BE1018986A3 - METHOD AND APPARATUS FOR SATELLITE RECEPTION ON A TERRESTRIAL DISTRIBUTION SYSTEM. - Google Patents

Abstract

The satellite reception device on a terrestrial installation comprises: - means (450) for receiving a frequency plan by means of a satellite stream, said frequency plan representing selected frequencies and - means (320,325 ) transposing the selected frequencies to transposed frequencies implemented by said terrestrial installation. In some embodiments, the transposition means is suitable for transposing the selected satellite frequencies to the VHF and UHF band. In some embodiments, the transposition means is adapted not to modify the modulation of the satellite frequencies.

Description

METHOD AND DEVICE FOR SATELLITE RECEPTION ON A SYSTEM

TERRESTRIAL DISTRIBUTION

The present invention relates to a method and a satellite receiving device on a terrestrial distribution facility. It applies, in particular, to the reception and distribution of satellite television signals to a plurality of viewers, for example in collective housing.

it is not possible to directly connect a satellite antenna to an antenna distribution facility for terrestrial television ("TV-TER") for the following reasons: / First, because of incompatibility of frequencies. Indeed, the output frequencies of an LNB (acronym for "Low Noise Block" for low noise block). associated with a satellite dish are between 950 and 2150 MHz. They correspond to the "Satellite Intermediate Band", called "BIS" band. An antenna distribution facility for the TV-TER is designed to carry frequencies between 42 and 852 MHz, corresponding to the VHF and UHF frequency bands (bands I, III, IV and V). The BIS band is therefore located after the TV-TER bands.

2 / Secondly, because the spectral capacity of a terrestrial installation is too limited. In fact, a direct television satellite transmits in two polarizations: vertical and horizontal and the width of the satellite band (Ku) is 2050 MHz. The total spectral capacitance of an orbital position is therefore 2400 MHz (double the 2150-950). However, the spectral capacity of a TV-TER distribution installation is 810 MHz (862-42). It is therefore three times lower than that of an orbital position.

It is therefore not possible to simultaneously transport in a TV-TER distribution installation all the frequencies of the Ku band.

Documents EP 0 915 617 and EP 1 071 286 are known, the teaching of which consists in selecting packets in the incoming flows and transmitted on the channels of the television distribution installation (see paragraph [0008] of document EP 0 91 5 61 7 and Figure 11 of EP 1 071 286). The systems described in these documents implement demultiplexing, re-multiplexing and modulation to retransmit the selected packets (see paragraphs [0016], [0025] and [0026] of EP 0 915 617 and FIG. 11 of EP 1,071,286). They are therefore complex and expensive and do not allow configuration and / or remote updating of the frequencies to be transmitted on a terrestrial installation.

The present invention aims to remedy these disadvantages.

According to a first aspect, the present invention relates to a satellite reception device on a terrestrial installation, characterized in that it comprises: means for receiving a frequency plane via a satellite stream, said plane of frequencies representing selected satellite frequencies and means for transposing the selected frequencies to transposed frequencies implemented by said terrestrial installation.

Thanks to these arrangements, the necessary spectral capacitance is reduced by selecting satellite frequencies. In addition, the transposition makes it possible to move the satellite frequencies in the spectral range (the bandwidth) transported by the terrestrial installation. In addition, the automatic updating of the frequency plan, through the reception of this frequency plan from a satellite, avoids the intervention of technicians on each installation to manually perform this update . This automatic update also prevents viewers from experiencing a break in service or having to memorize a new channel allocation.

According to particular features, the transposition means is adapted to transpose the selected satellite frequencies to the frequency range from 230 MHz to 862 MHz.

This makes the transposed frequencies transportable by an antenna cable already installed. In addition, the disturbances are limited by local transmitters, which are mainly in frequencies below 230 MHz,

According to particular characteristics, the transposition means is adapted to not modify the modulation of the satellite frequencies.

This reduces the complexity of the device while maintaining the demodulation function at satellite digital terminals.

According to particular features, the receiving means is adapted to receive said frequency plan in a satellite broadcast multiplex, to update a frequency plan in memory and to control the transposition means.

According to particular features, the receiving means is adapted to receive the frequency plane identified by a number, said number being modified at each modification of the frequency plan, the update of the stored frequency plan being carried out each time said number is changed.

The update is thus simplified.

According to particular features, the device that is the subject of the present invention, as briefly described above, comprises at least one satellite digital terminal adapted to receive each signal coming from the transposition means, said digital satellite terminal being DVB-S compatible and / or DVB-S2 and equipped with a "broadband" tuner accepting the frequencies of the BIS band ("Intermediate Satellite Band") and / or the frequencies of the UHF and VHF bands.

The broadband used allows the viewer to have a large number of channels and possibly channels broadcast by terrestrial transmitters.

According to particular characteristics, the transposition transposition means comprises, for each frequency represented by the frequency plane - means for selecting at least one polarity of the satellite, vertical or horizontal, - a module for transposing the selected frequency and a bandpass filter whose central frequency is equal to the transposed frequency.

According to particular features, the device that is the subject of the present invention, as succinctly set forth above, comprises an LNB (acronym for "low noise block" for low noise block) quad (providing four quadrans of independent satellite signals) equipping an antenna. parabolic, said quad LNB being connected to the transposition means coupled to a collective antenna.

According to a second aspect, the present invention relates to a method of satellite reception on a terrestrial installation, characterized in that it comprises: a step of receiving a frequency plan by means of a satellite stream, said plane of frequencies representing selected satellite frequencies and a step of transposing the selected frequencies to transposed frequencies implemented by said terrestrial installation.

According to particular characteristics, during the transposition stage, the selected satellite frequencies are transposed to the VHF and UHF band.

According to particular characteristics, at. During the transposition stage, the modulation of the satellite frequencies is not modified.

Since the advantages, aims and particular characteristics of this process are similar to those of the device which is the subject of the present invention, as briefly described above, they are not recalled here.

Other advantages, aims and features of the present invention will emerge from the description which follows, for the purpose of explanation and in no way limiting, with reference to the appended drawings, in which: FIG. 1 represents, schematically, a treatment applied to satellite signals, in a particular embodiment of the method and device of the present invention, Figure 2 shows schematically a particular embodiment of the device object of the present invention, Figure 3 shows, schematically, a means of for selection and transposition of the particular embodiment of the device according to the present invention illustrated in FIG. 2, FIG. 4 schematically represents a part of the particular embodiment of the device that is the subject of the present invention illustrated in FIG. 2 and FIG. represents, in the form of a logic diagram, a particular embodiment of the process object of the present invention.

In FIG. 1, in line from above, different frequency bands allocated to the terrestrial broadcasting of sound and image are observed on an abscissa representing the frequencies between 47 MHz and 2150 MHz. It contains, successively, from left to right: band I, from 47 to 68 MHz, referenced 105, the FM band, from 88 to 108 MHz, referenced 110, band III, from 174 to 230 MHz, referenced 115, bands IV and V, from 470 to 862 MHz, referenced 120, and the BIS band ("Intermediate Satellite Band"), from 950 to 2150 MHz, referenced 125.

The dotted lines indicate that these frequency bands are not represented to scale.

As illustrated by curved arrows; according to the present invention, satellite frequencies which it is desired to distribute are selected and transposed to frequencies of the interval 130 between the bands 115 and 120 and possibly in the bands. 11 5 and 120, or in the interval between the bands 120 and 125 and the band 125. These transposed frequencies are thus made transportable by the antenna cable already installed in a habitat. Preferentially, the modulation is not modified by this transposition.

The interval 130 has, in fact, the interest that the transposed frequencies do not interfere with the frequencies of the other bands III, IV and V. The device which is the subject of the present invention does not then prohibit the distribution installation Antenna also carries FM, UHF and VHF bands.

On the other hand, if each transposed frequency occupies a bandwidth of 40 MHz, only six frequencies can be transposed in the interval 130, whereas one can transpose twenty between 47 and 862 MHz or forty from 230 to 1.030 MHz. . For a bandwidth of 50 MHz, only four frequencies can be transposed in the interval 1, while sixteen can be transposed between 47 and 862 MHz.

It is noted that it is preferable not to use frequencies below 230 MHz because they can easily be disturbed by local transmitters, which reduces to twelve the number of frequencies that are transposed between 230 and 862 MHz with a bandwidth 50 MHz.

As illustrated in FIGS. 2 to 4, the frequency selection and transposition functions are integrated in a "collective transposition module" box 210 which is installed upstream of an antenna distribution installation 215 and downstream of the antenna. a satellite antenna 205 provided with a quad LNB (providing four quadrants of independent satellite signals) 255.

FIGS. 2 also show antennas 220 and 225 for receiving FM radio signals and radio analogue channels, respectively, and a coupler 230 placed upstream of the antenna distribution installation 215 and downstream of the module 210. .

In each place where the visualization of a television channel is desired, here the living rooms of two apartments 245 and 250, a digital terminal (in English "set-top box", also improperly called "decoder") satellite 235 is connected to the antenna distribution facility 215 and to a television 240.

The digital terminal 235 is a digital "satellite" terminal compatible DVB-S and / or DVB-S2, equipped with a "broadband" tuner that accepts frequencies of the BIS band and the frequencies of the UHF and VHF bands. Compared with the digital satellite terminals of the prior art, the modification of this digital terminal is limited to the change of the tuner. For example, it is possible to rely on an existing digital terminal Dual-S (registered trademark). The software is adapted to allow reception of all frequencies.

As seen in FIGS. 3 and 4, the frequency transposition is performed by a "transposition module" 210 which integrates the following means: a switch or means 315 for selecting the polarity of the satellite (vertical or horizontal) originating from two antenna outputs 305 and 310, a frequency transposition means 320, preferably from the Ku band to the VHF or UHF bands, associated with a variable frequency local oscillator 325 and a channel filtering means 330 by a band-pass filter, the center frequency will be equal to the output frequency. For example, the bandwidth of the filter is 40 MHz.

FIG. 4 shows a device adapted to transpose six frequencies or "multiplex". As explained above, depending on whether one wishes to occupy only the interval 130 or the interval 1 and the band 120 and depending on whether the bandwidth used is 40 or 50 MHz, the device comprises, in fact, between four and twelve selection means 315, transposition 320, and filtering 330. As has been seen above, these examples are not limiting.

FIG. 4 shows an input 405 of signals from the quad LNB 255, that is to say signals from four quadrants of satellites corresponding to the four combinations of horizontal and vertical polarizations and of high and low positions.

The input 405 is connected to a power injector 410, itself connected to a band selector 415 which comprises, for each transposition means 320, a switch 315 connected, as input, to the four signals coming from the quad LNB 255 and , at the output, to this transposition means 320. Each transposition means 320 is associated with variable frequency local oscillator 325 and with a bandpass filter 330. The outputs of the bandpass filters 330 are connected to inputs of a coupler 435 which optionally also receives FM antenna 220 and analog television 225 signals (see Figure 2).

At the output of the coupler 435, an amplifier 440 amplifies the signals and supplies the output signals to an output 445 connected to the antenna distribution installation 21 5.

The signals conveyed by the band selector 415 are also supplied to a satellite signal output 470 intended to be connected to another installation, for example of the switched BIS type.

Furthermore, a control module, or "chipset", 450 is connected to a switch 475 similar to the switches 315. This control module 450 comprises: a DVB S or DVB S2 decoder, or "front-end" satellite, 455 which extracts satellite signals, a lookup table associated with a table number, or a table index and a control module 460, which determines whether the table number has changed and, if so, who saves the new table. correspondence 480.

The control module 460 is, for example, consists of a microprocessor based on a "back-end" of digital terminal.

The control module 460 communicates with the digital terminals 235 via an interface 465. The purpose of this interface .465 is to make it possible to program the output frequencies of the modulators or to introduce a table selection to download when installing the system. With the initial correspondence table then updated by satellite download, the control module 460 also controls the frequency of the local oscillators 325.

Thus, updating the correspondence table, also called "frequency plan" is automatic. In case of modification of the satellite frequency plan, the system is automatically adjusted without local intervention by a technician and without interruption of service.

The correspondence table, broadcast in a multiplex which is continuously received by the control channel, has a dual use: at the time of installation, the technician selects a service plan which will be loaded automatically.

during use, the control channel continually determines whether the number of the table changes, for example increments. When incrementing, the service plan is loaded automatically and the satellite frequency plan is updated.

With regard to co-channel interference, the number of modules, of transposition depends on the number of satellite transponders that it is desired to carry simultaneously. If the frequencies used at the output of the transposition modules correspond to the UHF bands IV and V, it is useful, in order to avoid Cocanal interference, to take some precautions: - the terrestrial TV antennas will be dismantled, - if an FM antenna is connected and must remain so, a band-pass filter (88-108 MHz) is installed before the coupler to eliminate the residues of the UHF band, - the antenna distribution facility must be properly shielded and - the output level of the amplifier is set at -20 dB at the input of the collective distribution system, for satellite multiplexes.

This will keep a sufficient C / N ratio, greater than 8 dB. The value of N is constituted by the sum of the noise present at the output of the antenna amplifier and the co-channel noise, which can be received because of insufficient shielding.

It is observed that, in addition to the elements illustrated in FIG. 4, it is also possible to connect a switched BIS installation to the parabola 205 by a bypass. This switched BIS band makes it possible to offer a satellite television offer in addition to a digital terrestrial television offer carried by satellite transponders.

For the reception of the channels of the DTT offer by satellite, these will be grouped on a minimum of transponders.

As seen in FIG. 5, the method that is the subject of the present invention comprises a step 505 for installing the device that is the subject of the present invention and, if applicable, a broadband tuner in the digital terminals.

Then, during a step 510, we receive from a satellite, a table of correspondence, or frequency plan associated with a number.

During a step 515, it is determined whether the number received is identical to the last number received. If yes, we go to a step 525. If no, during a step 520, we update the correspondence table maintained by the digital terminals and assign a frequency to each local oscillator.

In step 525, satellite oscillator frequencies are selected via local oscillators!

In step 530, the selected frequencies are transposed to a target frequency range without modification of the modulation.

During a step 535, the transposed signals are transmitted to the digital terminals. Then we return to step 510.

Claims (10)

1. Satellite reception device on a terrestrial installation (215), characterized in that it comprises: means (450) for receiving a frequency plan via a satellite stream, said frequency plan representing selected satellite frequencies and means (320, 325) for transposing the selected frequencies to transposed frequencies implemented by said terrestrial facility. / .2 - Device according to claim 1, characterized in that the means (320, 325) of transposition is adapted to transpose the selected satellite frequencies to the range (Ί 20, 1 30) of frequencies from 230 MHz to 862 MHz . 3. Device according to any one of claims 1 or 2, characterized in that the means (320, 325) of transposition is adapted not to change the modulation of satellite frequencies. 4. Device according to any one of claims 1 to 3, characterized in that the receiving means (450) is adapted to receive said frequency plan in a multiplex broadcast by satellite, to update a frequency plan in memory (480) and controlling the transposing means (320, 325). 5. Device according to claim 4, characterized in that the receiving means (450) is adapted to receive the frequency plane identified by a number, said number being modified at each modification of the frequency plan, updating the plan. of stored frequencies being performed each time said number is changed. 6. Device according to any one of claims 1 to 5, characterized in that it comprises at least one digital satellite terminal (235) adapted to receive each signal from the means (320, 325) of transposition, said digital satellite terminal being DVB-S and / or DVB-S2 compatible and equipped with a broadband tuner that accepts BIS ("Intermediate Satellite Band") frequencies and / or UHF and VHF band frequencies. 7. Device according to any one of claims 1 to 6, characterized in that the means (320, 325) of transposition comprises, for each frequency represented by the frequency plan: - means (315) for selecting from least one polarity of the satellite, vertical or horizontal, - a module (320, 325) of transposition of the selected frequency and - a bandpass filter (330) whose central frequency is equal to the transposed frequency. 8. Device according to any one of claims 1 to 7, characterized in that it comprises an LNB (acronym for "low noise block" for low noise block) quad (providing four quadrants of independent satellite signals) (255) equipping a satellite dish, said quad LNB being connected to the transposition means coupled to a collective antenna. 9. A method of satellite reception on a terrestrial installation, characterized in that it comprises: a step (510) for receiving a frequency plan via a satellite stream, said frequency plan representing selected satellite frequencies and a step (530) for transposing the selected frequencies to transposed frequencies implemented by said terrestrial installation. 10. The method of claim 9, characterized in that, during the step (530) of transposition does not change the modulation of satellite frequencies.