FR2949935A1 - Multimedia system for distributing e.g. satellite TV signal in teaching establishment, has return channel device comprising concentrator for receiving return signals on twisted pairs for injecting return signals in coaxial cable - Google Patents

Abstract

The system (10) has baluns (14-17) for receiving high frequency signals via a coaxial cable and for emitting the signals on twisted pairs (102-108). A return channel device (400) transmits return signals on the twisted pairs simultaneously to the transmission of high frequency signals. The return channel device has a concentrator for receiving the return signals on the twisted pairs for injecting the return signals in the coaxial cable.

Description

A system for distributing high frequency signals in a twisted pair wired network having a return path device and a mixing device. The present invention relates to a multimedia system for distributing high frequency signals in a twisted pair cable network comprising a return path device. It also relates to a multimedia system for distributing high frequency signals in a twisted pair cable network comprising a device for mixing high frequency signals. The present invention finds a particularly advantageous application in the field of the distribution of television channels, the Internet, the satellite signal and the analogue or digital telephone in places such as residential and public or collective institutions 15 (teaching, hospitals, hotels). Multimedia systems for distributing high frequency signals in a twisted pair cable network such as the system described in WO 2006/042978 are known. The system described in this document enables the distribution of high frequency signals in a twisted pair wired network by means of a splitter comprising at least one impedance matching means for receiving high frequency signals via a coaxial cable and for transmitting on at least one twisted pair said high frequency signals. The splitter is designed by iteratively calculating and from the characteristics of the splitter components, a value of IP3 and a gain value at the output of the splitter, each iteration corresponding to an amplification stage. In one of the embodiments described in this document, it is proposed to add a return channel to the system described in this document by using a second twisted pair as a return path to a first twisted pair carrying the high frequency signals. second twisted pair can not then convey the high frequency signals to be distributed in the wired network in twisted pairs. However, the use of a twisted pair as a return path, as proposed in WO 2006/042978, for each twisted pair carrying the high frequency signals would halve the number of twisted pairs available in the network for conveying the high frequency signals.

In the following, balun means an impedance matching system 5 for connecting a symmetrical twisted pair cable (BALanced) to an asymmetrical coaxial cable (UNbalanced, with ground line).

An object of the present invention is to overcome the disadvantage. Another object of the present invention is to provide a multimedia system for distributing high frequency signals in a more complete and more efficient twisted pair cable network. It is another object of the present invention to provide a multimedia high frequency signal distribution system in a twisted pair wired network having a return path device that does not decrease the number of twisted pairs available in the network.

The invention makes it possible to achieve at least one of the above objectives with a multimedia high-frequency signal distribution system in a twisted pair cable network, comprising means for conveying high frequency signals, said means comprising a splitter and at least one impedance matching means for receiving high frequency signals via a coaxial cable and for transmitting on at least one twisted pair said high frequency signals, said system being characterized in that it further comprises a return path device on said at least one twisted pair, simultaneously with the transmission of said high frequency signals by said twisted pair, said return path device comprising a stage concentrator for receiving said at least one feedback signal on said at least one minus one twisted pair for injection into said coaxial cable. The system according to the invention proposes to use, thanks to a return path device, each twisted pair conveying the high frequency signals as a return path. Each twisted pair thus simultaneously transmits in one direction the high frequency signals and in the other direction the feedback signal. The number of twisted pairs for the distribution of high frequency signals is therefore not decreased with the system according to the invention. The system according to the invention is therefore more efficient and more efficient than the systems of the state of the art since it makes it possible to integrate the return path without impairing the distribution capacity of the high frequency signals. The system according to the invention can be applied for the distribution of high frequency signals ranging from 2 to 2350 MHz over twisted pairs of category 5, 6, 7 or grade 3 according to the UTE guide C90-483-1. The signals conveyed may include the following signals: io - Ethernet 10/100, - IP TV from an operator box or a digital video server, - Modulated satellite TV (BIS band 950-2150 MHz), - UHF / VHF analog TV and / or digital (DTT), - TV UHF / VHF CATV, 15 - FM band (88-108MHz), and / or - IP and / or analog telephony. The invention makes it possible to simultaneously convey on the same twisted pair the TV and radio signals listed and the return channel. According to a nonlimiting exemplary embodiment, the return channel makes it possible to transport signals of frequencies ranging from 5 to 65 MHz.

The return path device may further comprise for each twisted pair carrying a feedback signal, at least one means for separating the feedback signal from said high frequency signals conveyed simultaneously by said twisted pair.

According to an exemplary embodiment of the system according to the invention, the at least one means for separating the return signal and the high frequency signals conveyed simultaneously by a twisted pair may comprise a power divider for each twisted pair.

Advantageously, for n twisted pairs, the concentrator may comprise x stages with n = 2x. On each floor, the return channels are mixed in pairs to obtain at the output of the concentrator a single return channel for all the twisted pairs. The mixture of the signals conveyed by two return channels may be realized by a divider receiving the return signals coming from two different return channels or two sets of return signals previously mixed and providing a single channel conveying all of these signals. return signals. Each divider can be followed by a bandpass filter to improve the retrieval of return signals on each return channel. For n twisted pairs, the concentrator may comprise 2 "-1 divisors, each of said divisors performing the mixing of signals from two channels.

According to a first embodiment, when the concentrator comprises an input channel not connected to a load, said input channel 15 can be terminated by an impedance plug so as to avoid the radiation of the electromagnetic disturbances.

According to a second embodiment of the system according to the invention, when the concentrator comprises an input channel not connected to a load, said input channel may comprise a directional coupler for controlling the power supply of the last stage of the power supply. amplification of the channel concerned as a function of the presence or absence of a charge, so as to avoid the radiation of electromagnetic disturbances.

Advantageously, the return path device of the system according to the invention may further comprise means for injecting all of the mixed return signals into the coaxial cable carrying the high frequency signals. The stage concentrator receives all of the feedback signals and provides a single channel comprising mixing all of the return signals of all the return channels. This global feedback signal is then injected into a coaxial cable which can be the one that carries the high frequency signals distributed in the wired network in twisted pairs. Advantageously, the means for injecting all the return signals into the coaxial cable comprise means for amplifying the set of return signals.

The means for injecting all return signals into the coaxial cable may further comprise an attenuator arranged downstream of the amplifier.

According to another aspect of the invention there is provided a multimedia system for distributing high frequency signals in a twisted pair wired network, comprising means for carrying high frequency signals, said means comprising a splitter with at least one means for distributing impedance matching for receiving high frequency signals via a coaxial cable and transmitting it over at least one twisted pair said high frequency signals further comprising at least one mixing device, said mixing device comprising a stage concentrator for mixing several signals of different frequency bands for transporting said signals on at least one twisted pair. The multimedia high frequency signal distribution system 20 in a twisted pair wired network comprising at least one mixing device may be the system described above and also comprising a return path device. The invention thus also proposes a multimedia system for distribution of high frequency signals in a twisted pair wired network comprising: a return path device as described above, and / or a mixing device as described in FIG. the following.

The mixing device of the system according to the invention may comprise at each of these inputs: an amplifier, an attenuator, and a slope filter, arranged between said amplifier and said attenuator, the slope of which depends on the band of signal frequency associated with this input. Indeed, the studies carried out by the inventors show that the attenuation of the signals depends on the frequency of the signals concerned. Since the purpose of the mixing device is to mix the high frequency signals with equal amplitude, the slope of the slope filter depends on the frequencies. For example, at current transmitter power levels, the system uses 15 dB for the 50 to 865 MHz frequency band and 30 dB for the 950 to 2150 MHz frequency band.

For n inputs, the concentrator of the mixing device can have x stages with n = 2x.

According to a first non-limiting embodiment of the system according to the invention, when the concentrator of the mixing device comprises an input channel not connected to a load, said input channel can be terminated by an impedance plug of to avoid electromagnetic disturbances.

According to a second nonlimiting embodiment of the system according to the invention when the concentrator of the mixing device comprises an input channel not connected to a load, said input channel may comprise a directional coupler for controlling the power supply. electrical amplifier of the last stage of amplification of the channel concerned as a function of the presence or absence of a load, so as to automatically avoid electromagnetic disturbances 25 According to the invention, the distributor may comprise a structure with amplification stages in cascade, said splitter being designed by carrying out the following operations: - it is calculated iteratively and from the characteristics of the splitter components, a value of IP3 and a gain value at the output of the splitter, each iteration corresponding to an amplification stage, - at each iteration, the computed IP3 and gain values are compared with predicted instructions When the instructions are respected, the splitter is designed with a number of amplification stages equal to the number of iterations carried out.

Other advantages and features of the invention will become apparent on examination of the detailed description of an embodiment which is in no way limitative, and the appended drawings, in which: FIG. 1 is a simplified general view of a system according to the invention for distributing high frequency signals comprising a return path device and a mixing device; Figure 2 is a simplified schematic view of a signal distribution device and a return path device of Figure 1; and - Figure 3 is a simplified schematic view of the mixing device of Figure 1;

In the figures the elements appearing in several figures retain the same reference.

FIG. 1 is a simplified general view of a system 10 for distributing high frequency signals according to the invention in a network 20 wired in twisted pairs. The system 10 allows the distribution of high frequency signals from a satellite antenna 11, a CATV cable television network denoted 12, an antenna 13 UHF / VHF FM signal transmission. The system 10 also allows the management and distribution of Ethernet / Info signals and digital and analog telephony signals. The system 10 allows a distribution of the high frequency signals in a network of twisted pairs. In the example described here, the network comprises 4 cables of 4 twisted pairs referenced 110-140. For ease of reading cables 120 and 130 are not shown. The system 10 comprises a mixing device 300 mixing the signals from the sources 11-13, a device for the distribution of the signals 200 and a return path device 400. The mixing device 300 and the channel device back 400 will be described below. The system also includes a satellite return path device 35 500 carrying the satellite return channel, a switch / Info 600 device for passing the Ethernet / Info signal over two twisted pairs 112 and 114, and a device switch 700 for switching digital and analog telephony signals over a twisted pair 116. The system 10 also includes concentrators 18-21, concentrating all of the applications on each of the cables 110-140. The system according to the invention further comprises baluns baluns 14-17 for passing signals from a coaxial cable to a twisted pair at the output device for the distribution of the signals 200. There are as many baluns baluns as pairs twisted. Of course, the system also includes asymmetrizing baluns (not shown) allowing the passage of the signals of a twisted pair to a coaxial cable

The distribution of the signals is carried out as follows. The signal distribution device 200 enables a distribution of the signals from the mixing device 300 to four twisted pairs 102-108. Each of the twisted pairs 102-108 is then connected to a hub 18-21. Each concentrator 18-21 thus receives a mixture of the signals from the sources 11-13 through a twisted pair. 20 Furthermore, each concertator 18-21 receives from the switch device 600 two twisted pairs 112 and 114 carrying the Ethernet / Fast Ethernet applications. Finally each concertator 18-21 receives from the switch device 700 a twisted pair 116 conveying the digital or analog telephony signal. In the end, each concertator 18-21 receives four twisted pairs and realizes the concentration of all the signals on a twisted pair cable 110-140 comprising four twisted pairs. According to the current UTE C90 483 standardization, all the domestic applications are concentrated on the same twisted pair cable 110-140 as follows: - 1 pair for the TV and radio signals, - 1 pair for the signals of analog or digital telephony, - and 2 pairs for Ethernet / Fast Ethernet applications. FIG. 2 is a simplified schematic view of a signal distribution device 200 and a return path device 400.

The signal distribution device 200 receives from the mixing device 300 the mixture of the signals from the sources 11-13 and distributes these signals over the four twisted pairs 102-108 via the symmetrizing baluns 14-17. The distribution device 200 comprises a stage distributor 202 disposed downstream of an attenuator 204. In the present example, the distributor 202 has two stages for one input and four outputs.

By respecting the propagation direction of the signals, the distributor comprises, at its first stage an amplifier 206 and a divider 208, at its second stage two amplifiers 210 and 212 each disposed upstream of a power divider, respectively 214 and 216. Each output of the distribution device is provided with a 5-88 MHz low-pass filter, referenced 218-224.

The return path device 400 comprises for each twisted pair 102-114 a power divider respectively 402 to 408. The power dividers 402-408 are arranged downstream of the baluns baluns 14-17 in the direction of return for each of the pairs twisted. The return signal for each of the twisted pairs 102-114 is then injected at the input of a stage concentrator 410 for mixing the return signals in pairs. In the present example, for 4 twisted pairs, the tier concentrator 410 has two stages and 4 inputs and a single output. At the first stage, the concentrator 410 comprises two dividers: the divider 412 mixing the return signals carried by the twisted pairs 102 and 104 and the divider 404 mixing the return signals carried by the twisted pairs 106 and 108. downstream of each divider 412 and 414, the concentrator 410 comprises a band-pass filter, respectively 416 and 418. At the second stage, the stage concentrator comprises a divider 420 for mixing the signals coming from the band-pass filters 416 and 418 and provides a unique signal. This single signal is filtered by a bandpass filter 422. Finally the concentrator 410 provides at its output 424 a single signal 2949935 - 10 - corresponding to the mixture of all the return signals carried by each of the twisted pairs 102 to 108 The single signal obtained at the output of the concentrator 410 is then amplified by an amplifier 426 then attenuated by an attenuator 428 and injected into a coaxial cable carrying high frequency signals. The return path device 400 allows each twisted pair 102, 104, 106 and 108 to carry simultaneously: - the high frequency signals from the sources 11-13, and - one or more return signals in the opposite direction to the transport of the signals high frequencies from sources 11-13.

FIG. 3 is a simplified schematic view of the high frequency signal mixing device 300. The mixing device 300 has two input channels 302 and 304. The input channel 302 is connected to the antenna 11 and the channel input channel 304 is connected to the antenna 13. Each input channel 302 and 304 comprises, in the order: - a broadband amplifier, respectively 306 and 308 amplifying the signals from the sources 11 to 13; a slope filter, respectively 310 and 312, and an attenuator, respectively 314 and 316. Each slope filter 310 and 312 has a different slope adapted to the frequency of the signals on the corresponding input channel so that at the output of the attenuator 314 and 316, the amplitudes on each input channel 302 and 304 are equal. The mixing device comprises, downstream of the attenuators 314 to 316, a stage concentrator 318 making it possible to mix the various high frequency signals transported on the input channels 302 and 304. The concentrator 318 comprises in the present example two inputs, one input single exit and one floor. The concentrator 318 comprises a divider 320 for mixing the signals coming from the input channels 302 and 304. At the output of the divider 320, the concentrator 318 comprises an amplifier 322 amplifying the mixed signals.

Of course, a high frequency signal distribution system 5 may have a plurality of concentrator devices 300 to satisfy normalization rules, or a concentrator device having a plurality of stages. For example, currently the current UTE C90 483 standardization provides for the use of 4-pair twisted pair cables. This standardization provides that two pairs are used for Ethernet, a pair for the telephone and one for TV and radio signals. In this case, the system according to the invention may comprise several concentrator devices according to the invention for the concentration of: - all the TV or radio signals on the same twisted pair including the return channel, 15 - the set domestic applications within the same twisted pair cable: 1 pair for TV and radio signals, 1 pair for analogue or digital telephony signals, and 2 pairs for Ethernet / Fast Ethernet applications.

The present invention is for example intended for the distribution of high frequency signals in hotels, the tertiary sector, educational premises or in the residential sector.

The distribution device 200 may be designed in the manner described in WO 2006/042978. As described in this document, the distribution device may comprise a stage distributor comprising amplifiers. The choice of amplifiers and the structure of the splitter can be guided by the following formula: IP3 (output) = IP3 (2) -101og (1 + 1 iz) g2

In fact, this equation can be repeated as many times as necessary to achieve a desired IP3 value. Each iteration corresponds to a stage of the splitter. If to reach a given IP3 it is necessary to carry out four iterations, then the splitter will have four amplification stages.

The example described relates to a network of four twisted pairs, but one skilled in the art can apply the invention to a network of n twisted pairs without difficulties.

Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

Claims (16)

REVENDICATIONS1. A multimedia high-frequency signal distribution system (10) in a twisted pair wired network, comprising means for carrying high frequency signals, said means comprising a splitter (202) and at least one impedance matching means (14) 17) for receiving high frequency signals via a coaxial cable and for transmitting it on at least one twisted pair (102-108) said high frequency signals, said system being characterized in that it further comprises a device for return path (400) on said at least one twisted pair (102-108), simultaneously with the transmission of said high frequency signals by said twisted pair (102-108), said return path device (400) comprising a concentrator to stages (410) for receiving said at least one feedback signal on said at least one twisted pair (102-108) for injection into said coaxial cable. The system of claim 1, characterized in that the return path device (400) comprises, for each twisted pair (102-108), at least one means (402-408) for separating the return signal from said high frequency signals conveyed simultaneously by said twisted pair (102-108). 3. System according to claim 2, characterized in that the at least one means for separating the return signal and the high frequency signals conveyed simultaneously by a twisted pair (102-108) comprises a power divider (402-408). ) for each twisted pair (102-108). 4. System according to any one of the preceding claims, characterized in that for n twisted pairs, the concentrator (410) 30 has x stages with x = 2 ". 5. System according to any one of the preceding claims, characterized in that, for n twisted pairs, the concentrator (410) comprises at least 2 "-1 dividers (412,414,420), each of said dividers (412,414,420) making the mixture two-way signals 2949935 - 14 - A system according to any one of the preceding claims, characterized in that when the concentrator (410) has an input path not connected to a load, said input path is terminated by an impedance plug so as to to avoid electromagnetic disturbances. A system as claimed in any one of the preceding claims, characterized in that when the concentrator (410) has an input path not connected to a load, said input path comprises a directional coupler for controlling the power supply. the last stage of amplification of the channel concerned as a function of the presence or absence of a load, so as to avoid electromagnetic disturbances. 8. System according to any one of the preceding claims, characterized in that the return path device (400) further comprises means (426, 428) for injecting all the return signals into the coaxial cable conveying the signals. high frequency. 9. System according to claim 8, characterized in that the means for injecting all return signals into the coaxial cable comprise means for amplifying said signals. 10. System according to claim 9, characterized in that the means for injecting all return signals into the coaxial cable comprise an attenuator (428) disposed downstream of the amplifier (426). 11. System according to any one of the preceding claims, characterized in that it comprises, upstream of the distributor (202), at least one mixing device (300), said mixing device (300) comprising a concentrator with stage (318) for mixing several signals of different frequency bands for transporting said signals on at least one twisted pair (102-108). 12. System according to claim 11, characterized in that the mixing device (300) comprises at each of these inputs (302, 304): an amplifier (306, 308), an attenuator (314, 316); ), and a slope filter (310, 312) disposed between said amplifier (310, 312, 314) and said attenuator (322, 324, 326), the slope of which depends on the frequency band of the signal associated with this entry. 13. System according to any one of claims 11 or 12, characterized in that for n inputs, the concentrator (318) of the mixing device io comprises x stages with n = 2X. 14. System according to any one of the preceding claims, characterized in that when the mixing device comprises an input channel not connected to a load, said input channel is terminated by an impedance plug so as to avoid electromagnetic disturbances. 15. System according to any one of the preceding claims, characterized in that when the concentrator comprises an input channel not connected to a load, said input channel comprises a directional coupler 20 for controlling the power supply of the latter. amplification stage of the concerned channel depending on the presence or absence of a load, so as to avoid electromagnetic disturbances 16. System according to any one of the preceding claims, characterized in that the splitter (200) comprises a cascaded amplification stage structure, said splitter being designed by performing the following operations: - it is calculated, iteratively and from the characteristics of the splitter components, a value of IP3 and a gain value at the output of the splitter, each iteration corresponding to an amplification stage, - at each iteration, the values of IP3 and calculated gains at predetermined setpoints, and - when the instructions are met, the splitter is designed with a number of amplification stages equal to the number of iteration carried out.