FR3008568A1 - RESIDENTIAL NETWORK INSTALLATION FOR THE BROADCAST OF MULTIMEDIA SERVICES IN A DWELLING - Google Patents

Abstract

The invention relates to a residential network installation (200) comprising: - a patch cabinet (206) intended to be arranged in a technical housing (204) of a housing, - a subscriber modem router (210) for disposed in a housing part (202) and adapted to convert optical data signals it receives from an optical network (211) of an operator to electrical data signals; connection (207-209) intended to be distributed in different rooms (201-203) of the housing and adapted to be connected to multimedia broadcasting devices (218, 219), - a plurality of transmission cables (1), including a transmission cable (1) connecting the patch cabinet (206) to the subscriber modem router (210), and transmission cables (1) connecting the patch cabinet (206) to the connection jacks (207-209), in which the transmission cable (1) connecting the housing of br assage (206) to the subscriber modem router (210) comprises a first conductive assembly (3) comprising at least four metal conductors (5) adapted to transmit the electrical data signals to the patch cabinet (206) for transmission of the signals to the different connection sockets (207-209), and a second conductor assembly (4) comprising at least one optical fiber (9) adapted to transmit the optical data signals from the optical network (211) to the modem router subscriber (210).

Description

FIELD OF THE INVENTION The invention relates to a residential network installation for broadcasting multimedia services in a dwelling.

STATE OF THE ART Installations are known that comprise a brewing cabinet arranged in a housing technical sheath (GTL) whose function is to centralize multimedia services (telephony, terrestrial television, satellite television, Ethernet, television on the Internet, etc.). from different access networks and to disseminate these services in different parts of the housing. For this purpose, the patch cabinet is connected on the one hand to an external communication network via a cable (optical cable, copper twisted pair cable or coaxial copper cable) as well as to a terrestrial or satellite television antenna via a cable. coaxial cable, and secondly to a plurality of connection sockets distributed in the various parts of the housing via cables. Each connection socket allows the connection of a broadcasting device, such as a telephone, a television, a computer or any communication equipment operating on the basis of an Ethernet data exchange protocol. The connection sockets are for example standard RJ-45 type sockets. The patch cabinet is generally provided to receive a modem router (usually called "box") provided by a communication operator. The box has the function of directing the signals it receives and transmits to and from the access network to the external service operator to the patch cabinet according to the services concerned (telephony, Ethernet, WiFi). The patch cabinet is able to duplicate the telephony signals and the Ethernet signals that it receives from the box as well as the television signals that it receives from the antenna to send them back to the various connection sockets via the different cables. housing. The brewing box allows all services to be broadcast on each of the connection sockets of the house. The user can therefore connect each of the broadcast devices on any of the connection sockets. It can, according to the wishes, interchange terminal equipments (for example telephone and television). However, in this type of installation, the box is integrated into the box installed in the housing of the housing and is therefore inaccessible. However, some users wish to be able to control the box and use the functions specific to it (reset, access to the internal hard disk, stop WiFi services, tests, etc.). As a result, some users prefer not to connect the box 10 to the patch cabinet and install the box in a room of the housing, even connect their terminal equipment to the box over the air (WiFi) to access services in the home. all parts of the house. Such a configuration considerably reduces the interest of this type of installation since these users can no longer benefit fully from certain services (notably broadband transmission services). FR 2 952 777 describes a residential network installation for installing the box in a room of the housing, away from the brewing cabinet. For this purpose, the installation includes an offset cable for connecting the output of the box to a connection socket of the housing, so as to send the multimedia signals to the mixing cabinet for broadcasting services in the various rooms of the housing . However, the installation proposed in this document is not adapted to the use of an optical modem router (or optical box) whose input must be connected to an optical fiber. SUMMARY OF THE INVENTION An object of the invention is to enable a user to install an optical box away from the communication box, while fully benefiting from all the multimedia services.

This object is achieved within the framework of the present invention by means of a residential network installation comprising: - a patch cabinet intended to be arranged in a technical casing of a housing, - a subscriber modem router intended to be arranged in a a housing part and adapted to convert optical data signals it receives from an optical network of an operator, into electrical data signals, - a plurality of connection sockets for distribution in different rooms of the housing and adapted to be connected to multimedia broadcasting devices, - a plurality of transmission cables, including a transmission cable connecting the patch cabinet to the subscriber modem router, and transmission cables connecting the patch cabinet to connection jacks, wherein the transmission cable connecting the patch cabinet to the subscriber modem router includes a first set of emble conductor comprising at least four metal conductors adapted to transmit the electrical data signals to the patch cabinet 20 for transmission of the signals to the various connection sockets, and a second conductive assembly comprising at least one optical fiber adapted to transmit the signals of optical data from the optical network to the subscriber modem router. Thanks to the transmission cable connecting the patch cabinet to the subscriber modem router (or box), it is possible to have the modem remote from the patch cabinet, in a room of the housing. The modem router receives the optical data signals via the optical fiber of the cable and sends the converted signals back to the electrical data signals to the patch cabinet for broadcast to the different connectors of the housing. The installation may furthermore have the following features: the installation furthermore comprises a hybrid connection socket comprising an optical connector for connecting the subscriber modem router to the optical fiber of the cable and an electrical connector for connecting the modem modem with two metallic conductors, the transmission cable connecting the patch cabinet to the subscriber modem router comprises a sheath comprising a first sheath element surrounding a first cavity and a second sheath element surrounding a second cavity, the first a conductive assembly extending within the first cavity, the second conductive assembly extending within the second cavity, and the first sheath member and the second sheath member being separable to allow a independent connection of the first driver assembly and the second driver assembly, - the first assembly the conductor comprises two to four pairs of metal conductors; the metal conductors are twisted together in pairs; the second conductive assembly comprises three optical fibers, including a monomode optical fiber and two multimode optical fibers. PRESENTATION OF THE DRAWINGS Other characteristics and advantages will become apparent from the description which follows, which is purely illustrative and nonlimiting, and should be read with reference to the appended figures, among which: FIG. 1 is a diagrammatic sectional view; cross-section, a first cable structure; FIG. 2 schematically shows in cross-section a second cable structure; FIG. 3 is a schematic cross-sectional representation of a third cable structure; FIG. Figure 4 schematically represents a first residential network installation; Figure 5 schematically represents a second residential network installation; Figure 6 schematically represents a third residential network installation.

DETAILED DESCRIPTION OF AN EMBODIMENT In FIG. 1, the cable 1 represented comprises a sheath 2, a first conductive assembly 3 and a second conductive assembly 4.

The first conductive assembly 3 comprises four metal conductors 5 and a shielding envelope 6 surrounding the metal conductors. The four metal conductors 5 were twisted together in one operation to form a fourth of metal conductors. The quarter assembly has a small footprint compared to the assembly in the form of two twisted pairs. The metal conductors 5 are conductors comprising a conductive copper core and an insulating skin of thermoplastic material. The fourth metal conductor has an outer diameter equal to 2.17 millimeters. The shielding casing 6 is formed of an aluminum ribbon wound helically around the quarter. The shielding envelope 6 makes it possible to isolate the metal conductors 5, and in particular the metallic conductors 5 carrying television signals, in order to protect the television signals from interference. The quad metal conductors 5 can be used for the transmission of computer data type Ethernet 100 Megabits / s or for the transmission of analog type of telephone signals. For this purpose, the metallic conductors preferably exhibit a substantially constant attenuation in the frequency bands used for the broadcasting of digital or analog television. More precisely, in these frequency bands, the attenuation of the signal power transmitted by the metallic conductors has the following form: bxF-1 or a, b and c are coefficients which -eF are dependent on the characteristics of the metallic conductors and P is the frequency.

The second conductive assembly 4 comprises two optical conductors 7 and a reinforcing element 8. Each optical conductor 7 comprises a semi-tight optical fiber 9. The reinforcing element may be an aramid fiber reinforcing element.

The sheath 2 comprises a first sheath element 11 and a second sheath element 12. The first sheath element 11 surrounds a first cavity 13 within which the first conductive assembly 3 extends. The second sheath element 12 surrounds a second cavity 14 within which the second conductive assembly 4 extends. The sheath 2 has a junction zone 15 connecting the first sheath element 11 and the second sheath element 12. The junction zone 15 extends along a longitudinal direction of the cable between the first sheath element 11 and the second sheath element 12. The junction zone 15 constitutes a thinned area of least resistance of the sheath 2. The junction zone 15 is provided for tearing so as to allow separation of the first sheath element 11 and the second sheath element 12. This allows an independent connection of the first conductive assembly 3 and the second The sheath 2 is formed in one piece of material by extrusion around the first and second sets of conductors 3 and 4. The material forming sheath 2 is PVC (polyvinyl chloride) or LSOH material (material). at a low rate of smoke evolution and near absence of release of halogenated gases), such as polyethylene or filled polypropylene, for example. In FIG. 2, the cable 1 represented comprises a sheath 2, a first conductive assembly 3 and a second conductive assembly 4. The first conductive assembly 3 comprises four pairs 16 of insulated metal conductors, four shielding envelopes 17, each 30 shielding 17 surrounding a pair 16 of insulated metal conductors, and a shielding envelope 18 surrounding all pairs 16 of metal conductors with their respective envelopes 17.

Each pair 16 of metal conductors comprises two metal conductors 5 twisted together. The metal conductors 5 are conductors comprising a conductive copper core and an insulating skin of thermoplastic material.

Each shield casing 17 is formed of an aluminum ribbon wound helically around the pair 16 of metal conductors. The shielding envelope 17 makes it possible to isolate the metal conductors 5 from electromagnetic radiation, and in particular the metallic conductors carrying television signals, in order to protect the television signals from interference. The screening casing 18 extends between the pairs 16 of metal conductors and the sheath 2. The screening casing 18 is formed of an aluminum foil or a metal braid enveloping the pairs of conductors 16 metal.

The pairs of conductors include: - two pairs of conductors for the transmission of computer data at rates up to 100 Megabits per second, - a pair of conductors for the transmission of analog type telephone signals, and - a pair of conductors for the transmission of television signals. The second conductive assembly 4 comprises two optical conductors 7. Each optical conductor 7 comprises a semisealed optical fiber 9 and a protective envelope 10 surrounding the optical fiber 9. The outer diameter of the protective envelope is typically 2 millimeters. The sheath 2 comprises a first sheath element 11, a second sheath element 12 and a third sheath element 19. The first sheath element 11 consists of a first tube 30 surrounding a first cavity 13 inside which extends the first conductive assembly 3.

The second sheath element 12 consists of a tube surrounding a second cavity 14 inside which the second conductive assembly 4 extends. The first sheath element 11 and the second sheath element 12 are formed of PVC ( polyvinyl chloride) or a LSOH material (material with a low rate of smoke release and virtually no halogenated gas evolution), such as polyethylene or filled polypropylene, for example. The third sheath member 19 surrounds the first sheath member 11 and the second sheath member 12. More specifically, the third sheath member 19 includes a first portion 20 that surrounds the first sheath member 11, a second portion 21 that surrounds the second sheath element 12 and a connecting part 22 connecting the first part 20 and the second part 21 between them.

The joining portion 22 extends longitudinally between the first portion 20 and the second portion 21. The joining portion 22 constitutes a thinned area of least resistance of the third sheath member 19. The joining portion 22 is provided for tearing of in order to allow a separation of the first sheath member 11 and the second sheath member 12. The third sheath member 19 is formed in one piece of material by extrusion around the first and second sheath members 11 and 12. In the figure 3, the cable 1 shown is identical to the cable of FIG. 2, except that the second conductive assembly 4 comprises three optical conductors 7. Each optical conductor 7 comprises a semi-tight optical fiber 9. The three optical fibers 9 include a single-mode fiber 9A and two multimode fibers 9B. FIG. 4 schematically represents a first residential network installation 100 in a housing comprising several rooms 101 to 103 separated from each other by partitions and a technical sheath 104.

The illustrated installation 100 comprises an optical coupler 105, a patch cabinet 106, a plurality of cables 1, a plurality of transceiver modules 107 and a plurality of connection jacks 108.

The optical coupler 105 and the patch cabinet 106 are arranged in the technical sheath 104 of the housing (GTL). The transceiver modules 107 and the connection jacks 108 are distributed in the various rooms 101 to 103 of the housing. The cables 1 are cables conforming to the cable of FIG. 1, FIG. 2 or FIG. 3. The cables 1 connect the transceiver modules 107 to the optical coupler 105 and the connection jacks 108 to the patch cabinet 106. More specifically, each transceiver module 107 disposed in a part 101, 102, 103 of the housing is connected to the optical coupler 105 disposed in the technical sheath of the housing 104 via the second conductive assembly 4 of the cable 1. The optical coupler 105 its function is to provide a link between the optical fibers 9 of the various cables 1 of the installation, in order to transmit data from one cable 1 to the other and to allow data exchanges between several user terminals 109 and 110. Each transceiver module 107 is configured to convert the optical data signals transmitted by the cable 1 into radio frequency data signals, and to transmit the radiofrequency data signals. According to a wireless communication protocol to a user terminal 109, 110 present in the room 101, 103. The transceiver module 107 is also configured to receive the radio frequency data signals transmitted by a user terminal 109, 110. according to a wireless communication protocol, and for converting the radio frequency data signals into optical data signals which are transmitted by the cable 1. For this purpose, the transceiver module 107 is connected to the two optical conductors 7, one of the optical conductors 7 being used for transmitting data signals from the optical coupler 105 to the transceiver module 107 (in the upstream direction) and the other optical conductor 7 being used to transmit data from the transceiver module 107 to the optical coupler 105 (in the downward direction). The installation 100 allows a data exchange between the different user terminals 109, 110 equipped with transceiver modules 111 present in the housing. For this purpose, a first user terminal 109 present in a first piece 101 transmits a radio frequency data signal 112 according to a wireless communication protocol. The data signal 112 is received by a first transceiver module 107 located near the user terminal 109. The first transceiver module 107 converts the data signal 112 that it receives into an optical signal 113 and transmits the optical signal. 113 on an optical fiber 9 of the optical conductor 7 of a first cable 1. The signal 113 is transported by the optical fiber 9 of the first cable 1 to the optical coupler 105. The optical coupler 105 receives the optical signal 113 and the reemitting on the optical fiber 9 of a second cable 1. The signal 113 is transported by the optical fiber 9 of the second cable 1 to a second transceiver module 107. The second transceiver module 107 converts the optical signal 113 that it receives in a radio frequency data signal 114 and transmits the data signal 114 to a second user terminal 110 located near the second transceiver module 107 according to the protocol the wireless communication. The installation 100 also allows the broadcasting of services such as wired telephone and digital terrestrial television (DTT) or satellite 25 in the various rooms 101 to 103 of the housing. The purpose of the brewing cabinet 106 is to centralize multimedia services (telephony, terrestrial television, satellite television, Ethernet, Internet television, etc.) from different access networks and to broadcast these services in the various rooms 101 to 103 of the dwelling. For this purpose, the mixing cabinet 106 is connected on the one hand to an external communication network (not shown) as well as to a terrestrial or satellite television antenna (not shown), and on the other hand to different connection jacks 108 distributed in the various parts 101 to 103 of the housing via the first conductive assemblies 3 of the cables 1. Each connection socket 108 allows the connection of a device 115, 116, such as a wired telephone, a television, a computer or any communication equipment operating on the basis of an Ethernet data exchange protocol. The connection jacks 108 are for example RJ-45 standard jacks. Each cable 1 has a first end connected to the optical coupler 105 and to the patch cabinet 106 and a second end connected to a transceiver module 107 and to a connection socket 108. The first sheath element 11 and the second sheath element 12 are separated from each other at each end of the cable 1. The separation of the sheath elements 11 and 12 makes it possible, at the first end of the cable 1, to connect the first conductive assembly 3 to the patch cabinet 106 and the second conductive assembly 4 to the optical coupler 105. This also allows, at the second end of the cable, to connect the first conductive assembly 3 to the connection socket 108 and the second conductive assembly 4 to the transceiver module 107 Figure 5 schematically shows a second residential network installation 200 in a housing comprising a plurality of separate rooms 201 to 203. The illustrated system 200 comprises an optical interior termination device (DTIO) 205, a patch cabinet 206, a plurality of cables 1, a plurality of connection sockets. 207 to 209 and an optical modem router 210 (or optical box). The optical internal termination device 205 is connected on the one hand to an optical fiber 211 of an operator's communication network extending outside the housing and on the other hand to a subscriber optical cord 30 212, and serves as an interface point between the communication network and the residential network. The brewing cabinet 206 serves to centralize multimedia services (telephony, terrestrial television, satellite television, Ethernet, Internet television, etc.) from different access networks including the operator's communication network, and to diffuse these services in the different rooms 101 to 103 of the housing. For this purpose, the mixing cabinet 206 is connected on the one hand to the optical inner termination device 205 via the optical cord 212, and on the other hand to the various connection sockets 207 to 209 distributed in the various pieces 201 to 203 of the housing via the cables 1. The connection sockets 207 to 209 are distributed in the various rooms 201 to 203 of the housing.

The cables 1 are cables conforming to the cable of FIG. 1, of FIG. 2, or of FIG. 3. The cables 1 connect the connection jacks 207 to 209 to the patch cabinet 206. One of the connection jacks 208 is a hybrid plug comprising an optical connector 213 and a copper connector 214 of the RJ-45 type. The optical box 210 is connected to the cable 1 by means of an optical cord 215 connected to the optical connector 213 and an Ethernet cord 216 connected to the copper connector 214. More specifically, the optical box 210 is connected firstly to the second conductor assembly 4 of the cable through the optical cord 215, and secondly to the first conductive assembly 3 of the cable by the Ethernet cable. The other jacks 207 and 209 may be jacks comprising only an RJ-45 type connector or identical hybrid jacks to the connection junction 208. Each connection junction 207 to 209 allows the connection of a device 218, 219, such as a wired telephone, a television, a computer or any communication equipment operating on the basis of an Ethernet data exchange protocol. The installation 200 allows the user to place the optical box 210 30 in a room 202 of the housing (and not in the technical sheath of the housing 204), while taking full advantage of all services from the box (voice , data and images over IP) on each of the connection jacks 207 to 209 of the housing. In this way, the user can control the box 210 and use the functions specific to it (reset, access to the internal hard disk, stop wireless communication services, tests, etc.). FIG. 6 schematically shows a third residential network installation 300 in a housing comprising a plurality of parts 301 to 303 separated from each other by partitions and a technical jacket 304. The illustrated installation 300 comprises an optical interior termination device. (DTIO) 315, an optical coupler 305, a patch cabinet 306, a plurality of cables 1 and 1 ', a plurality of transceiver modules 307 and a plurality of connection sockets 308 and 309. Cables 1 and 1 The optical inner termination device (DTIO) 315, the optical coupler 305 and the patch cabinet 306 are arranged in the technical housing sleeve 304 (GTL). The optical internal termination device 315 is connected on the one hand to an optical fiber 321 of an operator's communication network 20 extending outside the housing and on the other hand to a monomode optical fiber 9A of the cable 1 '. The optical internal termination device 315 serves as an interface point between the communication network and the residential network. The cables 1 connect the transceiver modules 307 to the optical coupler 305 and the connection sockets 308 to the patch cabinet 306. The transceiver modules 307 and the connection sockets 308 are distributed in the various housing parts 301 to 303. . More specifically, each transceiver module 307 disposed in a housing part 301, 302, 303 is connected to the optical coupler 305 disposed in the housing of the housing 304 via the second conductive assembly 4 of the cable 1 or 1 '.

The optical coupler 305 serves to provide a link between the multimode optical fibers 9B of the various cables 1 (or 1 ') of the installation, in order to transmit data of a cable 1 (or 1') to the another and to allow data exchange between multiple user terminals 319 and 320. Each transceiver module 307 is configured to convert the optical data signals transmitted by the cable 1 (or 1 ') to radio frequency data signals, and for transmitting the radio frequency data signals according to a wireless communication protocol to a user terminal 319, 320 present in the room 301, 303. The transceiver module 307 is also configured to receive the radio frequency data signals transmitted by a user terminal 319, 320 according to a wireless communication protocol, and for converting the radio frequency data signals to optical data signals that are transmitted by the cable 1 (or 1 '). For this purpose, the transceiver module 307 is connected to the two multimode optical fibers 9B, one of the multimode optical fibers 9B being used to transmit data signals from the optical coupler 305 to the transceiver module 307 (in the amount) and the other multimode optical fiber 9B being used to transmit data from the transceiver module 307 to the optical coupler 305 (downstream). As in the case of the installation 100 of FIG. 1, the installation 300 allows data exchange between the different user terminals 309, 310 equipped with transceiver modules 311 present in the housing. The installation 300 shown also comprises an optical modem router 310 (or optical box) disposed in one of the parts 302 of the housing. The optical box 310 is connected to the cable 1 'by means of an optical cord 315 connected to the connection socket 309. Specifically, the optical box 310 is connected to the single mode fiber 9A of the cable 1' by the optical cord 315. In this way, the optical box 310 is connected to the fiber 321 of the external network through the cable 1 '.

Furthermore, the optical box 310 also comprises a transceiver module 311 configured to exchange data signals with a radio frequency transmitter-receiver module 307 according to a wireless communication protocol.

Each transceiver module 307 is connected to the multimode fibers 9B of the cable 1 or 1 '. In this way, the optical box 310 can send the optical data signals it receives from the external network (in the upstream direction) to the optical coupler 305 for broadcast to the different transceiver modules 307 of the housing. Similarly, the optical box 310 may return signals of radio frequency data that it receives from the user terminals 319, 320 to the fiber 321 (in the downward direction). The installation 300 allows the user to place the optical box 310 in a room 302 of the housing (and not in the technical housing of the housing 304), while fully benefiting from all services from the box (voice, data and images over IP) on each of the transceiver modules 308 of the housing. In this way, the user can control the box 310 and use the functions specific to it (reset, access to the internal hard disk, stop wireless communication services, tests, etc.). Moreover, as in the case of the installation of FIG. 1, the installation 300 allows the broadcasting of services such as wired telephone and digital terrestrial television (DTT) or satellite in the different rooms 301 to 303 of the dwelling. . The purpose of the patching cabinet 306 is to centralize multimedia services (telephony, terrestrial television, satellite television, Ethernet, Internet television, etc.) from different access networks and to broadcast these services in the various rooms 301 to 303 of the housing. For this purpose, the patch cabinet 306 is connected on the one hand to an external communication network (not shown) as well as to a terrestrial or satellite television antenna (not shown), and on the other hand to different connection jacks 308 distributed in the various parts 301 to 303 of the housing via the first conductive assemblies 3 of the cables 1. Each connection socket 308 allows the connection of a device 315, 316, such as a corded telephone, a television, a computer or any communication equipment operating on the basis of an Ethernet data exchange protocol.

Claims (6)

REVENDICATIONS1. A home network installation (200) comprising: - a patch cabinet (206) to be disposed in a technical housing (204) of a housing, - a subscriber modem router (210) to be disposed in a piece (202) of the housing and adapted to convert optical data signals it receives from an optical network (211) of an operator to electrical data signals, a plurality of connection sockets (207). -209) intended to be distributed in different rooms (201-203) of the housing and adapted to be connected to multimedia broadcasting devices (218, 219), - a plurality of transmission cables (1), including a transmission cable (1) connecting the patch cabinet (206) to the subscriber modem router (210), and transmission cables (1) connecting the patch cabinet (206) to the jacks (207-209), wherein the transmission cable (1) connecting the patch cabinet (206) to the m The subscriber router (210) comprises a first conductive assembly (3) comprising at least four metal conductors (5) adapted to transmit the electrical data signals to the patch cabinet (206) for transmission of the signals to the different outlets. connector (207-209), and a second driver assembly (4) comprising at least one optical fiber (9) adapted to transmit the optical data signals from the optical network (211) to the subscriber modem router ( 210). The apparatus of claim 1, further comprising a hybrid connection socket (208) comprising an optical connector (213) for connecting the subscriber modem router (210) to the optical fiber (9) of the cable (1). ) and an electrical connector (214) for connecting the subscriber modem router (210) to the two metal leads (5). 3. Installation according to one of claims 1 and 2, wherein the transmission cable (1) connecting the patch cabinet (206) to the subscriber modem router (210) comprises a sheath (2) comprising a first element of sheath (11) surrounding a first cavity (13) and a second sheath member (12) surrounding a second cavity (14), the first conductive assembly (3) extending within the first cavity (13) the second conductive assembly (4) extending within the second cavity (14), and wherein the first sheath member (11) and the second sheath member (12) are separable to allow a 10 independent connection of the first conductive assembly (3) and the second conductive assembly (4). 4. Installation according to claim 3, wherein the first conductive assembly (3) comprises two to four pairs (16) of 15 metal conductors (5). 5. Installation according to one of claims 3 and 4, wherein the metal conductors (5) are twisted together in pairs (16). 20 6. Installation according to one of claims 1 to 5, wherein the second conductive assembly comprises three optical fibers (9), including a monomode optical fiber (9A) and two multimode optical fibers (9B).