Device for detecting a person in at least one predetermined zone around a motor vehicle

Abstract

The invention relates to a device (10) for detecting a person in at least one predetermined zone around a motor vehicle, the device (10) comprising an electronic control unit (110), a communication block (120), a transceiver antenna (130) and a detection block (140) configured to receive signals originating from the transceiver antenna (130), to subtract the predetermined frequency of the oscillator (128) from the frequency of the received signals, to filter the signals in a predetermined detection frequency band and to detect the presence of a person in the at least one predetermined zone around the vehicle when the frequency of the filtered signals is within the predetermined detection frequency band and the amplitude of the filtered signals exceeds a predetermined threshold.

Description

DESCRIPTION TITLE: Device for detecting a person in at least one predetermined area around a motor vehicle [Technical field]

[0001] The present invention relates to the field of automobiles and more particularly concerns a device for detecting a person in at least one predetermined area around a motor vehicle. [Prior art]

[0002] The detection of the presence of a human being near a motor vehicle can be carried out in a known manner at very short distances or at longer distances.

[0003] At very short distances, the proximity sensor is of the capacitive or inductive type and detects a part of the user's body when the user is very close to the sensor, thus varying its capacitance or inductance.

[0004] This type of sensor is commonly used in vehicle door handles to unlock the doors when the user approaches the handle within a short distance, for example, less than 10 cm. The user has been previously authenticated through a message exchange between the vehicle and a device worn by the user, such as a key, badge, or smartphone. In the case of a smartphone, authentication can be performed via message exchange using the Bluetooth® Low Energy (BLE) communication protocol. However, the BLE communication protocol itself does not perform the detection.

[0005] At longer distances, greater than 10 cm, the user's body can be detected using known methods with wave-based sensors, such as radio frequency or infrared, or with cameras. However, these sensors are energy-intensive and prone to dust accumulation. Furthermore, camera systems are particularly expensive.

[0006] At longer distances, user body detection can also be achieved using a known method: emitting waves with an antenna mounted in the vehicle and measuring the power of the waves reflected off the user's body or the time of flight of the reflected waves. In particular, the Ultra Wide Band (UWB) standard is known to be used. This standard has both a communication mode to allow the vehicle to exchange messages with the user's smartphone, notably for authentication, and a detection mode that operates by calculation of the time of flight of reflected waves, providing significant accuracy, on the order of centimeters.

[0007] However, UWB equipment proves to be expensive, energy-intensive and too precise for some applications that do not require high precision, for example no less than 20 cm of accuracy.

[0008] A simple, reliable and effective solution that addresses at least some of these drawbacks would therefore be advantageous. [Description of the invention]

[0009] To this end, the invention first relates to a device for detecting a person in at least one predetermined area around a motor vehicle, said device comprising an electronic control unit, a communication block connected to said electronic control unit, and a transmit-receive antenna connected to said communication block, the communication block being configured to generate, on command from the electronic control unit, signals comprising communication frames to be transmitted via the transmit-receive antenna and to extract useful data from the communication frames received via the transmit-receive antenna and transmit them to the electronic control unit, the communication block comprising an oscillator oscillating at a predetermined fixed frequency within the 2.4 GHz band,said device being characterized in that it further comprises a detection block connected to both the transmit-receive antenna and the oscillator of the communication block, said detection block being configured to receive signals from the transmit-receive antenna, to subtract the predetermined frequency of the oscillator from the frequency of the received signals, to filter the signals into a predetermined detection frequency band, and to detect the presence of a person in said at least one predetermined area around the vehicle when the frequency of the filtered signals is within the predetermined detection frequency band and the amplitude of the filtered signals exceeds a predetermined threshold.

[0010] By "2.4 GHz band", we mean the UHF band between 2.4 and 2.495 GHz which notably accommodates BLE (Bluetooth® Low Energy) frequencies.

[0011] Adding a detection block to the standard BLE communication block enables both communication between the user equipment and the vehicle, as well as several presence detection functions within the vehicle, using the BLE protocol. In other words, the invention allows the use of a single device for both communication and presence detection, using the BLE protocol. The block of Because detection can be implemented with simple hardware components, the device is inexpensive, energy-efficient, and can be advantageously added simply to an existing BLE communication block.

[0012] According to one aspect of the invention, the predetermined detection frequency band is between 5 and 20 Hz in order to detect human movements against other movements.

[0013] Preferably, the predetermined detection frequency band is between 10 and 15 Hz in order to detect human movements even more accurately.

[0014] In one embodiment, the device includes a first switch, preferably two-position, connecting the oscillator of the communication block to the detection block.

[0015] Advantageously, the device includes a second switch, preferably two-position, connecting the transmit-receive antenna to the detection block.

[0016] The first switch and the second switch allow the detection block to be connected in order to switch to detection mode to detect user equipment or to disconnect the detection block in order to be in communication mode only to communicate with user equipment, including authenticated user equipment.

[0017] Advantageously still, the detection block is configured to receive from the electronic control unit a command to simultaneously open or simultaneously close the first switch and the second switch and to control the first switch and the second switch either open or close according to said command received from the electronic control unit.

[0018] In one form of implementation, the communication block includes:

[0019] - a BLE communication module connected to said electronic control unit and configured to generate signals comprising BLE communication frames from payload data provided by the electronic control unit and to extract payload data from BLE communication frames contained in signals received by the transmit-receive antenna and provide the extracted payload data to the electronic control unit,

[0020] - a modulator connected at the input of said communication module and configured to modulate the signals containing the BLE communication frames generated by the BLE communication module,

[0021] - a radio frequency transmit mixer connected to the output of said modulator and configured to add the predetermined frequency of the oscillator to the frequency of the modulated signals,

[0022] - a radio frequency transmitting amplifier connected on one side to the output of the radio frequency transmitting mixer and on the other side to said transmit-receive antenna and configured to amplify the signal received from the radio frequency transmitting mixer,

[0023] - a radio frequency receiving amplifier connected at the input to the transmitting-receiving antenna and configured to amplify the signal received from the transmitting-receiving antenna,

[0024] - a radio frequency receiver mixer connected to the output of the radio frequency receiver amplifier and configured to add the predetermined oscillator frequency to the frequency of the received signals,

[0025] - a demodulator connected to the output of the receiving radio frequency mixer and configured to demodulate the signals supplied by the receiving radio frequency mixer, and whose output is connected to the communication module,

[0026] - the oscillator being connected to the transmitting radio frequency mixer and the receiving radio frequency mixer.

[0027] In one embodiment, the detection block comprises a radio frequency detector mixer, a bandpass filter, a baseband amplifier, a control module, and a comparator, the radio frequency detector mixer being configured to receive signals from the transmit-receive antenna, to subtract their frequency from the predetermined frequency of the oscillator, and to transmit the signals at a frequency suitable for the bandpass filter, the bandpass filter being configured to filter the signal from the radio frequency detector mixer onto a predetermined frequency band, the baseband amplifier being configured to amplify the signal filtered by the bandpass filter, the control module being configured to control the baseband amplifier and to deliver a threshold voltage signal that can take one or more different values.The comparator is configured to receive, on a first input, the signal supplied for the baseband amplifier and, on a second input, the threshold voltage signal supplied by the control module, to compare the values ​​of the signal received on the first input and the signal received on the second input, and to provide an output signal representing the difference in voltage values ​​between the two signals.

[0028] Even more advantageously, the first switch is connected on one side to the oscillator and on the other side to the radio frequency detector mixer.

[0029] Even more advantageously, the second two-position switch is connected on one side to the transmit-receive antenna and on the other side to the radio frequency detector mixer.

[0030] In one embodiment, the detection block further includes a detection module connected to the output of the comparator and configured to detect, from the signal supplied by the comparator, the presence of a person in a first predetermined zone around the vehicle, said first zone extending outside the vehicle, or in a second predetermined zone included within the first predetermined zone and located inside the vehicle.

[0031] Alternatively, the electronic control unit is connected to the comparator output and is configured to detect, from the signal provided by the comparator, the presence of a person in a first predetermined zone around the vehicle, said first zone extending outside the vehicle, or in a second predetermined zone included within the first predetermined zone and located inside the vehicle.

[0032] The invention also relates to a motor vehicle comprising a device as previously described.

[0033] The invention also relates to a method for detecting a person in at least one predetermined area around a motor vehicle as described above, said method comprising the steps of:

[0034] - command, by the electronic control unit, of the communication module to transmit signals via the transmit-receive antenna,

[0035] - reception, by the transmitting-receiving antenna, of reflected emitted signals,

[0036] - subtraction of the predetermined oscillator frequency from the frequency of the received signals,

[0037] - filtering of signals within a predetermined detection frequency band,

[0038] - detection of the presence of a person in said at least a predetermined zone around the vehicle the frequency of the filtered signals is within the predetermined detection frequency band and the amplitude of the filtered signals exceeds a predetermined threshold.

[0039] In one embodiment, the device includes the first switch and the second switch; the method includes, prior to the control step, by the electronic control unit, of the communication module to emit signals via the transmit-receive antenna, the steps of sending, by the electronic control unit, to the control module, a command to simultaneously close the first switch and the second switch, of receiving, by the control module, said closing command, and of commanding, by the control module, the simultaneous closing of the first switch and the second switch.

[0040] The invention also relates to a computer program product characterized in that it comprises a set of program code instructions which, when executed by one or more processors, configure the processor(s) to implement a process as described above. [Description of the drawings]

[0041] Other features and advantages of the invention will become apparent upon reading the following description. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:

[0042] [Fig 1] Figure 1 schematically illustrates an example of a vehicle according to the invention.

[0043] [Fig 2] Figure 2 schematically illustrates one embodiment of the device according to the invention.

[0044] [Fig 3] Figure 3 schematically illustrates one embodiment of the process according to the invention. [Description of the embodiments]

[0045] Figure 1 illustrates an example of a motor vehicle 1 comprising a device 10 according to the invention.

[0046] Device 10 enables the detection of a person near vehicle 1, in a first predetermined detection zone Z1, from signals defined according to the Bluetooth® Low Energy (BLE) protocol.

[0047] Preferably, as described in the example below, the device 10 also allows the detection of the intrusion of a person 2 into the passenger compartment of the vehicle 1 or more precisely into a second predetermined detection zone Z2 included de facto in the first detection zone Z1.

[0048] With reference to Figure 2, the device 10 comprises an electronic control unit 110, a communication block 120, a transmit-receive antenna 130 and a detection block 140.

[0049] The communication block 120 includes a communication module 121, a modulator 122, a transmit radio frequency mixer 123, a transmit radio frequency amplifier 124, a receive radio frequency amplifier 125, a receive radio frequency mixer 126, a demodulator 127 and an oscillator 128.

[0050] The detection block 140 includes a radio frequency detector mixer 141, a bandpass filter 142, a baseband amplifier 143, a control module 144, a comparator 145 and a presence detection module 146.

[0051] In the illustrated embodiment, the device 10 further includes a first switch 150, connected on one side to the oscillator 128 and on the other side to the radio frequency detector mixer 141, and a second switch 160, connected on one side to the transmit-receive antenna 130 and on the other side to the radio frequency detector mixer 141.

[0052] Electronic control unit 110

[0053] The electronic control unit 110 is connected on one side to the communication module 121 and on the other side to the control module 144.

[0054] The electronic control unit 110 is configured to send useful data to the communication module 121 and to control the communication module 121 so that said communication module 121 generates signals comprising BLE communication frames including said useful data and transfers said signals to the modulator 122 for transmission by the transmit-receive antenna 130.

[0055] The electronic control unit 110 is configured to receive, from the communication module 121, useful data extracted from signals received by said communication module 121 via the transmit-receive antenna 130.

[0056] The electronic control unit 110 is configured to send commands to the control module 144, including to control the opening and closing of the first switch 150 and the second switch 160.

[0057] The electronic control unit 110 includes a processor capable of implementing a set of instructions to perform these functions.

[0058] Communication block 120

[0059] Communication Module 121

[0060] The communication module 121 is configured to, on command from said electronic control unit 110, generate signals comprising BLE communication frames by inserting useful data supplied by the electronic control unit 110 and to transmit said signals to the modulator 122.

[0061] The communication module 121 is configured to receive BLE communication frames from the demodulator 127, extract the useful data and transmit it to the electronic control unit 110 for processing.

[0062] Modulator 122

[0063] The modulator 122 is connected by its input to the communication module 121 in order to modulate the signals provided by the communication module 121 into a signal modulated according to the BLE protocol which it transmits to the radio frequency transmitter mixer 123.

[0064] Radio frequency transmission mixer 123

[0065] The transmit radio frequency mixer 123 is connected to the output of the modulator 122 and is configured to add the predetermined frequency of the oscillator 128 to the modulated signal so that the resulting signal can be transmitted by the transmit-receive antenna 130 on the 2.4 GHz band.

[0066] 124V Radio Frequency Transmitter Amplifier

[0067] The transmit radio frequency amplifier 124 is connected to the output of the transmit radio frequency mixer 123 and is configured to amplify the signal supplied by the transmit radio frequency mixer 123 and to supply it to the transmit-receive antenna 130.

[0068] 125 Radio Frequency Receiver Amplifier

[0069] The radio frequency receiver amplifier 125 is connected at the input to the transmit-receive antenna 130 and is configured to amplify the signal supplied by the transmit-receive antenna 130 before supplying it to the radio frequency receiver mixer 126.

[0070] Radio frequency receiving mixer 126

[0071] The radio frequency receiver mixer 126 is connected to the output of the radio frequency receiver amplifier 125 and is configured to add the predetermined frequency to the amplified signal so that the resulting signal can be demodulated by the demodulator 127.

[0072] Demodulator 127

[0073] The demodulator 127 is connected on one side to the output of the radio frequency receiving mixer 126 and on the other side to the communication module 121.

[0074] The demodulator 127 is configured to demodulate the signal received from the radio frequency receiving mixer 126 in order to allow the communication module 121 to extract the BLE communication frames.

[0075] Oscillator 128

[0076] The oscillator 128 is configured to generate an oscillating signal at a predetermined fixed frequency within the 2.4 GHz band, extending between 2.4 and 2.495 GHz.

[0077] The oscillator 128 is configured to provide the predetermined frequency signal to the transmitting radio frequency mixer 123 and the receiving radio frequency mixer 126 in order to enable them to respectively synchronize the frequency of the signals that said transmitting radio frequency mixer 123 and said receiving radio frequency mixer 126 receive to the predetermined fixed frequency modulo the frequency of the received signal.

[0078] Transmitting / receiving antenna 130

[0079] The transmit-receive antenna 130 is connected to the output of the transmit radio frequency amplifier 124, to the input of the receive radio frequency amplifier 125 and to the second switch 160.

[0080] The transmit-receive antenna 130 is configured to transmit the amplified signals provided by the transmit radio frequency amplifier 123 and to receive signals sent by entities communicating according to the BLE protocol with the device 10, including signals emitted by said transmit-receive antenna 130 and which have been reflected off objects or persons, and transmit them to the receive radio frequency amplifier 125 and to the second switch 160 when said second switch 160 is closed.

[0081] Detection block 140

[0082] Radio frequency detector mixer 141

[0083] The radio frequency detector mixer 141 is configured to receive the signal at the predetermined frequency supplied by the oscillator 128 via the first switch 150 when said first switch 150 is closed and the signals received by the transmit-receive antenna 130 when the second switch 160 is closed and to subtract the predetermined frequency of the oscillator 128 from the frequency of the signals received from the transmit-receive antenna 130 when the first switch 150 is closed.

[0084] To this end, in the example of Figure 2, the radio frequency detector mixer 141 receives the signal at the predetermined frequency supplied by the oscillator 128 and the signals received by the transmit-receive antenna at a common input point A and includes a diode D, connected between the common input point A and a ground M, and a stop coil L, connected between the common input point A and the bandpass filter 142 allows the high-frequency components of the signals received by the transmit-receive antenna 130 to be suppressed. The stop coil L filters and adapts to the operating frequency to obtain a resonant frequency around the 2.4 GHz band. Diode D mixes the local signal from the oscillator 128 with the signal received at the transmit-receive antenna 130 to produce a "low-frequency" signal available for motion detection.

[0085] 142 Bandpass Filter

[0086] The bandpass filter 142 is configured to filter the signal from the radio frequency detector mixer 141 over a predetermined frequency band, preferably 10 to 15 Hz, in order to isolate signals received from the transmit-receive antenna 40 that may correspond to human movements.

[0087] Baseband amplifier 143

[0088] Baseband amplifier 143 is configured to amplify the signal filtered by bandpass filter 142 to enable the detection of human presence in a predetermined area around vehicle 1 and / or within vehicle 1. Baseband amplifier 143 is a low-frequency amplifier. Using a low-frequency amplifier after the radio frequency detector mixer 141 improves the signal-to-noise ratio, thus enabling more effective and longer-range detection.

[0089] For example, if the electronic control unit 110 contains a digital block with a sensitivity limited to 1 millivolt, and the signal received after movement at 1 meter is 0.7 millivolts, then the electronic control unit 110 is unable to detect movement beyond 1 meter. The baseband amplifier 143 amplifies the signal by a factor, for example, 10, increasing the range to 5 meters instead of 1 meter. In another embodiment, the baseband amplifier 143 could be incorporated into the electronic control unit 110.

[0090] Control Module 144

[0091] The control module 144 is configured to receive control commands from the electronic control unit 110 in order to simultaneously control the first switch 150 and the second switch 160 either opening or closing.

[0092] The control module 144 is configured to control the first switch 150 and the second switch 160 either opening or closing according to the commands received from the electronic control unit 10.

[0093] The control module 144 is configured to control the baseband amplifier 143 with a control defining the amplification level allowing the predetermined detection zone to be defined around the vehicle 1.

[0094] The control module 144 is configured to deliver to the comparator 145 a threshold voltage signal which can take one or more different values ​​in order to determine the detection threshold corresponding to a predetermined detection zone around or in the vehicle 1.

[0095] Comparator 145

[0096] The comparator 145 is configured to receive on a first input the signal supplied for the baseband amplifier 143 and on a second input the threshold voltage signal supplied by the control module 144, to compare the values ​​of the signal received on the first input and the signal received on the second input and to provide an output signal representing the difference in voltage values ​​between the two signals.

[0097] Presence detection module 146

[0098] The presence detection module 146 is configured to detect the presence of a person in a first predetermined area around vehicle 1, extending for example up to 5 meters around vehicle 1, from the value of the signal provided by comparator 145 when said subtracted frequency is within a predetermined detection frequency band between 5 and 20 Hz and a first predetermined amplitude threshold.

[0099] The presence detection module 146 is configured to detect the intrusion of a person into a second predetermined zone included in the first predetermined zone and covering at least part of the passenger compartment of vehicle 1 when said subtracted frequency is included in a predetermined detection frequency band between 5 and 20 HZ and a second predetermined amplitude threshold.

[0100] In an alternative embodiment, the presence detection module 146 could be implemented by the electronic control unit 110.

[0101] First switch 150

[0102] The first switch 150 is a two-position radio frequency switch (open state or closed state) which is connected on one side to the oscillator 128 and on the other side to the radio frequency detector mixer 141.

[0103] The first switch 150 is controlled to open and close by the control module 144, either directly or via the second switch 160 as shown in Figure 2. Thus, the first switch 150 and the second switch 160 are either both open at the same time, or both closed at the same time.

[0104] When closed, the first switch 150 allows the transmission of the signal generated by the oscillator 60 to the radio frequency detector mixer 141.

[0105] When open, the first switch 150 prevents the transmission of the signal generated by the oscillator 60 to the radio frequency detector mixer 141.

[0106] Second switch 160

[0107] The second switch 160 is a two-position radio frequency switch (open or closed) connected on one side to the transmit-receive antenna 40 and on the other side to the radio frequency detector mixer 141.

[0108] The second switch 160 is controlled in opening and closing by the control module 144 of the detection block 140, either directly or via the first switch 150. Therefore, as mentioned above, the first switch 150 and the second switch 160 are either both open at the same time, or both closed at the same time.

[0109] When closed, the second switch 160 allows the transmission of signals received by the transmit-receive antenna 40 to the radio frequency detector mixer 141 of the detection block 140.

[0110] When open, the second switch 160 prevents the transmission of signals received by the transmit-receive antenna 40 to the radio frequency detector mixer 141.

[0111] Example of implementation (figure 3).

[0112] In a communication mode enabling the communication of data to a user device, for example a badge, a key or a smartphone, the electronic control unit 110 pre-commands the control module 144 to open the first switch 150 and the second switch 160 if said first switch 150 and said second switch 160 are closed.

[0113] Once the first switch 150 and the second switch 160 are open, the electronic control unit 110 commands, in a step E1, the communication module 121 to emit useful data which it communicates to it.

[0114] The communication module 121 then encapsulates the useful data in BLE communication frames in a step E2 and transmits them to the modulator 122 which integrates them into signals according to the BLE protocol in a step E3.

[0115] The modulator 122 transmits the signals to the transmit radio frequency mixer 123 which, in a step E4, modifies the frequency of the signals from the predetermined frequency provided by the oscillator 128 so that they can be transmitted by the transmit-receive antenna 130 in the BLE format in the 2.4 GHz frequency band.

[0116] The transmitting radio frequency mixer 123 then transmits the signals of suitable frequency to the transmitting radio frequency amplifier 124 which then amplifies, in a step E5, the signals so that they have enough power to be transmitted by the transmit-receive antenna 130 with a range of approximately 100 meters according to the BLE protocol.

[0117] During communication with user equipment, the transmit-receive antenna 130 transmits amplified signals in a stage E6 and receives signals sent by said user equipment in a stage E7.

[0118] Upon receiving a signal sent by a user device, the transmit-receive antenna 130 transmits the signal to the radio frequency receiver amplifier 125 which amplifies the signals in a step E8 so that they have enough power to extract the BLE data frames.

[0119] The radio frequency receiver amplifier 125 then transmits the amplified signals to the radio frequency receiver mixer 126 which in a step E9 then modifies their frequency by subtracting the frequency supplied by the oscillator 128 from the frequency of the received signals and then transmits the signals obtained to the demodulator 127.

[0120] In a step E10, the demodulator 127 demodulates the signals in a manner known per se and transmits them to the communication module 121 which extracts the BLE communication frames from the signals and then the useful data from the frames in a step E11 before transmitting the useful data to the electronic control unit 110 for processing.

[0121] To switch to detection mode, the electronic control unit 110 commands the control module 144 of the detection block 140 in a step E12 in order to that said control module 144 closes the first switch 150 and the second switch 160 in a step E13 and then controls the communication module 121 in a step E14 so that said communication module 121 commands the generation of signals via the modulator 122, the transmit radio frequency mixer 123, the transmit radio frequency amplifier 124 and the transmit-receive antenna 130 in a step E15. These signals may or may not contain useful data.

[0122] When they are reflected off a person or an object, part of these signals return to the transmit-receive antenna 130 which then transmits them to the radio frequency detector mixer 141 via the second switch 160 which is closed.

[0123] The radio frequency detector mixer 141 subtracts the predetermined frequency from the oscillator 128 in a step E16 and then transmits the signals to the bandpass filter 142 which filters them in a step E17 to extract only the signals in a frequency band corresponding to a reflection of the signals on a person, preferably in the 10-15 Hz band.

[0124] The baseband amplifier 143 then amplifies the filtered signals in a step E18 in order to determine the detection sensitivity and then transmits them to the comparator 145.

[0125] The comparator 145 compares, in a step E19, the received signals with the thresholds provided by the control module 144 and the presence detection module 146 detects, in a step E20, the presence of a person in the first detection zone around the vehicle when the signal amplitude exceeds a first threshold or an intrusion of a person in the second detection zone when the signal amplitude exceeds a second threshold, higher than the first threshold.

[0126] The communication method and the detection method can be implemented alternatively.

[0127] In another embodiment of the process, the device 10 is devoid of the first switch 150 and the second switch 160, the transmit-receive antenna 130 is connected directly to the radio frequency detector mixer 141 and the oscillator 128 is also connected directly to the radio frequency detector mixer 141.

[0128] The invention therefore makes it possible to use the BLE protocol to detect a person around or in the vehicle in a simple, fast and efficient way, in particular due to the simplicity of the detection block 140.

Claims

Demands

1. Device (10) for detecting a person (2) in at least one predetermined zone (Z1, Z2) around a motor vehicle (1), said device (10) comprising an electronic control unit (110), a communication block (120) connected to said electronic control unit (110), and a transmit-receive antenna (130) connected to said communication block (120), the communication block (120) being configured to generate, on command from the electronic control unit (110), signals comprising communication frames to be transmitted via the transmit-receive antenna (130) and to extract useful data from the communication frames received via the transmit-receive antenna (130) and transmit them to the electronic control unit (110), the communication block (120) comprising an oscillator (128) oscillating at a predetermined fixed frequency within the 2.4 GHz band,said device (10) being characterized in that it further comprises a detection block (140) connected to both the transmit-receive antenna (130) and the oscillator (128) of the communication block (120), said detection block (140) being configured to receive signals from the transmit-receive antenna (130), to subtract the predetermined frequency of the oscillator (128) from the frequency of the received signals, to filter the signals into a predetermined detection frequency band and to detect the presence of a person (2) in said at least one predetermined zone (Z1, Z2) around the vehicle (1) when the frequency of the filtered signals is within the predetermined detection frequency band and the amplitude of the filtered signals exceeds a predetermined threshold.

2. Device (10) according to claim 1, wherein the predetermined detection frequency band is between 5 and 20 Hz.

3. Device (10) according to the preceding claim, wherein the predetermined detection frequency band is between 10 and 15 Hz.

4. Device (10) according to any one of the preceding claims, said device comprising a first switch (150) connecting the oscillator (128) of the communication block (120) to the detection block (140).

5. Device (10) according to the preceding claim, said device (10) comprising a second switch (160) connecting the transmit-receive antenna (130) to the detection block (140).

6. Device (10) according to the preceding claim, wherein the detection block (140) is configured to receive from the electronic control unit (110) a command to simultaneously open or simultaneously close the first switch (150) and the second switch (160) and to control the first switch (150) and the second switch (160) either opening or closing according to said command received from the electronic control unit (110).

7. Device (10) according to any one of the preceding claims, wherein the communication block (120) comprises: - a BLE communication module (121) connected to said electronic control unit (110) and configured to generate signals comprising BLE communication frames from payload data provided by the electronic control unit (110) and to extract payload data from BLE communication frames contained in signals received by the transmit-receive antenna (130) and provide the extracted payload data to the electronic control unit (110), - a modulator (122) connected at the input of said communication module (121) and configured to modulate the signals containing the BLE communication frames generated by the BLE communication module (121), - a radio frequency transmit mixer (123) connected to the output of said modulator (122) and configured to add the predetermined frequency of the oscillator (128) to the frequency of the modulated signals, - a transmit radio frequency amplifier (124) connected on one side to the output of the transmit radio frequency mixer (123) and on the other side to said transmit-receive antenna (130) and configured to amplify the signal received from the transmit radio frequency mixer (123), - a radio frequency receiving amplifier (125) connected at the input to the transmit-receive antenna (130) and configured to amplify the signal received from the transmit-receive antenna (130), - a radio frequency receiver mixer (126) connected to the output of the radio frequency receiver amplifier (125) and configured to add the predetermined frequency of the oscillator (128) to the frequency of the received signals, - a demodulator (127) connected to the output of the receiving radio frequency mixer (126) and configured to demodulate the signals supplied by the receiving radio frequency mixer (126) and whose output is connected to the communication module (121), - the oscillator (128) being connected to the transmitting radio frequency mixer (123) and to the receiving radio frequency mixer (126).

8. Device (10) according to any one of the preceding claims, the detection block (140) comprises a radio frequency detector mixer (141), a bandpass filter (142), a baseband amplifier (143), a control module (144) and a comparator (145), the radio frequency detector mixer (141) being configured to receive signals from the transmit-receive antenna (130), to subtract their frequency from the predetermined frequency of the oscillator (128) and to transmit the signals of suitable frequency to the bandpass filter (142), the bandpass filter (142) being configured to filter the signal from the radio frequency detector mixer (141) on a predetermined frequency band, the baseband amplifier (143) being configured to amplify the signal filtered by the bandpass filter (142), the control module (144) being configured to control the baseband amplifier (143) and to deliver a threshold voltage signal that can take one or more different values, the comparator (145) being configured to receive on a first input the signal supplied for the baseband amplifier (143) and on a second input the threshold voltage signal supplied by the control module (144),to compare the values ​​of the signal received at the first input and the signal received at the second input, and to provide an output signal representing the difference in voltage values ​​between the two signals.

9. Motor vehicle (1) comprising a device (10) according to any one of the preceding claims.

10. A method for detecting a person (2) in at least one predetermined zone (Z1, Z2) around a motor vehicle (1) according to the preceding claim, said method comprising the steps of: - command (E1), by the electronic control unit (110), of the communication module (121) to transmit signals via the transmit-receive antenna (130), - reception (E7), by the transmitting-receiving antenna (130), of reflected transmitted signals, - subtraction (E16) of the predetermined frequency of the oscillator (128) from the frequency of the received signals, - filtering (E17) of signals within a predetermined detection frequency band, - detection (E20) of the presence of a person in said at least a predetermined area around the vehicle (1) the frequency of the filtered signals is within the predetermined detection frequency band and the amplitude of the filtered signals exceeds a predetermined threshold.

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