Detection and / or communication system for motor vehicle comprising module for emitting light beam and module for receiving light beam

Abstract

The invention relates to a system (1) comprising: a transmitting module (2) comprising: a light emitting module (21) capable of emitting a light beam (F1), the spectrum of which has at least a portion in the visible spectrum; and a linear polarizer means (25) arranged to polarize said emitted light beam in a given polarization direction (P); a receiving module (3) capable of receiving the light beam (F2), where the receiving module comprises a basic acquisition module (32) comprising a photodetector (32a) capable of converting its received light signal into an electrical signal, characterized in that the receiving module comprises a linear polarizer filter (34) capable of filtering the light beam (F2), the linear polarizer filter is arranged to transmit only a component of the received light beam polarized in the given polarization direction to the base acquisition module.

Description

[0001] The present invention relates to the field of automotive lighting functions and data transmission functions using light emitted by automotive lighting systems. More specifically, the present invention relates to a system for a motor vehicle for receiving data transmitted by a light beam.

[0002] In the automotive field, it is known to use the light beam emitted by a lighting module both to perform a given photometric function and to transmit data.

[0003] Conventionally, the light source used to emit this light beam is controlled by a pulse width modulated (PWM) electrical signal. Thus, this PWM signal periodically activates and deactivates the light source, so that the emitted light beam consists of continuous light pulses with a sufficiently high frequency that the human eye can no longer distinguish them. The intensity of the emitted light beam depends on the duty cycle of this PWM signal, making it possible to control the intensity by adjusting this duty cycle. This PWM signal can then be modulated with a data sequence so that this data sequence is transmitted by the light beam. In this way, the light beam can maintain its original function, i.e., perform a photometric function while allowing the transmission of a data sequence. This type of technology is, for example, called visible light communication (VLC) or also light fidelity (LiFi).

[0004] Thus, in addition to performing one or more photometric functions, such as daytime running lights or low beam lighting, various functions can be implemented by means of a lighting module of this type. For example, a lighting module can thus be integrated into a transmitting module capable of performing a function involving the communication of a data sequence with another vehicle or with a piece of infrastructure equipped with a receiving module capable of demodulating the received light beam in order to extract the data sequence therefrom. In another example, a headlight comprising a transmitting module can be equipped with a receiving module in order to receive the emitted light beam (after it has been reflected on an object in the vicinity of the vehicle). The time of flight of the emitted light beam can then be determined by demodulating and extracting the transmitted data sequence, and thus the distance separating the vehicle from the object can be assessed.

[0005] However, this type of system based on the use of a transmitting module capable of performing both a photometric light function and a data transmission function has disadvantages. In fact, the receiving module intended to receive the light beam conveying the data (whether it is arranged in the same vehicle or in another vehicle) must include at least one photodetector for converting this light beam into an electrical signal in order to demodulate this signal and extract the data sequence therefrom.

[0006] However, under certain conditions, the signal-to-noise ratio of this photodetector may degrade significantly. This is particularly true under full sunlight conditions. In fact, under such conditions, the light from the sun in the visible spectrum in which the light source of the transmitting module operates may be significantly greater than the light from the received light beam, saturating the photodetector. In this state, the photodetector enters a nonlinear operating state and cannot adequately convert the light beam into an electrical signal that can be demodulated without losing information.

[0007] Therefore, there is a need for a system capable of transmitting a data sequence from a transmitting module (which incorporates a lighting module involved in performing a photometric function) to an acquiring module, wherein the signal-to-noise ratio is optimal in all weather conditions, including full sunlight.

[0008] The present invention falls within this background and is intended to meet this need.

[0009] To this end, the object of the invention is a system for a motor vehicle, comprising:

[0010] a. an emission module, the emission module comprising: a light emitting module capable of emitting a light beam, the spectrum of which has at least a portion in the visible spectrum; and a linear polarizer device arranged to polarize the emitted light beam in a given polarization direction;

[0011] b. A receiving module capable of receiving a light beam, wherein the receiving module comprises a basic acquisition module, the basic acquisition module comprises a photodetector capable of converting the received light signal into an electrical signal, and characterized in that the receiving module comprises a linear polarizer filter, which is arranged to transmit only the component of the received light beam polarized in the given polarization direction to the basic acquisition module.

[0012] As indicated above, in full sunlight conditions, sunlight is added to the light emitted by the transmitting module, which may saturate one or more photodetectors of the receiving module. However, sunlight is generally unpolarized or barely polarized. In other words, half of this light is polarized in polarization direction P, and the other half of this light is polarized in another polarization direction S.

[0013] Furthermore, linearly polarized light retains its specular polarization after reflection on a surface. However, the different use cases considered by the invention target either the emission without reflection of light (in the case of a communication function) or the specular reflection on a surface of an object to be detected.

[0014] It will therefore be understood that the light beam received by the receiving module is composed of light polarized in said polarization direction provided by the linear polarizer device and, in the case of sufficient sunlight, unpolarized light. The linear polarizer filter then allows the removal of the component of polarized sunlight in the other polarization direction, so that the amount of sunlight reaching the photodetector is divided by two. Thus, saturation of the photodetector or photodetectors of the receiving module is avoided in the case of sufficient sunlight, and the signal-to-noise ratio is therefore multiplied by two.

[0015] In one embodiment of the invention, the light module is capable of emitting a light beam whose spectrum has a peak at a wavelength in the visible light domain, in particular between 400 nm and 500 nm. Advantageously, the light module comprises a light source comprising a semiconductor generator capable of emitting a primary light beam, in particular a primary light beam whose spectrum has a peak at a wavelength in the visible light domain, and a photoluminescent element capable of converting said primary light beam in order to obtain said light beam.

[0016] The semiconductor may be made, for example, of gallium nitride or even GaN, capable of emitting blue light by electroluminescence and in response to an electric current passing through it. The photoluminescent element may be, for example, in the form of a resin comprising cerium-doped yttrium aluminum garnet (CE:YAG), capable of absorbing blue light and emitting yellow light by photoluminescence and in response to excitation by this light. The photoluminescent element is arranged on the generator in such a way that a portion of the blue light excites this element, causing it to emit yellow light by photoluminescence. Another portion of the blue light passes through this element. Thus, when the light source is powered, it emits blue and yellow light simultaneously, the light thus formed appearing white to the human eye.

[0017] Thus, the light source may be a laser source, a light emitting diode, a vertical cavity surface emitting laser (VCSEL) or even a super luminescent diode (SLED).

[0018] Advantageously, the lighting module may comprise an optical unit arranged to project the light emitted by the light source in order to form said light beam. It may be provided that the linear polarizer device is arranged between the light source and the optical unit or downstream of said optical unit.

[0019] In one embodiment of the invention, the linear polarizer arrangement comprises a semi-reflective plate arranged downstream of the light emitting module and tilted at a Brewster's angle with respect to the emission axis of said light emitting module.

[0020] In another embodiment of the invention, the linear polarizer arrangement comprises a grid polarizer.

[0021] If desired, the linear polarizer device may comprise: a linear polarizer arranged to transmit a portion of the emitted light beam by polarizing the portion in the given polarization direction, and to reflect another portion of the emitted light beam by polarizing the other portion in another polarization direction; and an optical delay element arranged to receive the other portion and polarize the other portion in the given polarization direction. An optical delay element is understood to mean an optical element capable of introducing a phase delay, and in this case a 180° phase delay, between the P and S components of the light, thereby changing the polarization direction of the linearly polarized light. Thus, substantially all of the light emitted by the light-emitting module can be polarized using the same component and thus the yield of the linear polarizer device is maximized.

[0022] In this example, the linear polarizer may be a semi-reflective plate or a grid polarizer tilted at a Brewster angle relative to the emission axis of the light emitting module. The optical delay element may be, for example, a half-wave plate or even a pair of Fresnel rhombus prisms. If applicable, the linear polarizer arrangement may include at least one optical bypass element, such as a plane mirror, arranged downstream of the linear polarizer or between the linear polarizer and the optical delay element or downstream of the optical delay element, such that the portion of the light beam emitted by the linear polarizer and the portion polarized by the optical delay element are emitted in the same direction.

[0023] Preferably, the first linear polariser arrangement is arranged to polarise said emitted light beam in a polarisation direction P.

[0024] In practice, it has been found that under certain conditions, sunlight can be polarized in polarization direction S. This is the case, for example, when the sun is low at dawn or dusk and its light is reflected by a reflective surface inclined at Brewster's angle, such as a pool of water. Therefore, under these conditions, it is advantageous to favor the polarization of the emitted light beam in polarization direction P in order to avoid saturation of the photodetector.

[0025] Advantageously, provision can be made that the linear polarizer filter comprises a linear polarizer, such as a semi-reflective plate or a grid polarizer tilted at the Brewster angle relative to the optical axis of the receiving module, said linear polarizer being arranged upstream of the elementary acquisition module.

[0026] In one embodiment of the present invention, the receiving module includes a plurality of basic acquisition modules, each of which includes a photodetector capable of converting the received optical signal into an electrical signal.

[0027] For example, the group of photodetectors may form a sensor, such as a single electronic component.

[0028] Advantageously, the photodetector of the or each elementary acquisition module is an avalanche photodiode. This type of photodetector is also known as a single photon avalanche diode (SPAD). Thus, the group of avalanche photodiodes can form a silicon photomultiplier (SiPM). This type of photodetector can detect light with a high gain (e.g. 10 6 The invention can reduce the incidence of a single photon (a gain of the order of magnitude) and thus compensate for the degradation of the signal-to-noise ratio due to external conditions or even due to absorption by the filter.

[0029] According to one embodiment of the invention, the receiving module may comprise an optical unit arranged in front of the basic acquisition module. It may be provided that the linear polarizer filter is arranged between the basic acquisition module and the optical unit or upstream of said optical unit.

[0030] In one embodiment of the present invention, the transmitting module includes a modulation unit, which is capable of receiving a data sequence and is arranged to modulate the emitted light beam from the received data sequence, and the receiving module includes a demodulation unit, which is connected to the photodetector and is arranged to extract the data sequence from the electrical signal converted by the photodetector.

[0031] Advantageously, the modulation unit is arranged to generate a pulse width modulated control signal, modulate the control signal using the received data sequence, and control the emission of the light beam by the light module from the modulated control signal. For example, the modulation unit may be arranged to convert the received data sequence into a modulation signal and modulate the control signal with this modulation signal, e.g. in terms of amplitude, frequency or phase.

[0032] Where appropriate, the modulation unit may be arranged to control the light source, and in particular to control the supply of electrical power to this light source, in order to modulate the light beam.

[0033] Advantageously, the system comprises a computing unit arranged to detect the presence of a data sequence modulating the light beam emitted by the transmitting module in a data sequence extracted by the demodulation unit from an electrical signal converted by the photodetector from the light beam received by the receiving module, and to determine the flight time separating the emission of the emitted light beam and the reception of the received light beam.

[0034] Advantageously, the emission module is arranged so that the light beam fully or partially participates in the fulfillment of a predetermined legal photometric function. For example, it may be a daytime running light (DRL) which has the advantage of emitting at low intensity over a wide field.

[0035] Advantageously, the receiving module and the transmitting module are arranged in a headlight of a motor vehicle.

[0036] Another object of the invention is a motor vehicle headlight comprising a receiving module and a transmitting module of the system according to the invention.

[0037] The present invention will now be described using examples, which are for illustration purposes only and in no way limit the scope of the invention, and with reference to the accompanying drawings, in which the various figures show:

[0038] [ Figure 1 ] schematically and partially shows a view of a system of a motor vehicle according to one embodiment of the present invention;

[0039] [ Figure 2 ] schematically and partially shows [ Figure 1 ] is an embodiment of a linear polarizer device for a system in.

[0040] Throughout the following description, elements that are identical in structure or function and appear in the various figures are given the same reference numerals unless otherwise specified.

[0041] [ Figure 1 ] shows a system 1 for a motor vehicle according to an embodiment of the present invention.

[0042] The system 1 comprises a transmitting module 2 arranged to transmit a light beam F1 and a receiving module 3 intended to receive a light beam F2.

[0043] In the example described, the transmitting module 2 and the receiving module 3 are arranged in the same headlight of the motor vehicle. Provision can be made, without departing from the scope of the invention, for the modules 2 and 3 to be arranged at different locations in the motor vehicle.

[0044] The transmitting module 2 includes a light emitting module 21 and a modulation unit 22 .

[0045] The light module 2 is arranged so that the light beam F1 emitted by it has an electromagnetic spectrum S, at least a part of which is in the visible spectrum. Figure 1 ], the spectrum S has a blue intensity peak P1 or light at 450nm. It should be noted that the spectrum S has other intensity peaks in the visible light domain and / or infrared domain.

[0046] In order to emit this light beam F1, the light emitting module 21 comprises a light source 23 capable of emitting light and an optical unit 24 arranged to project these light rays so as to form the light beam F1. In the present invention, the optical unit 24 may also comprise one or more reflectors, one or more lenses, one or more apertures, or one or more collimators, or even a combination of several of these optical elements.

[0047] The light source 23 comprises, for example, a semiconductor generator (not shown), such as gallium nitride or even GaN, capable of emitting blue light having an emission peak at 450 nm by electroluminescence and in response to a current passing through the generator. The light source also comprises a photoluminescent element in the form of a resin comprising cerium-doped yttrium aluminum garnet (CE:YAG), capable of absorbing blue light and emitting yellow light by photoluminescence and in response to excitation by the light.

[0048] The photoluminescent element is arranged on the generator in such a way that a part of the blue light excites the element, causing it to emit yellow light by photoluminescence. Another part of the blue light passes through the element. Therefore, when the light source 23 is powered, it emits blue and yellow light at the same time, and the light thus formed appears white to the human eye.

[0049] In the case where the light beam F1 consists partly or completely of white light, this light beam F1 can be used to partly or completely participate in the fulfillment of a predetermined photometric function, in particular a legal function. In this case, the optical unit 24 is arranged to shape this light beam F1 so that its photometric distribution meets the requirements of the function. For example, it can be provided that the light beam F1 participates in the fulfillment of a daytime running light (DRL) function.

[0050] In addition to this photometric function, the light beam F1 allows the system 1 to perform functions of detecting and evaluating the position of obstacles on the road and / or communicating with another vehicle or with a piece of road infrastructure.

[0051] The modulation unit 22 is capable of receiving a data sequence, for example a predetermined sequence in the case where it is used for detecting and evaluating the position of obstacles, in which case the sequence is stored in a memory of the system 1 (not shown) or, as a variant, is generated by a computer of the system 1 (not shown) for communication with a data sequence provided in another vehicle or in a piece of road infrastructure. Figure 1 ] to communicate with the same system in the system.

[0052] The modulation unit 22 is arranged to use this data sequence to modulate the light beam F1 emitted by the light emitting module 21 , for example by controlling the supply of electrical power to the light source 23 .

[0053] For these purposes, the modulation unit 22 comprises a pulse width modulated control signal generator. This control signal is used to control a switch mode power supply (not shown) to the light source 23. Conventionally, the duty cycle of this control signal set by the modulation unit 22 is therefore used to control the average electrical power supplied to the light source 23, and therefore to control the luminous intensity of the light beam F1, so as to meet the requirements of the photometric function it performs.

[0054] In the example described, the modulation unit 22 is arranged to convert the data sequence into a modulation signal and to modulate the initial control signal using this modulation signal. It should be noted that several types of modulation may likewise be employed within the scope of the invention, and in particular on-off keying (OOK) modulation, pulse code modulation (PCM), pulse amplitude modulation (PAM), pulse width modulation (PWM), or even pulse position modulation (PPM).

[0055] When using the detection and evaluation of the position of obstacles, it can be provided that the data sequence is a binary signal and / or Hamming weights exhibiting different predetermined characteristics (in particular such as autocorrelation peaks of zero time shift and / or non-zero time shift and / or low autocorrelation values ​​of significant length, wherein these characteristics allow improving the signal-to-noise ratio of the system) so that the average light intensity level of the emitted light beam remains substantially unchanged during its modulation with the data sequence. Such a sequence can be generated, for example, with the aid of a random code or pseudo-random code generation algorithm.

[0056] The emitted light beam F1 is thus composed of a series of continuous light pulses with a sufficiently high frequency (e.g. greater than 30 MHz, in particular ranging between 50 MHz and 100 MHz) so that the human eye can no longer distinguish them. In addition, the amplitude, width and / or position of each pulse relative to the period allow the light beam F1 to transmit a data sequence to the receiving module 3.

[0057] The receiving module 3 comprises an optical unit 31 , downstream of which a plurality of basic acquisition modules 32 are arranged. The receiving module 3 further comprises a demodulation unit 33 .

[0058] Each of the elementary acquisition modules 32 comprises a photodetector 32a. Therefore, the light beam F2 received by the receiving module 3 is focused by the optical unit 31 on one or more of the photodetectors 32a.

[0059] Light beam F2 may be light beam F1 likewise emitted by transmitting module 2 and reflected by an obstacle or object in the vehicle's environment towards receiving module 3 , or a light beam emitted by a transmitting module of another vehicle's system or a piece of road infrastructure equipped with a transmitting module similar to module 2 .

[0060] The photodetectors 32a are identical and are each formed by an avalanche photodiode of a silicon photomultiplier. These photodiodes are distributed in an array. It should be noted that the dimensions of the photodetectors 32a are in the micrometer range. Thus, due to the use of avalanche photodiodes, the assembly forms a sensor with a receiving spatial resolution of the order of 0.1° and a particularly high detection capability even under degraded acquisition conditions.

[0061] Each of the photodetectors converts the portion of the light beam F2 that it receives into an electrical signal that it transmits to a demodulation unit 33 which can then extract the data sequence therefrom.

[0062] In the case where the system 1 implements a communication function, this data sequence can then be transmitted to the vehicle's computer in order to be interpreted, decoded and / or transmitted to equipment or a user of the vehicle.

[0063] In the case where the system 1 implements a function of detecting and evaluating the position of an object or an obstacle, this data sequence can be transmitted to the calculation unit 4 of the system 1. Thus, this calculation unit 4 can detect therein the presence of the predetermined data sequence with which the modulation unit 22 has modulated the light beam F1 emitted by the light module 21. In this case, the calculation unit can determine the flight time between the emission of the light beam F1 and the reception of the light beam F2.

[0064] When the sunlight conditions in the vicinity of the vehicle are particularly bright, sunlight is therefore added to the light beam F2 received by the receiving module 3. The light from the sun in the visible spectrum is much brighter than the light from photometric functions such as daytime running lights.

[0065] Therefore, the light beam F2 received by the receiving module 3 is first composed of the light beam F1 emitted by the transmitting module 2 or by another similar transmitting module and sunlight. For the wavelength range in the visible light domain, the intensity level of this light beam F2 far exceeds the intensity level of the light beam F1.

[0066] In order to avoid saturation of the photodetector 32 a , the transmission module 2 comprises a linear polarizer device 25 .

[0067] In the example described, the linear polarizer device 25 is arranged between the light source 23 and the optical unit 24. It may be provided that this device 25 is arranged at another location of the emission module, such as downstream of the optical unit 24, without departing from the scope of the present invention.

[0068] This linear polariser means 25 is arranged to polarise the light of the beam F1 in a preferred polarisation direction, ie direction P.

[0069] [ Figure 2 ] shows a linear polarizer device 25 according to an embodiment of the present invention.

[0070] The device 25 comprises a linear polarizer 25a, which is made in the form of a semi-reflective plate, arranged upstream of the light source 23 and inclined at the Brewster angle relative to the emission axis of this light source 23. Therefore, the linear polarizer 25a is able to emit a part of the light emitted by the light source 23 by polarizing this part in the polarization direction P, and reflect another part of this light by polarizing this other part in the polarization direction S.

[0071] The plane mirror 25b is arranged downstream of the light reflected by the plate 25a so as to reflect this light in the same direction as the light transmitted by the plate 25a.

[0072] Half-wave plate 25c is arranged downstream of plane mirror 25b. This half-wave plate 25c can introduce 180° phase delay between P and S components of light. In the case where the light reflected by plane mirror 25b is generally polarized in direction S, the light is therefore polarized in direction P at the output of half-wave plate 25c.

[0073] Therefore, it should be understood that Figure 2 ]The device 25 described allows substantially all light emitted by the light source 23 to be polarized in direction P.

[0074] Other embodiments of the device 25 can be designed, for example, by using other optical components such as grid polarizers or Fresnel rhombus prisms. A single linear polarizer can also be used to simplify the design of the device 25. The device 25 can also be designed to polarize the light from the light source 25 in the direction S instead of the direction P.

[0075] like[ Figure 1 ], the light of the beam F1 is therefore substantially polarized in the polarization direction P. Therefore, when this beam F1 is reflected by an obstacle with specular reflection, the beam retains its polarization. In other words, the component of the beam F2 received by the receiving module 3 that corresponds to the beam F1 emitted by the transmitting module 2 or by another similar transmitting module is polarized in the direction P.

[0076] However, sunlight is usually unpolarized or barely polarized. In other words, half of the component of the light beam F2 corresponding to sunlight is polarized in polarization direction P, and the other half is polarized in another polarization direction S.

[0077] Therefore, the receiving module 3 comprises a linear polarizer filter 34. In the example described, the linear polarizer filter 34 is arranged between the optical unit 31 and the basic acquisition module 32. It can be provided that this device 25 is arranged at another location of the receiving module, such as upstream of the optical unit 31, without departing from the scope of the invention.

[0078] The filter 34 is arranged to transmit to the elementary acquisition module 32 only the component of said light beam F2 polarized in the same polarization direction as that of the light beam F1 .

[0079] It may be provided that the linear polarizer filter 34 comprises a linear polarizer, such as a semi-reflective plate or a grid polarizer tilted at the Brewster angle relative to the optical axis of the optical unit 31 .

[0080] It will therefore be understood that the filter 34 allows eliminating the component of the beam F2 polarized in the direction S, which is due only to the sun. In this way, the photodetectors receive only half of the sun's light, so that saturation of these photodetectors 32a is thus avoided.

[0081] The above description clearly explains how the invention achieves the objectives it sets, namely to provide a system for a motor vehicle capable of performing communication or detection functions from visible light and whose signal-to-noise ratio is optimal, whatever the weather conditions, including in case of full sunlight. These objectives are achieved in particular using a transmitting module and a receiving module each equipped with polarizer means. These means allow a significant reduction in the signal-to-noise ratio associated with the sun, taking into account the fact that sunlight is not polarized.

[0082] In any case, the invention is not limited to the embodiments specifically described in this document and extends in particular to all equivalent devices and to any technically operable combination of these devices. In particular, other types of light sources than those described may be used, such as laser diodes, VCSELs or SLEDs. Photometric functions other than those described may also be performed, in particular low-beam lighting functions or position light signaling functions. Other configurations of linear polarizer devices and / or linear polarizer filters may also be provided.

Claims

1. A system (1) for a motor vehicle, the system comprising: a. an emission module (2), the emission module comprising: a light emitting module (21), the light emitting module being capable of emitting a light beam (F1), the spectrum of which at least partly lies in the visible spectrum; and a linear polarizer device (25), the linear polarizer device being arranged to polarize the emitted light beam in a given polarization direction (P); b. A receiving module (3), which is capable of receiving a light beam (F2), wherein the receiving module comprises a basic acquisition module (32), the basic acquisition module comprises a photodetector (32a) capable of converting the light signal it receives into an electrical signal, and characterized in that the receiving module comprises a linear polarizer filter (34), which is arranged to transmit only the component of the received light beam polarized in the given polarization direction to the basic acquisition module.

2. System (1) according to the preceding claim, characterized in that The linear polarizer device (25) comprises a semi-reflective plate (25a) which is arranged downstream of the light emitting module (21) and is inclined at a Brewster angle relative to the emission axis of the light emitting module.

3. A system (1) according to any one of the preceding claims, characterised in that The linear polarizer arrangement (25) comprises a grid polarizer.

4. A system (1) according to any one of the preceding claims, characterised in that The linear polarizer device (25) comprises: a linear polarizer (25a), which is arranged to transmit a part of the emitted light beam (F1) by polarizing a part of the emitted light beam in the given polarization direction (P), and to reflect another part of the emitted light beam by polarizing another part of the emitted light beam in another polarization direction (S); and an optical delay element (25c), which is arranged to receive the other part of the emitted light beam and polarize the other part of the emitted light beam in the given polarization direction.

5. System (1) according to any one of the preceding claims, characterized in that The linear polarizer device (25) is arranged to polarize the emitted light beam (F1) in the polarization direction P.

6. System (1) according to any one of the preceding claims, characterized in that The transmitting module (21) comprises a modulation unit (22), which is capable of receiving a data sequence and is arranged to modulate the emitted light beam (F1) from the received data sequence, and the receiving module (3) comprises a demodulation unit (33), which is connected to the photodetector (32a) and is arranged to extract the data sequence from the electrical signal converted by the photodetector.

7. System (1) according to the preceding claim, wherein: The modulation unit (22) is arranged to generate a pulse width modulated control signal, modulate the control signal from the received data sequence and control the emission of the light beam (F1) by the light emitting module (21) from the modulated control signal.

8. The system (1) according to any one of claims 6 or 7, characterized in that The system comprises a computing unit (4) arranged to detect the presence of a data sequence modulating the light beam (F1) emitted by the transmitting module (2) from a data sequence extracted at the demodulation unit (33) from an electrical signal converted by the photodetector (32a) from the light beam (F2) received by the receiving module (3), and to determine the flight time between the emission of the emitted light beam and the reception of the received light beam.

9. The system (1) as claimed in any one of the preceding claims, wherein: The transmitting module (2) is arranged so that the light beam (F1) participates completely or partially in the performance of a predetermined legal photometric function.

10. The lighting system (1) as claimed in any one of the preceding claims, characterized in that The transmitting module (2) and the receiving module (3) are arranged in the headlight of the motor vehicle.

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