This application is the U.S. National Stage of PCT/EP2010/070380, filed Dec. 21, 2010, which in turn claims priority to French Patent Application No. 0959574, filed Dec. 24, 2009, the entire contents of all applications are incorporated herein by reference in their entireties.
The present invention concerns an installation for emission/reception of hyperfrequency radioelectrical satellite signals.
Currently, the broadcast diffusion of television programmes by satellite is widely used throughout the world. Numerous devices are installed at millions of users. The installed devices are predominantly reception devices which comprise an exterior unit including a parabolic reflector which focuses the modulated hyprefrequency signals, on the source, designated a cornet, of an LNB (Low Noise Block, which means a reception block), with the LNB transforming the received hyperfrequency signals into electrical signals in intermediate satellite band so as to transmit them by means of a coaxial cable to an interior unit commonly designated a satellite decoder or else STB (Set Top Box). The decoder comprises a demodulation block which extracts a “useful” modulated signal in the modulated signal transmitted on the coaxial cable and demodulates the extracted “useful” signal. The demodulated “useful” signal can, for example, be used for the display of video images on a television screen.
Today, satellite operators essentially offer services for the transport of television channels, these services being purely passive, i.e. a one-way service.
It can, however, prove useful to be able to offer services requiring a return link; this is the case, for example, in interactive services (votes, consumption of contents with conditional access by key exchange, orders for new services such as video on demand). More generally, this return link can find particularly interesting applications in the field of machine-to-machine communications or M2M to control certain equipment (alarm, heating, . . . ) present within the home.
The majority of satellite television services which are offered do not integrate a return link, with the exception of services such as the Tooway™ service which constitutes a bidirectional high-speed access service to the internet by satellite based for example on the SurfBeam™ DOCSIS™ technology. A service such as the Tooway™ service can, however, equip a limited number of users and, moreover, requires bulky equipment which is difficult to install (heavy antenna supports, the obligation to add a second antenna or to replace the existing antenna and the passing of one or two additional coaxial cables).
Another example of a bidirectional satellite television diffusion system is described in the patent document EP0888690; this system uses a broadband forward link Ku and a narrowband return link L. Again, this system is cumbersome, complex and costly in that it requires the presence of two reflectors (for each band Ku and L) or of one dedicated reflector comprising a reflector suited to receive Ku band signals and integrating a band L transmission antenna. This system also involves the presence of two physical paths for the routing of data, one from the Ku band antenna towards the decoder inside the house and the other from the decoder towards the L band antenna. It will be readily understood that this type of installation involves a complete change of the standard systems currently equipping households and a not inconsiderable additional cost.
Another solution consists in using a return link using a connection of the ADSL type provided by fixed telephony operators (STN or “Switched Telephone Network”) or a connection of the GPRS/UMTS type provided by mobile telephony operators. This solution therefore necessitates considerable and costly supplementary equipment and also an additional subscription; furthermore, the telephonic switching is not particularly suited to the transmission of smaller messages such as voting or command messages.
In this context, the present invention aims to provide an installation for the emission/reception of hyperfrequency radioelectrical satellite signals which is efficient in terms of performance, is also very easily adaptable to a pre-existing installation, is low in cost and is particularly suited to M2M applications.
To this end, the invention proposes an installation for the emission/reception of hyperfrequency radioelectrical satellite signals comprising:
Owing to the invention, advantageously the gain of the reflector used to receive the hyperfrequency signals in the first band (for example the Ku or Ka band) is used to transmit the return link signals in the second frequency band for example comprised between 1.5 and 5 GHz (i.e. the frequencies of band S). The gain of the reflector allows one to avoid using too powerful an amplifier in the return link; typically, an amplifier of the solid state type SSPA (Solid State Power Amplifier) amplifying signals at 100 mW such as the WiFi signal amplifiers currently available on the market could be used. It will be noted that conversely in the terminals currently emitting in band S, the fact of using a small omnidirectional antenna entails the use of a high power amplifier (i.e. in the order of 1 W to several W).
The emission/reception installation according to the invention can also have one or more of the following characteristics, considered individually or according to all the technically possible combinations:
The single
The emission/reception installation 1 comprises:
The parabolic reflector 3 receives signals issued from a satellite in band Ku (band 10.7 GHz-12.75 GHz) corresponding to an orbital position at 13° East and from a satellite in band S (band 2170 MHz-2200 MHz) corresponding to an orbital position at 10° East; it will be noted that the information concerning the orbital positions of the satellites and the frequencies used are given purely by way of illustration and in a non-restrictive manner.
The emission/reception unit 2 comprises:
Generally, the modulated signal received by the LNB block 4 has an initial frequency band which extends for example between 10.7 GHz and 12.75 GHz, which corresponds to the Ku frequency band used for the transmission of signals between a satellite and a receiving station on the ground. This band is separated by the LNB block 4 and a low band from 10.7 GHz to 11.7 GHz and a high band from 11.7 GH to 12.75 GHz. Each band, low or high, is divided into frequency channels, the frequency band of each modulated “useful” signal being comprised in one of the frequency channels.
This LNB 4 is, moreover, designed to allow the reception of polarisation signals. The polarisation can be, for example, rectilinear (horizontal or vertical), or else circular (right or left).
For the sake of simplification, the LNB 4 as described below will only deal with a frequency band (for example the band 11.7 GHz to 12.75 GHz) for a single polarisation.
The LNB block 4 incorporates:
The LNB block 4 also comprises an antenna point to transform the wave received according to a polarisation in band Ku into an electrical signal.
The emission/reception block 9 integrates a transmit path TX and a receive path RX.
More specifically, the emission/reception block 9 comprises
The multiplexer 5 comprises:
The installation 1 illustrated in
The box 21 comprises:
The demultiplexer 22 comprises:
The coaxial cable 20 connects the box 21 via its demultiplexer 22 and the emission/reception unit 2 via its multiplexer 15.
The demodulator 24 is for example a demodulator functioning according to the DVB-SH standard (ETSI EN 302 583 v1.1.0 (2008-1) Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for Satellite Services to Handled devices (SH) below 3 GHz, January 2008).
The modulator 25 is for example a modulator functioning according to an asynchronous multiple random access protocol of the type SPREAD ALOHA using interference elimination techniques. Such a protocol is described for example in the document “A High Efficiency Scheme for Quasi-Real-Time Satellite Mobile Messaging Systems” (Riccardo De Gaudenzi and Oscar del Rio—27th AIAA International Communications Satellite Systems Conference ICSSC 2009, Edinburgh, Scotland, 1-4 Jun. 2009).
It will be noted that it is also possible to use other types of protocols (the synchronous protocol DAMA “Demand Assigned Multiple Access” for example) for the modulator 25.
The operating principle of the installation 1 according to the invention rests on the use of a reception part (without emission) in band Ku formed by the reflector 3 and the LNB 2 and by an emission/reception part in band S formed by the emission/reception block 9.
All of the signals are multiplexed on the single coaxial cable 20.
The signals received in band S (here the band [2170 MHz-2200 MHz]) are directly transmitted (without modification of frequency) on the coaxial cable 20 by the multiplexer 15 after filtering via the high-pass filter 16 and passing through the hyperfrequency coupler 19. These signals are then recovered at the level of the hyperfrequency coupler 30 of the demultiplexer 22, then filtered through the high-pass filter 28 before being transmitted to the demodulator DVB-SH 24.
The signals received in band Ku are transmitted by the multiplexer 15 on the coaxial cable 20 after frequency lowering on the first intermediate frequency band (here the band [1100 MHz-2150 MHz]) and filtering through the band-pass filter 17. These signals are then recovered at the level of the hyperfrequency coupler 30 of the demultiplexer 22 then filtered through the band-pass filter 27 before being transmitted to the STB 31 via the output 32.
The signals to be emitted in band S are modulated by the modulator 25 on the second intermediate frequency band (here [370 MHz-400 MHz] given purely by way of illustration) and are transmitted on the coaxial cable 20 by the demultiplexer 22 after having been filtered by the low-pass filter 29. The fact of taking a second intermediate frequency band separate from the first frequency band allows the risks of interference to be avoided between the signals transmitted according to the two intermediate frequency bands. Moreover, the fact of fixing an upper limit less than 450 MHz (here 400 MHz) for the second intermediate frequency band allows the risks of interference to be avoided with the UHF band in the air. The signals to be emitted in band S are for example signals transmitted by a user via the wireless connections 26.
The intermediate frequency bands are, moreover, compatible with the passing band of a standard coaxial cable. It will be noted that an intermediate frequency band is not used for the signals received in band S, the frequency of these latter being directly compatible with the passing band of the cable 20. Even if the installation advantageously uses the band S in emission, the installation according to the invention also allows the use of band S in reception.
The signals received in band Ku are for example television audio/video signals. The installation according to the invention finds a first application of particular interest in the case of interactive television using band S for sending return link messages. Band S allows tens of millions of terminals to be managed in return link sending about one hundred short messages per day.
A second particularly interesting application of the installation according to the invention concerns the field of M2M. In this case, the return link in band S can be used to transmit information originating from an apparatus situated in the house, such as an alarm system; thus, when the alarm system is triggered, a signal is transmitted by the alarm system to the wireless connection means 26 (for example means operating in ZigBee) and a message indicating the actuation of the alarm is transmitted on the return link in band S.
The installation according to the invention can be implemented using an existing installation: thus, it can re-use an existing antenna which is already installed and also the coaxial drop cable, thus limiting considerably the additional costs in terms of equipment and installation.
Of course, the invention is not limited to the embodiment which has just been described.
Thus, the invention has been more particularly described in the case of the band Ku, but it can also be applied to other broadcasting frequency bands such as band Ka.
Likewise, we have described an embodiment specific to the reception of television channels, but the invention can find other applications in the field of M2M; purely by way of illustration, an installation according to the invention can be integrated in street lamps situated on highways; these can then have a surveillance function. For example, all the street lamps which are equipped receive a request (in the first frequency band) asking them to search for a vehicle having a given registration number. Once the vehicle has been identified (by recognition means known to the man skilled in the art) by one of the equipped street lamps, the latter transmits identification information in band S.
It will be noted that the installation according to the invention has been described with wireless connection means, but it can also integrate other types of interface such as an Ethernet or USB connection.
Furthermore, although the invention has been described with reference to the FIGURE for an amplifier of the SSPA type situated after the frequency converter, the invention also applies to an amplifier of the SSPA type, situated before the converter.
Finally, the invention has been presented in the case of a usage in band S, but it can also be used in band C.
Number | Date | Country | Kind |
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09 59574 | Dec 2009 | FR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2010/070380 | 12/21/2010 | WO | 00 | 7/27/2012 |
Publishing Document | Publishing Date | Country | Kind |
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WO2011/076791 | 6/30/2011 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
20060274208 | Pedlow, Jr. | Dec 2006 | A1 |
Number | Date | Country |
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0 825 773 | Feb 1998 | EP |
0 888 690 | Aug 2001 | EP |
2 180 547 | Apr 2010 | EP |
2 901 933 | Dec 2007 | FR |
2 913 285 | Sep 2008 | FR |
Entry |
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International Search Report as issued for PCT/EP2010/070380. |
Number | Date | Country | |
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20120282854 A1 | Nov 2012 | US |