver.

Advantageously, the target beacon can be powered by a rechargeable battery giving it an autonomy of several days.

When the GPS receiver of the target beacon is unable to receive satellite signals necessary for calculating a position of said GPS receiver of the target beacon and therefore when the GPS coordinates of the target beacon are not known at a defined time, the beacon target transmits its last known GPS coordinates as well as an age of these known GPS coordinates, in other words the precise instant at which a calculation of the last known GPS coordinates of the target beacon took place.

Detailed description

The invention will be better understood with the aid of the detailed description which is set out below with regard to the appended drawings in which:

[Fig.1] is a flowchart which shows different exchanges of radio signals between a target beacon to be searched for and a detection device during execution of a first mode of implementation of a method for searching for the target beacon .

[Fig .2] is a flowchart which shows different exchanges of radio signals between the target beacon to be searched for and the detection device during execution of a second mode of implementation of the method for searching for the target beacon. [Fig.3] is a flowchart which shows different exchanges of radio signals between the target beacon to be searched, the detection device and an intermediate beacon during an execution of a third mode of implementation of the search method of the target tag.

[Fig.4] is a schematic representation of a target beacon search system of Figures 1, 2 and 3 showing the target beacon to be searched and the detection device.

[Fig.5] is a schematic representation of the target beacon search system, the search system comprising an intermediate beacon and implementing the method described in Figure 3.

[Fig.6] is a schematic representation showing on the right of the figure a path of movement of the detection device and a position of the target beacon to be searched, and on the left of the figure a display of a position of the detection device and of a distance separating it from the target beacon to be searched.

[Fig.7] is a schematic representation showing on the right the passage of the detection device next to the target beacon and on the left the display of the position of the corresponding device.

[Fig.8] is a schematic representation showing a deviation in the trajectory of the detection device with a view to returning to the position of the target beacon, and on the left the display of the position of the corresponding device.

[Fig.9] is a schematic representation showing the continuation of the deviation in the trajectory of the detection device of FIG. 8 with a view to returning to the position of the target beacon, and on the left the display of the position of the corresponding device.

[Fig.10] is a schematic representation showing the continuation of the trajectory of the detection device of Figures 8 and 9 when the detection device joins the position of the target beacon, and on the left the display of the position of the corresponding device.

In the detailed description which will follow of the figures defined above, the same elements or the elements performing identical functions may retain the same references so as to simplify the understanding of the invention.

Description of the research process

The invention relates to a method for searching for a target beacon BC by a detection device F capable of detecting a target radio signal SC emitted by the target beacon, the target beacon BC being attached to an object or to a living being to be searched .

The different stages of the research process are presented in the figures

1, 2 and 3.

The target beacon BC can first perform an EBC2 transmission of an M-Coord location signal comprising location information for the target beacon BC as shown in Figures 1, 2 and 3. If the detection device F is within the transmission range P of the target beacon BC, this device receives in a step EF2 the location signal M-Coord comprising information on the location of the target beacon BC, followed by a transmission EF3 by the detection device F of a command signal M-ord comprising an order to send the target radio signal SC from the target beacon BC to the detection device F.

The location signal M-coord may contain location information as well as information identifying the target beacon BC.

The command signal M-ord can comprise a command for the operation of the target beacon BC as a transmitter of the target radio signal SC in addition to the order to transmit the target radio signal SC of the target beacon BC. The location signal M-Coord may for example contain an identifier of the target beacon BC such as a MAC address, geolocation coordinates of the target beacon BC such as GPS coordinates and a precise instant at which the last known GPS coordinates of the BC target beacon among others.

The command signal M-ord designates a signal sent by the detection device F by which the detection device F commands the target beacon BC to configure itself as a radiofrequency transmitter so that the target beacon BC can transmit the target radio signal SC.

According to one mode of implementation, a LORA protocol for long range in English is used. The reception of the target radio signal SC corresponds to a response from the target beacon BC to the emission of a command signal M-ord by the detection device F. The calculation of the distance takes into account time information relating to the transmission of the request signal and reception of the target radio signal SC.

In another mode of implementation, the target radio signal SC may not include information identifying the target beacon BC. The identification of the target beacon is carried out based on the temporal correspondence between the transmission of the request signal and the reception of the target radio signal SC.

Then, as shown in Figures 1, 2 and 3, the target beacon BC carries out the reception EBC3 of a command signal M-ord coming from the detection device F comprising a command for the operation of the target beacon BC as a transmitter of the target radio signal SC and an order to transmit the target radio signal to the detection device F, followed by an emission EBC4 by the target beacon BC of the target radio signal SC.

The target radio signal SC is then received by the detection device F during a reception step EF10 of a target radio signal SC emitted by the target beacon BC, and the detection device F determines a value of target distance EF11 between the detection device F and the target beacon BC on the basis of a calculation of a propagation time of the radio signal between the target beacon BC and the detection device F. The detection device F then performs a comparison EF12 of the target distance value and a reference target distance value.

If the value of the target distance is less than the value of the reference target distance or if the value of the reference target distance is not determined, then the detection device proceeds to the determination EF13 of the value of the distance reference target Rmin according to the value of the target distance. The detection device F also proceeds to a determination EF14 of a reference position Pmin as a function of a position of the detection device F, then to a determination EF15 of a location zone Z of the target beacon BC with respect to the position of the detection device F as a function of the reference position and the reference target distance.

The location zone Z presented in FIG. 6 can for example comprise a circle centered on the reference position Pmin and having a radius defined as a function of the reference target distance Rmin.

The determination EF13 of the value of the target distance as a function of the value of the reference target distance Rmin can comprise an assignment of the value of the target distance to the value of the reference target distance Rmin. In this case, the reference target distance Rmin represents the minimum distance measured between the detection device F and the target beacon BC since the start of the search for the target beacon BC.

The determination EF14 of a reference position Pmin as a function of a position of the detection device F may comprise the assignment of the position of the detection device to the reference position Pmin.

According to an implementation mode presented in FIG. 1 in which a human user such as a rescuer controls the detection device F, the method for searching for a target beacon BC can further comprise a step of supplying EF16 by the detection device. detection F of an indication on a user interface concerning the reference position Pmin and the location zone Z.

The provision EF16 of an indication on a user interface concerning the reference position Pmin and the location zone Z comprises a display of a representation of the reference position Pmin and/or of the location zone Z on a display device .

An example of the display representing the reference position Pmin and/or the location zone Z on a display device is shown in Figures 6 to 10. Figures 6 to 10 can represent a search for the target beacon by the detection device included in an aerodyne. According to one example, the rescuer piloting the detection device F chooses any piloting direction. He can also choose a steering direction leading to the last known GPS coordinates of the target beacon BC.

Thus, one can see on the right of FIG. 6 a straight trajectory T1 of the detection device F which is heading towards a position A of the target beacon BC. On the left, the corresponding display on the display device shows a displacement of the detection device F towards the north N with a position reticle O of the detection device F centered on the location zone Z. As long as the distance separating the device of detection F of the target beacon BC decreases, the detection device F maintains its straight trajectory T1. If the distance separating the detection device F from the target beacon BC increases, then the rescuer performs a U-turn in order to approach the position A of the target beacon BC.

The display device permanently displays the position of the detection device F as well as the reference target distance Rmin. As long as the distance separating the detection device F from the target beacon BC decreases, the position reticle O and the reference position Pmin coincide on the display device.

At a given instant presented in FIG. 7, the detection device F, continuing its movement in the trajectory T 1 , exceeds the position A of the target beacon: the target distance then passes through a minimum equivalent to the reference target distance Rmin and starts to increase again. On the display device, the reticle of position O and reference position Pmin no longer coincide. The rescuer can then observe that the reticle at position O has exceeded the reference target distance Rmin. The BC target beacon is somewhere within the circle of reference target distance radius Rmin, without the rescuer knowing in which direction the BC target beacon is.

When the position reticle O is in intersection with the circle whose radius is the reference target distance Rmin, the rescuer modifies the trajectory of the detection device F to engage it on a circular trajectory T2 and which coincides as best as possible with the circle having as radius the reference target distance Rmin. The rescuer can for example modify the trajectory of the detection device F by making a quarter turn. The trajectory T2 brings the detection device F closer to the target beacon BC as is the case in figure 8.

As a result, the position reticle O and the reference position Pmin again coincide on the display of the display device as is the case in FIG. 9 since the position of the detection device F corresponds to the reference position Pmin in this case, and that the target distance corresponds to the reference target distance Rmin.

The rescuer maintains the trajectory T2 of the detection device without deviating as long as the target distance decreases and the position reticle O and the reference position Pmin coincide. When on the display of the display device, the position reticle O and the reference position Pmin no longer coincide, the rescuer can for example make a turn in the trajectory T2 of the detection device F as soon as the position reticle O crosses the circle of radius the reference target distance Rmin so that the position reticle O describes part of the circle of radius the reference target distance Rmin.

The piloting maneuvers of the detection device F presented in FIGS. 6 to 10 can be repeated in order to obtain a spiral trajectory T2 like that of FIG. 10, and this in order to bring the detection device F to a position substantially vertically from position A of the BC target beacon.

Advantageously, the search method described does not require any landmarks on the ground, and can be implemented even in the event of poor visibility for the rescuer.

Advantageously, if the trajectory of the detection device is constrained by obstacles or weather conditions, the fact that the display of the display device permanently shows the reference target distance Rmin allows the pilot of the detection device F to return to the location zone of the target beacon BC regardless of the direction in which the detection device F moves.

Advantageously, the search method described can allow a quick and efficient search by having recourse to a reduced number of components such as the target beacon BC and the detection device F.

Advantageously, the search method described can be implemented in the case where the person or the object to be searched for is buried in the snow for example or in a closed location such as under a rock or under cover of dense vegetation, without require additional geolocation means for the BC target beacon. In other words, the search method described can be implemented even if the target beacon BC does not have a GPS receiver.

Advantageously, the search method described makes it possible to begin the search for the target beacon BC several kilometers away and to obtain, at the end of the search method described, the position of the target beacon BC with metric precision.

Advantageously, the search method described is systematic and therefore easily automatable.

Advantageously, the search method described can be implemented with omnidirectional antennas requiring no condition of direction of arrival of the target radio signal SC and easily integrated into portable equipment.

According to another mode of implementation presented in FIG. 2 in which the detection device is controlled automatically, by computer software for example, in particular as when the detection device is included in a drone, then the method for searching for a target beacon BC further comprises a step EF17 of controlling the displacement of the detection device F along a trajectory T1 of displacement in a straight line if the value of the target distance is less than the value of the target distance reference Rmin, as well as a step EF17' for controlling the displacement of the detection device F along a trajectory T2 guided on the circle centered on the reference position Pmin and having a radius defined as a function of the reference target distance Rmin if the target distance value is greater than the reference target distance value Rmin.

Distress mode and intermediate beacon

Before the execution of the step of transmitting an M-Coord location signal EBC2, the target beacon BC can carry out a selection EBC1 of an operating mode of the target beacon BC in the group comprising a first mode so-called normal operating mode and a second so-called distress operating mode.

The selection EBC1 of an operating mode of the target beacon in the group comprising a first so-called normal operating mode and a second so-called distress operating mode can be done for example on instructions from the user.

The selection EBC1 of an operating mode of the target beacon BC in the group comprising a first operating mode called normal and a second operating mode called distress can be done:

The first so-called normal mode of operation is presented in FIG. 4 and designates a mode of operation of the target beacon in which the target beacon BC transmits a location signal M-coord comprising information on the location of the target beacon BC which can be received by the detection device F when the detection device is within the transmission range of the target beacon BC.

The second so-called distress operating mode is presented in FIG. 5 and designates an operating mode of the target beacon BC in which an intermediate beacon B1 is capable of retransmitting the location signal M-coord of the target beacon BC. This distress mode allows the detection device F to receive the M-coord location signal from the target beacon BC without being within the transmission range of the target beacon BC.

Thus, the target beacon BC transmits the location signal M-coord which may include a distress marker indicating to the intermediate beacon Bl which receives the signal location M-coord of the target beacon BC to retransmit it. This allows the detection device F to receive the location signal M-coord either directly or through the intermediate beacon Bl which provides a relay between the target beacon BC and the detection device F.

Thus, the method for searching for a target beacon BC may further comprise a step of receiving EF1' an intermediate radio signal SI emitted by the intermediate beacon B1 comprising information on the location of the target beacon BC when said detection device F is within the transmission range P of the intermediate beacon B1, as well as an initialization step EF2' of a reference position Pmin according to the location information of the target beacon BC.

The location information received from the target beacon BC can designate the last location information sent by the target beacon BC, for example before the target beacon BC stops transmitting the target radio signal SC. According to one possibility, the steps of reception EF1' of an intermediate radio signal SI transmitted by the intermediate beacon Bl and of initialization EF2' of a reference position Pmin according to the location information of the target beacon BC can be repeated several times.

Description of the search system

The invention further relates to a system for searching for a BC target beacon intended to be attached to an object or to a living being to be searched, comprising the BC target beacon intended to be attached to an object or to a living being and emitting in the transmission range P of the target beacon BC the target radio signal SC comprising the identification information of the target beacon BC, the target beacon BC being configured to implement the search method described above.

The target beacon BC shown in FIGS. 4 and 5 can for example be attached to a skier or a mountaineer or a person making a journey in a difficult to access environment such as a mountain, a forest or an urban environment.

The BC target beacon can also be attached to a wild animal moving in an environment that is difficult to access or to a lost or stolen object that one wishes to locate.

Advantageously, the transmission range P of the target beacon BC can be several kilometers and it can be greater than 3 kilometers for example.

According to one possibility, the target beacon BC contains a transmitter-receiver component which transmits the radio signal like an antenna and in particular an omnidirectional antenna for example.

The identification information included in the target radio signal SC and in the location signal can designate a unique identifier relating to the target beacon BC such as a MAC address for example and the location information can for example designate GPS coordinates relating to the target beacon BC included in the location signal.

The target beacon BC may comprise a coordinate receiver and in particular a GPS coordinate receiver.

Advantageously, the target beacon BC can be powered by a rechargeable battery giving it an autonomy of several days.

According to one possibility, when the GPS receiver of the target beacon BC is unable to connect to a navigation network and therefore when the GPS coordinates of the target beacon BC are not known at a defined instant, the target beacon BC transmits its last known GPS coordinates as well as an age of these known GPS coordinates, in other words the precise instant at which a calculation of the last known GPS coordinates of the target beacon BC took place.

The BC target beacon search system further comprises a detection device F shown in Figures 4 and 5 and capable of detecting the target radio signal SC emitted by the target beacon BC when said detection device F is within range. transmission P of the target beacon BC, the detection device F comprising a calculation unit implementing the method described above.

The detection device F may contain a transmitter-receiver component which receives the target radio signal SC such as an omnidirectional antenna for example.

According to one possibility, the detection device F is configured to measure a target distance between the detection device F and the target beacon BC on the basis of a calculation of a propagation time of the target radio signal SC between the target beacon BC and the detection device F.

The detection device F can be included in an aerodyne such as a helicopter, a drone or an aircraft. The detection device F can also be included in a vehicle moving normally on the ground such as a car.

According to one possibility, the detection device can be worn by a human user moving on foot.

The detection device F can be connected to a guidance interface, the guidance interface itself being connected to a magnetic compass and to a GPS coordinate receiver.

The guidance interface can be visual, and in this case it can be a display device such as a screen of a tablet for example, it can also be audio or textual.

According to one embodiment, the system for searching for a target beacon BC can also comprise an intermediate beacon B1 shown in FIG. 5 configured to detect the location signal M-coord transmitted by the target beacon BC, and for transmitting an intermediate signal SI comprising the location information of the target beacon BC when said detection device F is within the transmission range P of the intermediate beacon Blu.

The intermediate beacon B1 may comprise a memory circuit capable of storing the location information of the target beacon BC included in the location signal M-coord while awaiting its retransmission.

Although the invention has been described in conjunction with specific embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

Claims

1. Method of searching for a target beacon (BC) attached to an object or a living being to be searched, said search method being executed by a detection device (F) capable of detecting a target radio signal (SC) emitted by the target tag, the search method comprising the following steps:

Reception (EF10) of a target radio signal (SC) emitted by the target beacon (BC) comprising information identifying the target beacon when said detection device (F) is within the transmission range (P) of the target tag;

Determination of a target distance value (EF11) between the detection device (F) and the target beacon (BC) on the basis of a calculation of a propagation time of the radio signal between the target beacon (BC) and the detection device (F);

Comparison of the target distance value and a reference target distance value (EF12);

If the target distance value is less than the reference target distance value or if the reference target distance value is not determined: i. Determination (EF13) of the value of the reference target distance (Rmin) according to the value of the target distance; ii. Determination (EF14) of a reference position (Pmin) as a function of a position of the detection device (F);

Determination (EF15) of a location zone of the target beacon (BC) with respect to the position of the detection device (F) according to the reference position and the reference target distance.

2. A method of searching for a target beacon (BC) according to claim 1, in which the detection device (F) is connected to a guidance interface, itself connected to a magnetic compass and to a GPS coordinate receiver .

3. Method for searching for a target beacon (BC) according to one of claims 1 or 2, in which the location zone (Z) comprises a circle centered on the reference position (Pmin) and having a radius defined in function of the reference target distance (Rmin).

4. Method for searching for a target beacon (BC) according to one of the preceding claims, in which the determination (EF13) of the value of the target distance as a function of the reference target distance value (Rmin) includes an assignment of the target distance value to the reference target distance value (Rmin).

5. Method for searching for a target beacon (BC) according to one of the preceding claims, in which the determination (EF14) of a reference position (Pmin) as a function of a position of the detection device (F) includes the assignment of the position of the detection device to the reference position (Pmin).

6. Method for searching for a target beacon (BC) according to one of the preceding claims, further comprising the following steps:

Reception (EF2) of a location signal (M-Coord) comprising information on the location of the target beacon (BC) when the detection device (F) is within the transmission range (P) of the target beacon ( BC);

Emission (EF3) of a command signal (M-ord) comprising an order to transmit the target radio signal (SC) from the target beacon (BC) to the detection device (F);

7. Method for searching for a target beacon (BC) according to one of the preceding claims, further comprising the following steps:

If the value of the target distance is less than the value of the reference target distance (Rmin), control (EF17) of the movement of the detection device (F) along a trajectory (T1) of movement in a straight line;

If the value of the target distance is greater than the value of the reference target distance (Rmin), command (EF17') to move the detection device (F) along a trajectory (T2) guided on the circle centered on the position reference (Pmin) and having a radius defined as a function of the reference target distance (Rmin).

8. Method for searching for a target beacon (BC) according to one of the preceding claims, further comprising the following step:

Provision (EF16) of an indication on a user interface concerning the reference position (Pmin) and the location zone (Z).

9. A method of searching for a target beacon (BC) according to claim 8, in which the provision (EF16) of an indication on a user interface concerning the reference position (Pmin) and the location zone (Z) comprises a display of a representation of the reference position (Pmin) and/or of the location zone (Z) on a display device.

10. Method for searching for a target beacon (BC) according to one of the preceding claims, further comprising the following step:

Reception (EF1') of an intermediate radio signal (SI) emitted by an intermediate beacon (Bl) comprising information on the location of the target beacon (BC) when said detection device (F) is within the transmission range ( P) of the intermediate beacon (B1);

11. Beacon search method according to one of the preceding claims, further comprising the following step:

Initialization (EF2') of a reference position (Pmin) according to the location information of the target beacon (BC)

12. Method of searching for a target beacon (BC) attached to an object or a living being to be searched, said search method being executed by the target beacon (BC) transmitting within a transmission range (P) of the target beacon (BC) a target radio signal (SC) capable of being detected by a detection device (F), the search method comprising the following steps:

Reception (EBC3) of a command signal (M-ord) originating from the detection device (F) comprising a command to operate the target beacon (BC) as a transmitter of the target radio signal (SC) and an order to transmission of the target radio signal to the detection device (F);

Emission (EBC4) of the target radio signal (SC) comprising information identifying the target beacon (BC).

13. A method of searching for a target beacon (BC) according to claim 12, in which the detection device (F) is connected to a guidance interface, itself connected to a magnetic compass and to a GPS coordinate receiver .

14. Method for searching for a target beacon (BC) according to one of claims 12 or 13 further comprising the steps of:

Selection (EBC1) of an operating mode of the target beacon (BC) from the group comprising a first operating mode called normal and a second operating mode called distress;

Emission (EBC2) of a location signal (M-Coord) comprising information on the location of the target beacon (BC).

15. System for searching for a target beacon (BC) intended to be attached to an object or to a living being to be searched, comprising: the target beacon (BC) intended to be attached to an object or to a living being and emitting within a transmission range (P) of the target beacon (BC) a target radio signal (SC) comprising information identifying the the target beacon (BC), the target beacon (BC) being configured to implement the method according to claims 12 to 14; a detection device (F) capable of detecting the target radio signal (SC) emitted by the target beacon (BC) when said detection device (F) is within the transmission range (P) of the target beacon (BC) , the detection device (F) comprising a calculation unit implementing the method according to claims 1 to 11.

16. System for searching for a target beacon (BC) according to claim 15, in which the detection device (F) is connected to a guidance interface, itself connected to a magnetic compass and to a GPS coordinate receiver .

17. System for searching for a target beacon (BC) according to one of claims 15 or 16 further comprising:

An intermediate beacon (Bl) configured to detect a location signal (M-coord) transmitted by the target beacon (BC), and to transmit an intermediate signal (SI) comprising location information of the target beacon (BC) when said detection device (F) is within the transmission range (P) of the intermediate beacon (Bl).

18. System for searching for a target beacon (BC) according to claim 17, in which the intermediate beacon (B1) comprises a memory circuit capable of storing the location information of the target beacon (BC) included in the location signal (M-coord).

19. System for searching for a target beacon (BC) according to one of claims 15 to 18, in which the detection device (F) is configured to measure a target distance between the detection device (F) and the target beacon. (BC) based on a calculation of a propagation time of the target radio signal (SC) between the target beacon (BC) and the detection device (F).

20. System for searching for a target beacon (BC) according to one of claims 15 to 19, in which the detection device (F) is included in an aerodyne.

21. System for searching for a target beacon (BC) according to one of claims 15 to 20, in which the target beacon (BC) comprises a coordinate receiver and in particular a GPS coordinate receiver.