Radio frequency module for detecting a user and corresponding detection method

Abstract

The present invention relates to a radio frequency module (1) to be installed on a motor vehicle, comprising: a transmitting and receiving module (10) comprising an antenna (3) for transmitting a pulsed modulated radio frequency signal called a transmission signal (101) and for receiving a reception signal (102) returned to said antenna (3), and a detection circuit (2) for performing at least one frequency demodulation of said reception signal to provide signals I(t) and Q(t) corresponding to in-phase and quadrature components of the frequency demodulated reception signal; a signal extraction module (6) for extracting a first contribution of the frequency demodulated reception signal, said first contribution corresponding to internal reflections of the transmission signal (101) inside the antenna (3); and a first signal processing module (7) for receiving said first contribution and deriving therefrom information relating to the presence of a user by comparison with a predetermined threshold.

Description

Technical Field

[0001] This invention relates to the field of presence detection near motor vehicles.

[0002] The presence detection information is intended for use in controlling a function from outside the vehicle, such as locking and / or unlocking a vehicle access mechanism, or opening and / or closing an access mechanism, or any other function that requires control from outside the vehicle. Background Technology

[0003] In recent years, it has become common to install sensors in the handles of motor vehicles to detect the presence of users' hands, especially in side door handles, front trunk handles, or rear trunk handles.

[0004] These types of presence sensors are typically capacitive, and their limitations are now known. False detections can occur, particularly when the sensor is exposed to water.

[0005] In addition, in the field of vehicle access, radio frequency sensors are known to be designed to locate and / or authenticate users by exchanging data with user terminals, such as vehicle keys or access cards, or smartphones equipped with dedicated applications.

[0006] In summary, radio frequency (RF) signals are electromagnetic signals with a carrier wave, the frequency of which is, for example, between 3 kHz and 300 GHz. In automotive applications, this carrier wave frequency is typically between 5 and 20 GHz.

[0007] Radio frequency (RF) signals can be pulse-modulated, meaning they undergo amplitude modulation to form so-called RF pulses, where the carrier frequency is a pulse within the RF spectrum. This type of signal is particularly useful for determining the distance between a target and a signal transmitting / receiving device.

[0008] Preferably, the pulse-modulated radio frequency signal is a signal modulated according to a modulation technique called "UWB," which is an abbreviation for "Ultra Wide Band." This modulation technique is based on pulses with extremely short transmission durations, preferably shorter than one nanosecond, and is based on a wide frequency spectrum.

[0009] One object of the present invention is to provide a presence detection device and method for detecting the presence of a user in the vicinity of a motor vehicle, and to overcome at least some of the disadvantages of capacitive solutions. Summary of the Invention

[0010] The present invention relates to a radio frequency module intended for installation in a motor vehicle, comprising: A transmit and receive module includes a detection circuit and an antenna configured to transmit a pulse-modulated radio frequency signal, referred to as a transmit signal, and to receive a receive signal returned to the antenna. The detection circuit is configured to perform at least one frequency demodulation on the received signal to provide signals I(t) and Q(t) corresponding to the in-phase and quadrature components of the frequency-demodulated received signal, respectively. The signal extraction module is configured to extract a first contribution of the frequency-demodulated received signal, the first contribution corresponding to the internal reflection of the transmitted signal inside the antenna.

[0011] The radio frequency module also includes a first signal processing module configured to receive the first contribution as input and deduce information related to the presence of the user by comparing the amplitude of the signal associated with the first contribution with a predetermined threshold.

[0012] Specifically, the first signal processing module is configured to receive the first contribution as input, and to derive information related to the presence of a user when at least one predetermined condition is met, wherein the at least one predetermined condition includes the amplitude of the signal corresponding to the first contribution being greater than the predetermined threshold.

[0013] The signal corresponding to the first contribution refers to the first contribution itself, or, where appropriate, the signal obtained after filtering and / or offset compensation of the first contribution.

[0014] The signal extraction module can also extract a second contribution that is different from the first contribution, which is used for at least another application, such as user terminal positioning or gesture detection.

[0015] In use, the detection of user presence is intended to activate a specific function of the vehicle from outside the vehicle, such as locking and / or unlocking of the opening mechanism, opening and / or closing of the opening mechanism, lowering and / or raising of the power window, etc.

[0016] To activate this function, a user places at least a portion of their hand against an outer surface of the vehicle, opposite the antenna. This contact causes a change in the antenna's impedance, which in turn alters the impedance matching between the antenna's impedance and the impedance of the detection circuit connected to the antenna.

[0017] The change in impedance matching causes a change in the amplitude of a portion of the signal received by the detection circuit, corresponding to internal reflections in the antenna. By extracting this portion of the received signal, referred to herein as the first contribution of the received signal, and comparing its amplitude with a predetermined threshold, it is possible to determine whether a hand is touching the antenna.

[0018] Therefore, the present invention enables the use of radio frequency modules as presence sensors in a very simple manner.

[0019] This invention also enables the reuse of devices with radio frequency modules, particularly with UWB modules already present in vehicles for other functions (e.g., for locating or authenticating a user by communicating with a user terminal as described in the introduction, or for detecting gestures by receiving signals reflected from a target moving relative to the vehicle). Specifically, a first contribution of the received signal is used for presence detection, while a second contribution of the received signal can be used for location, authentication, and / or gesture detection.

[0020] According to existing UWB modules, traditional methods cannot detect hand and / or finger pressure on a defined area, while capacitive sensors can. This is due to insufficient resolution in distance measurement (15 cm for a conventional one-nanosecond sampling period) and angle measurement (approximately 5°).

[0021] The present invention proposes a solution based on utilizing a portion of the received signal in a novel manner that is typically sought to be filtered out to escape its influence.

[0022] Advantageously, the present invention therefore proposes to replace the capacitive presence sensor with an ultra-wideband sensor already present in the vehicle, and to modify the ultra-wideband sensor to additionally provide presence detection functionality and form the radio frequency module according to the invention.

[0023] Advantageously, the radio frequency module according to the invention is configured to operate in "radar" mode, in which the received signal includes the reflection of the transmitted signal on the target. As a supplement or variation, the radio frequency module according to the invention is configured to operate in "ranging" mode, in which the received signal includes a signal transmitted by the terminal in response to receiving the transmitted signal.

[0024] Advantageous: The transmitting and receiving modules are configured to transmit a signal consisting of periodic radio frequency pulses, and the received signal consists of a basic received signal corresponding to one of the transmitted radio frequency pulses. The transmitting and receiving modules are also configured to perform time sampling on the received signal or signals I(t) and Q(t) to obtain sampling data I(ti) and Q(ti) related to multiple time windows, the time windows being distributed over multiple time ranges, each time range corresponding to one of the basic received signals, and each time range starting from the transmission time of the corresponding transmitted radio frequency pulse.

[0025] The signal extraction module can be configured to extract the first contribution by selecting a time window of interest and based on the offset between the time window of interest and the starting point of the corresponding time range.

[0026] Particularly advantageously, the signal extraction module is configured to calculate the amplitude of the frequency-demodulated received signal using the sampled data I(ti) and Q(ti), and extract the amplitude value associated with a first sampling window starting from the beginning of each time range.

[0027] Advantageously, the first signal processing module is configured to determine the presence of a user when the amplitude of the signal associated with the first contribution is greater than the predetermined threshold for a duration longer than a predetermined duration threshold.

[0028] The transmitted signal can be an ultra-wideband radio frequency signal.

[0029] In one advantageous implementation: The signal extraction module is further configured to extract a second contribution of the frequency-demodulated received signal, the second contribution corresponding to the reflection of the transmitted signal on a target external to the radio frequency module, or corresponding to a secondary signal radiated by the user terminal in response to receiving the transmitted signal; and The radio frequency module further includes a second signal processing module configured to receive the second contribution as input and thereby derive at least one of the following information: target location, target-executed gesture, or user terminal authentication code.

[0030] Another object of the present invention is a motor vehicle that includes the radio frequency module as described above, wherein the antenna of the module is located in the handle of the opening element of the motor vehicle, or in the structural side pillar of the motor vehicle, particularly in the structural vertical pillar between the front and rear doors, or behind the trim piece located at the front or rear of the vehicle.

[0031] The antenna can be arranged to extend along the outer surface of the vehicle, with the antenna's transmission direction pointing from inside the vehicle to outside.

[0032] Another aspect of the present invention is a presence detection method implemented in a radio frequency module according to the present invention, comprising the following steps: a / Transmits a pulse-modulated radio frequency signal that forms the transmitted signal, and receives a received signal consisting of basic received signals corresponding to one pulse of the transmitted signal. b / The received signal is frequency demodulated to provide signals I(t) and Q(t) corresponding to the in-phase component and quadrature component of the frequency demodulated received signal, respectively; c / Extract a first contribution of the frequency-demodulated received signal, the first contribution corresponding to the internal reflection of the transmitted signal inside the antenna. d / The amplitude of the signal associated with the first contribution is compared with a predetermined threshold (SE), and if the amplitude is greater than the predetermined threshold (SE), the presence of a user is detected.

[0033] Advantageously, when the amplitude is greater than the predetermined threshold and the duration of the state is longer than the predetermined duration threshold, the step of detecting the presence of a user is performed.

[0034] Preferably, the method includes the following steps: The received signal or the signals I(t) and Q(t) are time-sampled to obtain sampling data I(ti) and Q(ti) related to multiple time windows, which are distributed over multiple time ranges, each time range corresponding to one of the basic received signals, and each time range starts from the transmission time of the corresponding transmitted radio frequency pulse; The amplitude of the frequency-demodulated received signal is calculated using the sampled data I(ti) and Q(ti); and For each time range, extract the amplitude value associated with the first sampling window starting from the beginning of that time range. Attached Figure Description

[0035] Other objects, features, and advantages of the invention will become apparent from the following description, which is by way of non-limiting example only and with reference to the accompanying drawings, in which: Figure 1 shows the main components of the radio frequency module according to the present invention. Figure 2 is a graph showing the signal received by the radio frequency module when the user's thumb approaches and then leaves the pressing area opposite the antenna of the radio frequency module three times. Figure 3 is a graph showing the signal from Figure 2 after background noise removal. Figure 4 is a graph showing a portion of the signal shown in Figure 3 that is related to the predetermined sampling window index. Figure 5 is a graph showing the signal in Figure 4 after a low-pass filter has been applied. Figure 6 is a graph showing the results of comparing the signal in Figure 5 with the predetermined threshold, and Figure 7 illustrates the main steps of the detection method according to the present invention. Detailed Implementation

[0036] Figure 1 shows the radio frequency module 1 according to the present invention.

[0037] In use, the radio frequency module 1 is integrated into the vehicle and located at: In the handle of the opening component of the motor vehicle, or In the structural side pillars of the motor vehicle, especially in the structural vertical pillars located between the front and rear doors, or It is located behind the trim piece positioned at the front or rear of the vehicle.

[0038] According to the present invention, the radio frequency module 1 is configured to perform presence detection. When it detects the presence of a user, the radio frequency module 1 generates a presence detection signal and sends it to an auxiliary device configured to activate a given function of the vehicle, particularly the locking and / or unlocking function of a vehicle opening element, or the opening and / or closing function of said opening element, and / or the raising and / or lowering function of the vehicle's power windows.

[0039] Advantageously, in addition to its detection function, the radio frequency module 1 is also used to implement bidirectional communication with the user terminal for authentication or location of the user terminal. This user terminal can be a vehicle key or access card, or a smartphone. As a supplement or variation, the radio frequency module 1 is also used to implement gesture detection to control secondary functions, such as those associated with vehicle entry.

[0040] The radio frequency module 1 includes a transmitting and receiving module 10, also known as a transmitter.

[0041] Transmit and receive module 10 is configured to transmit and receive UWB signals (an abbreviation for "Ultra Wide Band" in English, "ultra large bande" in French).

[0042] The transmitting and receiving module 10 includes a detection circuit 2 and an antenna 3.

[0043] Antenna 3 is configured to perform: Starting from the electrical signal 4 generated at detection circuit 2, an radio frequency transmission signal 101 is emitted, and... The received signal 102 is converted into an electrical signal 5 and guided to the detection circuit 2.

[0044] In Figure 1, for ease of illustration, the received signal 102 is depicted as originating from the external environment of the transmitting and receiving modules. However, as detailed below, the received signal 102 also includes a component corresponding to internal reflections on antenna 3.

[0045] Advantageously, the transmitting and receiving module 10 also includes a matching circuit (not shown) disposed between the antenna 3 and the detection circuit 2. This matching circuit can be formed by a gradual change in the thickness of conductive traces on a printed circuit board carrying the antenna 3 and the detection circuit 2. As a supplement or variation, this matching circuit may include patterns and / or passive resistive, capacitive, and / or inductive elements printed on the printed circuit board.

[0046] Detection circuit 2 is configured to combine a pulse signal with a radio frequency carrier to obtain an electrical signal transmitted to antenna 3, which converts it into an electromagnetic signal to form transmitted signal 101. Detection circuit 2 is also configured to frequency demodulate the electrical signal provided by the antenna and corresponding to received signal 102 to exclude only high-frequency information associated with the carrier. Specifically, detection circuit 2 includes at least a splitter, a phase-shifting element, and two mixers to cause the electrical signal provided by the antenna to interfere with the carrier of transmitted signal 101, thereby providing signals I(t) and Q(t) corresponding to the in-phase and quadrature components of the frequency-demodulated received signal, respectively.

[0047] In use, antenna 3 extends along the outer surface of the vehicle body, inside the vehicle, and extends the detection area to the outside of the vehicle. Preferably, the distance between antenna 3 and the outer surface is less than 5 cm, and more preferably less than 2 cm.

[0048] This invention proposes using antenna 3 to detect the presence of a user's hand and / or fingers in the vicinity of the antenna. When an object is present in the vicinity of antenna 3 or in direct contact with it, the impedance of antenna 3 is disturbed, which affects the impedance matching between antenna 3 and detection circuit 2 and causes changes in the reflection loss at antenna 3.

[0049] These reflection losses correspond to the phenomenon known in English as "spill over," in which a portion of the emitted wave is directly reflected back to antenna 3. More precisely, "spill over" is defined as the portion of the electrical signal that is intended to be converted by antenna 3 into an emitted electromagnetic signal, which is reflected in antenna 3 and converted back into an electrical signal that is considered to originate from the received electromagnetic signal.

[0050] In the conventional design phase of radio frequency (RF) systems, especially ultra-wideband RF systems, "spill over" is typically minimized by maximizing the matching of antenna 3 with respect to detection circuit 2 and / or minimizing reflection loss in antenna 3. The aim is to increase the power of the transmitted signal, and especially to avoid blinding the receiving channel with this spill over, as its amplitude can be much higher than, for example, the amplitude of the useful signal corresponding to the reflection of the transmitted signal at the target. In other words, "spill over" is considered noise and is removed or minimized by optimizing antenna 3 or through digital processing.

[0051] Conversely, in this invention, antenna 3 is advantageously configured to maximize impedance change when a finger approaches. This objective is unusual for antenna design. Furthermore, as detailed below, the signal portion corresponding to spill over is not filtered out or removed in any way upon reception, but rather used to perform presence detection.

[0052] A particularly advantageous embodiment of the invention is described below.

[0053] The transmitted pulse signal 101 consists of a series of periodically transmitted pulses Tx(k). During reception, the received signal 102 is defined as consisting of multiple basic received signals Rx(k), each corresponding to one of the transmitted radio frequency pulses Tx(k). The index k, referred to herein as the first index or CIR index, reflects the position of a transmitted pulse and its corresponding received pulse within the transmitted pulse sequence and the corresponding received pulse sequence, respectively.

[0054] The received signal 102 is frequency demodulated and time-sampled to obtain sampled data I(ti) and Q(ti). Signals I and Q originate from in-phase mixing (signal I) and quadrature-phase mixing (signal Q) respectively between the electrical signal corresponding to the received signal 102 and the carrier wave of the transmitted signal 101. Time sampling can be performed on the received signal 102, or on signals I and Q. Regardless, sampled data I(ti) and Q(ti) are ultimately obtained. Time sampling is performed using an analog-to-digital converter, and its sampling period corresponds to the width of the time window. t.

[0055] Therefore, the sampled data I(ti) and Q(ti) are associated with multiple time windows distributed across different time ranges. Preferably, each time range corresponds to one of the basic received signals Rx(k) and is based on the transmission time of the corresponding transmit pulse Tx(k). For each time range associated with the transmit pulse at index k, successive sampling windows are numbered using a second index i, the value of which reflects the offset relative to the start time of the time range under consideration. Thus, index i represents the gradually increasing delay between the transmission of the transmit pulse Tx(k) at index k and the reception of a portion of the corresponding basic received signal Rx(k). The second index i is also called the "Tap number." It relates to the elapsed time between the transmission of a pulse Tx(k) of the transmit signal and the detection of a portion of the corresponding basic received signal Rx(k).

[0056] The sampling window index i is numbered starting from the transmission time of the corresponding pulse of the transmitted signal, thereby realizing time axis folding (a new time origin is defined each time a new radio frequency pulse Tx(k) is transmitted).

[0057] The amplitude of the frequency-demodulated received signal, corresponding to the modulus of the complex number I + j*Q, is determined and denoted as |CIR|. For each time window ti, the amplitude of the frequency-demodulated received signal, denoted as |CIR|, is determined using the data I(ti) and Q(ti). In other words, for each sampling window of each time range, the CIR signal amplitude ("Channel Impulse Response"), denoted as |CIR|, is determined and calculated using the basic received signal Rx(k) and the transmitted pulse Tx(k).

[0058] Typically, the amplitude of the frequency-demodulated received signal is represented in the form of a graph as shown in Figure 2, where: The first horizontal axis reflects the first index k or CIR index, which identifies a given pulse k of the transmitted signal; The second horizontal axis reflects the second index i of the time sampling window and represents the time offset, or time t, between the transmission of the transmitted signal pulse Tx(k) and the reception of a portion of the corresponding basic received signal Rx(k); and The vertical axis reflects the amplitude of the received signal after frequency demodulation, denoted as |CIR|.

[0059] In use, when a part of the hand is located in close proximity to antenna 3 (in practice, the distance between antenna 3 and the part of the hand is less than 5 cm), a matching change of antenna 3 will occur, which will translate into an amplitude change of "spill over".

[0060] For each basic received signal Rx(k), the “spill over” or internal reflection in antenna 3 will affect the amplitude of the corresponding frequency-demodulated received signal at the first sampling window (index i=i0) counting from the transmission of the corresponding pulse Tx(k) of the transmitted signal. This amplitude variation is used as a characteristic of the user’s presence, especially the presence of a hand and / or finger near antenna 3.

[0061] Figure 2 illustrates the case where the user's thumb approaches the device three times consecutively, which translates to three changes in the amplitude (|CIR|) of the received signal at i=i0 after frequency demodulation.

[0062] Figures 3 through 6 illustrate the different stages of processing the amplitude (|CIR|) of the frequency-demodulated received signal for performing presence detection.

[0063] First, the signal |CIR| in Figure 2 is processed to remove background noise, retaining only the dynamic portion of the signal corresponding to the three thumb-pressing effects. The resulting signal is shown in Figure 3.

[0064] The second step is to extract the signal associated with the predetermined value second index SI from the signal in Figure 3, where SI = i0, which is the index of the first sampling window as defined above.

[0065] In other words, the first contribution corresponding to the internal reflection of the transmitted signal (101) inside the antenna (3) is extracted from the frequency-demodulated received signal.

[0066] The resulting signal is shown in Figure 4. It corresponds to the cross-sectional view of Figure 3 at the plane where i=i0.

[0067] The extracted signal, or first contribution, is then smoothed using a low-pass filter. The low-pass filter advantageously has a cutoff frequency fc = 10 Hz. An offset (constant) can also be removed to eliminate any environmentally relevant contributions. The resulting signal is shown in Figure [Fig 5]. This is the signal related to the first contribution, here corresponding to the first contribution filtered and offset by a constant amplitude.

[0068] Then, the amplitude of the signal is compared with a predetermined threshold SE. If the amplitude is greater than the threshold SE, it is considered that a user is detected. Otherwise, it is considered that no user is detected. This comparison step can correspond to forming a signal as shown in Figure 6, taking a first value (high value here) when the amplitude is greater than the threshold SE, and taking a second value (low value here) when the amplitude is less than or equal to the threshold SE. In other words, information related to the presence of a user is determined by comparing the amplitude of the signal related to the first contribution with the predetermined threshold SE.

[0069] In various variations, the signal associated with the first contribution corresponds only to the filtered first contribution without constant amplitude offset. In other variations, the signal associated with the first contribution corresponds directly to the first contribution (without filtering or constant amplitude offset).

[0070] The three thumb presses shown in Figure 2 reappear in Figure 6.

[0071] Referring again to Figure 1, the radio frequency module 1 to be installed in a motor vehicle includes the transmitting and receiving module 10 as described above, and a signal extraction module 6 connected at its input to the transmitting and receiving module 10 and at its output to the first signal processing module 7. Here, but not limited to, the signal extraction module 6 is also connected at its output to a second signal processing module 8.

[0072] The signal extraction module 6 is configured to extract the first contribution from the signal obtained by means of the received signal 102, the first contribution corresponding to the internal reflection of the transmitted signal 101 in the antenna 3.

[0073] Here, and advantageously, the signal extraction module 6 is also configured to extract a second contribution from the signal obtained by means of the received signal 102, which is different from the first contribution. This second contribution corresponds to the remainder of the received signal and may correspond to the reflection of the transmitted signal on a distant object or to a new signal transmitted by the user terminal in response to receiving the transmitted signal.

[0074] The second signal processing module 8 is configured to receive the second contribution as input and thereby derive terminal location information, terminal authentication information, or user gesture recognition information. A vehicle access management system (not shown) can receive this information and responsively control at least one vehicle access function, particularly the locking or unlocking of an access device, or the opening or closing of the access device.

[0075] The first signal processing module 7 is configured to determine the presence of a user in the vicinity of the vehicle by means of the first contribution extracted by the signal extraction module 6 as detailed above.

[0076] Advantageously, the first signal processing module 7 is connected to a management system that uses the presence information provided by the first signal processing module 7 to control at least one vehicle function, in particular the locking and / or unlocking of an opening element, or the opening and / or closing of the opening element, or the lowering and / or raising of a power window.

[0077] The present invention also covers a motor vehicle having at least one opening element such as a door and having the radio frequency module 1 as described above.

[0078] Radio frequency module 1 is configured to perform the detection method described below. This detection method, as shown in Figure [Fig 7], includes the following steps: Step E1 (implemented by the transmitting and receiving module 10): transmitting a transmission signal (101) and receiving a corresponding reception signal (102). Step E2 (implemented by the detection circuit 2 of the transmitting and receiving module 10): The received signal is frequency demodulated to provide signals I(t) and Q(t) as described above, which correspond to the in-phase component and quadrature component of the frequency demodulated received signal, respectively. Step E3 (implemented at least in part by extraction module 6, and also in part by detection circuit 2 where appropriate): Extract the first contribution of the frequency-demodulated received signal, the first contribution corresponding to the internal reflection of the transmitted signal (101) inside the antenna (3), Step E4 (implemented by the first signal processing module 7): The amplitude of the signal related to the first contribution is compared with a predetermined threshold SE. If the amplitude of the signal is greater than the predetermined threshold SE, it is considered that a user is detected in the vicinity of the vehicle. If not, it is considered that the user is not in the vicinity of the vehicle.

[0079] Preferably, and as detailed above, the method includes time sampling (performed on the received signal or signals I and Q) to obtain sampled data I(ti) and Q(ti) as described above. The sampled data I(ti) and Q(ti) are associated with multiple time windows. These time windows are distributed across multiple time ranges, each corresponding to one of the basic received signals Rx(k) constituting the received signal. Each time window begins at the transmission time of the corresponding pulse Tx(k) of the transmitted signal 101. This sampling is advantageously performed in step E2 of the received signal frequency demodulation.

[0080] Preferably, and as detailed above, the method includes calculating the amplitude of the demodulated received signal using the sampled data I(ti) and Q(ti). Advantageously, this amplitude is denoted as |CIR| and is equal to the modulus of the complex number I+j*Q. This amplitude calculation may form part of step E3 or E2.

[0081] Step E3, which extracts the first contribution, is then composed of extracting the amplitude value |CIR|. For each time range, the extracted amplitude value is related to the first sampling window starting from the beginning of that time range.

[0082] The method advantageously includes a step of shaping the signal constituting the first contribution to obtain a smoothed and calibrated signal, the amplitude of which is compared with a predetermined threshold SE in step 4. These shaping steps may include low-pass filtering operations and constant (offset) subtraction, as described with reference to Figures 2 to 5. When these steps are present, they are performed by the signal extraction module 6 and / or the first signal processing module 7.

[0083] These signal shaping steps may also include subtracting an offset value, determined based on the average and standard deviation of the signal values ​​over the considered sampling window and the previous pulse k. When the standard deviation becomes greater than a predetermined threshold, the offset value is updated with the average of the signal values ​​over the considered sampling window and the previous pulse k. Alternatively, high-pass filtering is performed.

[0084] The method can be refined by applying a minimum duration within which the obtained amplitude is greater than a threshold SE. In one particular implementation, when it is determined that the obtained amplitude is greater than a predetermined threshold SE, it is determined whether the obtained amplitude remains greater than the predetermined threshold for a period of time at least equal to the predetermined duration threshold. If so, presence is detected. If not, presence is not detected.

Claims

1. A radio frequency module (1) intended to be installed in a motor vehicle, comprising: The transmitting and receiving module (10) includes a detection circuit (2) and an antenna (3) configured to transmit a pulse-modulated radio frequency signal called a transmit signal (101), which consists of periodic radio frequency pulses, and to receive a receive signal (102) returned to the antenna (3), which consists of a basic receive signal corresponding to one of the transmitted radio frequency pulses. The transmitting and receiving module (10) is further configured to time sample the received signal (102) or signals I(t) and Q(t) to obtain sampled data I(ti) and Q(ti) related to multiple time windows, the time windows being distributed over multiple time ranges, each time range corresponding to one of the basic received signals, and each time range starting from the transmission time of the corresponding transmitted radio frequency pulse, and the detection circuit (2) is configured to perform at least one frequency demodulation on the received signal to provide signals I(t) and Q(t) corresponding to the in-phase component and quadrature component of the frequency demodulated received signal, respectively; The signal extraction module (6) is configured to extract a first contribution from the frequency-demodulated received signal by selecting a time window of interest and based on the offset between the time window of interest and the starting point of the corresponding time range, the first contribution corresponding to the internal reflection of the transmitted signal (101) inside the antenna (3). It also includes a first signal processing module (7), configured to receive the first contribution as input and derive information related to the presence of the user by comparing the amplitude of the signal associated with the first contribution with a predetermined threshold (SE), characterized in that the signal extraction module (6) of the radio frequency module is configured to calculate the amplitude of the frequency-demodulated received signal using the sampled data I(ti) and Q(ti), and extract the amplitude value associated with a first sampling window starting from the start of the time range for each time range.

2. The radio frequency module (1) according to the preceding claim, characterized in that, The first signal processing module (7) is configured to determine the presence of a user when the amplitude of the signal associated with the first contribution is greater than a predetermined threshold (SE) for a duration longer than a predetermined duration threshold.

3. The radio frequency module (1) according to any one of claims 1 to 2, wherein, The transmitted signal (101) is an ultra-wideband radio frequency signal.

4. The radio frequency module (1) according to any one of claims 1 to 3, characterized in that: The signal extraction module (6) is further configured to extract a second contribution of the frequency-demodulated received signal, the second contribution corresponding to the reflection of the transmitted signal (101) on a target outside the radio frequency module (1), or corresponding to a secondary signal radiated by the user terminal in response to receiving the transmitted signal (101); and The radio frequency module (1) further includes a second signal processing module (8) configured to receive the second contribution as input and thereby derive at least one of the following information: target location, target-executed gesture, or user terminal authentication code.

5. A motor vehicle comprising a radio frequency module according to any of the preceding claims, wherein the antenna (3) of the module is located in the handle of the opening element of the motor vehicle, or in the structural side pillar of the motor vehicle, particularly in the structural vertical pillar between the front side door and the rear side door, or behind a decorative element disposed at the front or rear of the vehicle.

6. The motor vehicle according to claim 5, wherein, The antenna (3) is arranged to extend along the outer surface of the motor vehicle, and the transmission direction of the antenna (3) is from inside the vehicle to outside the vehicle.

7. A presence detection method implemented in the radio frequency module (1) according to any one of claims 1 to 6, comprising the following steps: Transmit a pulse-modulated radio frequency signal that forms the transmitted signal (101), and receive a received signal (102) consisting of a basic received signal corresponding to a pulse of the transmitted signal (101), respectively; demodulate the received signal to provide signals I(t) and Q(t) corresponding to the in-phase component and quadrature component of the frequency-demodulated received signal, respectively; extract a first contribution of the frequency-demodulated received signal, the first contribution corresponding to the internal reflection of the transmitted signal (101) inside the antenna (3), compare the amplitude of the signal related to the first contribution with a predetermined threshold (SE), and if the amplitude is greater than the predetermined threshold (SE), detect the presence of a user.

8. The detection method according to claim 7, wherein, When the amplitude is greater than the predetermined threshold (SE) and the duration of the state is longer than the predetermined duration threshold, the step of detecting the presence of a user is performed.

9. The detection method according to any one of claims 7 or 8, wherein: The received signal (102) or the signals I(t) and Q(t) are time-sampled to obtain sampling data I(ti) and Q(ti) related to multiple time windows, which are distributed over multiple time ranges, each time range corresponding to one of the basic received signals, and each time range is started from the transmission time of the corresponding transmitted radio frequency pulse; The amplitude of the frequency-demodulated received signal is calculated using the sampled data I(ti) and Q(ti); as well as For each time range, extract the amplitude value associated with the first sampling window starting from the beginning of that time range.

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