EP3075086A1

EP3075086A1 - Method and system for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, and related transmitter, receiver system, transmodulator and receiver

Info

Publication number: EP3075086A1
Application number: EP13796046.4A
Authority: EP
Inventors: Robert James
Original assignee: Saronikos Trading and Services Unipessoal Ltda
Current assignee: Saronikos Trading and Services Unipessoal Ltda
Priority date: 2013-11-25
Filing date: 2013-11-25
Publication date: 2016-10-05
Also published as: WO2015074728A1; CN105765888B; CN105765888A

Abstract

A method is described for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, said radiotelevision signals comprising a plurality of radiotelevision programs or services receivable by a receiver in a certain frequency band, wherein at least a portion of said frequency band has been discontinued for the radiotelevision signals of the terrestrial digital broadcasting type and assigned to a different service, in particular to a mobile telephony service, such as the LTE type, wherein it is provided to transmit satellite type radiotelevision signals containing said receivable radiotelevision programs or services from which radiotelevision signals of the terrestrial digital broadcasting type are derived that are placed in channels belonging to said portion of said frequency band, said radiotelevision signals of the terrestrial digital broadcasting type not being irradiated, but conveyed via cable to said receiver.

Description

METHOD AND SYSTEM FOR THE TRANSMISSION AND RECEPTION OF RADIOTELEVISION SIGNALS OF THE TERRESTRIAL DIGITAL BROADCASTING TYPE, AND RELATED TRANSMITTER, RECEIVER SYSTEM, TRANSMODULATOR AND RECEIVER

DESCRIPTION

The present invention relates to the field of methods for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type and relative apparatus.

With reference to Figure 1, the reception and subsequent distribution of terrestrial and satellite broadcasted television channels up to now has been carried out by individual or communal type coaxial cable systems 1 ', using the same radio frequency channels with which radiotelevision signals are broadcasted (terrestrial broadcasting, VHF and UHF bands) or by converting radiotelevision signals received by satellite from the 11-12 GHz band, in the band of the first intermediate frequency l^stIF to 950-2150 MHz, within which they can be distributed via cable without excessive attenuation.

More in particular, satellite type radiotelevision signals are received by a satellite antenna 2' associated with a Low Noise Block converter 3', or LNB, which moves in block the satellite radiotelevision signals to the first intermediate frequency l^stIF, while the broadcasted terrestrial radiotelevision signals are received by an antenna 4' enabled to receive such signals that are then passed on to a terminal head 5' for terrestrial television channels.

The satellite and terrestrial radiotelevision signals are then sent, by way of a coaxial cable distribution network, to user's plug sockets connected to apparatus having a tuner for terrestrial broadcast bands (TV with integrated digital tuner or iDTV: "integrated Digital Television") or by means of a dedicated set-top box, that tunes and demodulates television channels (terrestrial and satellite) according to their radiofrequency and modulation characteristics. It is appropriate here to take note that the reception by the individual user in an apartment building requires the use of suitable equipment, so- called multi-switch, to be installed for example in relation to the apartment building's floor-plan, upstream from the user's set-top box for tuning, demodulating and decoding the satellite signals. Television receivers, set-top boxes and iDTVs, are usually able to receive broadcasted terrestrial television signals (DVB-T/T2); the frequency bands from which they are able to tune are those shown in Figure 2, as determined nationally and internationally by competent bodies and authorities.

With reference to Figure 3 an additional example of a system 1 for receiving broadcasted terrestrial and satellite radiotelevision signals is illustrated whose main characteristic is to make available to the user's plug sockets all television channels, namely digital terrestrial broadcasts (DVB-T) and satellite channels (DVB -S), in the abovementioned VHF/UHF bands and with the COFDM modulation ("Coded Orthogonal Frequency - Division Multiplexing") typical of DVB-T (Digital Video Broadcasting-Terrestrial) .

In fact, the radiotelevision signals received by the satellite antenna 2 with QPSK modulation, are conveyed to the low noise converter 3 and then trans-modulated, in the terminal head 7 for satellite television channels, in the COFDM format typical of DVB - T, before being sent to the distribution network of the communal television system together with other terrestrial television broadcasted signals.

This distribution technique is only feasible if the terrestrial broadcasts do not occupy all the available channels of the VHF/UHF bands, but leave an adequate number free. This requirement was, until recently, impossible to fulfill in some countries, where the occupation of the VHF/UHF bands by national and private television broadcasters, was almost total.

It has recently been established that the V Band (UHF) should be limited to 790 MHz, corresponding to the UHF channel 60, eliminating the digital terrestrial television service from 791 MHz to 862 MHz (800 MHz) and assigning said frequencies to the LTE type mobile phone service, as represented in Figure 4. Therefore the frequencies from 791 MHz to 862 MHz are no longer part of the spectrum reserved for digital video broadcasting terrestrial (DVB -T) and it is therefore no longer possible to radiate television services in this frequency band, because such services would be dominated by the mobile telephone signals (LTE), which, given their extensive transmission system in both rural and urban areas, cause a high level LTE signals received by the television antenna with respect to signals coming from a transmitter of digital terrestrial broadcasts. However, television signal receivers related to digital terrestrial broadcasting (DVB -T) still have the ability to tune and demodulate television signals related to digital terrestrial broadcasting (DVB -T) in the frequency band from 7 1 MHz to 862 MHz. This could continue for many years since the frequencies now assigned to the LTE service in certain countries are frequencies that, according to the ITU World Standard, have always been reserved for broadcasting of radiotelevision signals, and it is not certain that all countries will discontinue some frequencies in favor of mobile services. Therefore the manufacturers of television receivers will continue to produce apparatus capable of receiving terrestrial television signals, also in the television bands that in some countries may have already been discontinued.

It is also possible that in the future the upper limit of available bandwidth for terrestrial television broadcasting will be further reduced, eliminating the 700 MHz band.

Therefore, even today, UHF channels 61-69 have been discontinued from terrestrial television broadcasting, which make up the 800 MHz band, i.e. nine radiofrequency channels of 8 MHz bandwidth. In the future the UHF channels 49-60 will also be deleted, which are the 700 MHz band, that is, twelve additional radiofrequency channels of 8 MHz bandwidth. Also in this case television signal receivers related to digital television broadcasting - terrestrial (DVB-T) will for many years be able to tune and demodulate television signals related to digital terrestrial broadcasting (DVB-T).

This reduction in the number of radio frequency channels available for terrestrial television broadcasting will significantly restrict the amount of television programs receivable by users with this service. Since each terrestrial broadcasted TV channel with digital coding and modulation (DVB -T) contains at least six SD (standard definition) coded television programs (coordinated in a group called MUX or Multiplex DVB), the deletion of nine channels (current) and a further twelve (in the future), for a total of twenty one television channels, corresponds to the inability to transmit up to about one hundred and twenty different television programs.

An object of the present invention is therefore to indicate a method and a system for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, and relative apparatus, that solves the drawbacks due to assignment to mobile telephony services of a band previously assigned to terrestrial digital broadcasting. A further object of the present invention is to indicate a method and a system for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, and relative apparatus, which allows to maintain the number of radiotelevision programs, that can be received by a television signal receiver of digital terrestrial broadcasts of the known kind, unchanged.

A further object of the present invention is to indicate a method and a system for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, and relative apparatus, which does not require the replacement of the antenna system used for receiving said radiotelevision signals, but simply adapt and modify it.

A further object of the present invention is to indicate a method and a system for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, and relative apparatus, that does not need to modify or replace the receiver of said radiotelevision signals, in order to make use of the number of television services equal in number to those received before part of the spectrum relative to digital terrestrial broadcasting was assigned to mobile operators.

A further object of the present invention is to indicate a method and a system for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, and related apparatus, which allows to allocate in a predetermined manner, by a broadcaster or by a user, the radiotelevision programs in the frequency band allocated to mobile services.

A further object of the present invention is to indicate a method and a system for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, and related apparatus, which allows for increasing the coverage of the radiotelevision signals of the terrestrial digital broadcasting type receivable by a receiver of the known kind.

A further object of the present invention is to indicate a method and a system for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, and related apparatus, which complies with the standards relating to the use of frequencies and which does not require authorization from the authorities in charge of the allocation of broadcast frequencies for both television and telephone. The invention also relates to a reception system, a transmitter and a receiver of radiotelevision signals of the terrestrial digital broadcasting type and a trans-modulator used in said reception system.

In summary, in order to limit the effects of the drastic reduction of radiofrequency bands dedicated to terrestrial television broadcasting, the method and system of the present invention provides for transmitting radiotelevision programs, which can no longer find a location in the channels of the terrestrial broadcasted television, by means of satellite television transponders, for example in the 11-12 GHz band, to receive them in the television antenna system 1 illustrated in Figure 3, subsequently to convert them into the COFDM format and then distribute them in the radiofrequency channels that are certainly available, as they are no longer used for terrestrial television broadcasting, but assigned to the LTE mobile service, i.e. in the channels of the 800 MHz band (UHF channels 61-69) and in the future in the channels of the 700 MHz band (UHF channels 49-60).

This opportunity is certainly feasible using the type of signal distribution system as illustrated in Figure 3, since the interference problems due to the LTE service in such frequency bands are resolved and guaranteed by the efficiency of the shielding of the cables and equipment that must meet the standards in force (EN 50083-2).

In fact, these rules allow for adequate immunity to electromagnetic fields due to the LTE service operating in these frequency bands.

The method and system, and related apparatus, of the present invention therefore allow to use the television channels discontinued for use by the terrestrial television broadcasting (61-69 UHF today and in the future 49-60 UHF) for the distribution via cable in an individual or Community distribution system (master antenna system), as these signals are transmitted in the DVB-T standard (COFDM modulation), receivable by normal digital TV receivers (iDTV and set-top boxes for DTT: Digital Terrestrial Television), or in the DVB-T2 standard, planned for future television receivers and set- top boxes for DTT.

The allocation of television programs received by satellite and inserted today in the UHF channels 61-69 can be carried out in a predetermined or different manner in each individual or Community cable distribution system.

It is important to note that this technique achieves: a) practically a 100% national coverage (being carried out by satellite), not possible with a national terrestrial distribution network, which never has a total coverage;

b) that UHF channels 61-69, and in the future also the UHF channels 49-60, no longer have to be assigned by a body or a national authority, but are usable, as appropriate, for any situation of a television reception system, being used freely in a cable distribution system and not suffering interference by the LTE service. As previously explained, the guarantee of non-interference is provided for example by the requirements of the Standard EN 50083-2, effective and mandatory in Europe for equipment installed in cable distribution systems. Even the coaxial cable itself must provide a guarantee of adequate shielding: the requirement of shielding effectiveness of at least 75 dB (Class A), obtainable with good quality coaxial cables in the frequency band 700-800 MHz, is considered sufficient by the current Standards.

Furthermore, the use of trans-modulators that only work in the 800 MHz band (in the future also in that of 700 MHz) and, possibly, with a prearranged allocation of television channels, allows for obtaining a cost reduction of the apparatus, resulting in a simplification of its circuitry and functioning.

Further characteristics of the invention are object of the annexed claims which are considered an integral part of the present description.

The above objects will become more apparent from the detailed description of the method and system, and relative apparatus, according to the present invention, with particular reference to the accompanying figures in which:

- Figure 1 shows a diagram of a reception system of terrestrial and satellite radiotelevision signals of the known type;

- Figure 2 illustrates a table of frequency bands on which a receiver of terrestrial broadcasted television signals is able to carry out the tuning;

- Figure 3 illustrates a block diagram of a reception system of terrestrial and satellite radiotelevision signals used in the method and in the receiving system according to the present invention;

- Figure 4 shows the band usage of the LTE type mobile service;

- Figures 5 and 6 show respective block diagrams of two respective embodiments of a trans-modulator of the radiotelevision signals receiving system of Figure 3. The technical description and installations of the proposed inventive solution is clear from the operational description of the distribution technique via coaxial cable as shown in Figure 3, bearing in mind that the channels in which the radiotelevision programs received by satellite are distributed are those of the 800 MHz band (and in the future those of the 700 MHz band) assigned to the LTE service.

For example, with the current situation of channels previously assigned to terrestrial television broadcasting that are no longer in use, it would be possible to transmit via satellite, in the bands 11-12 GHz allocated to such service, nine different groups of television programs (multiplex or MUX) and, after their reception in the antenna system 1, convert each of them to the band of the first intermediate frequency l^stIF (with QPSK modulation if DVB-S or even 8-PSK if DVB-S2) in the UHF channels 61-69 (with COFDM modulation typical of DVB-T or DVB-T2). This operation can be performed by the apparatus shown in Figure 3, where each trans-modulator 9 of the terminal head 7 for satellite television channels is made up of:

- a tuner 20 in the band of the first intermediate frequency 1^STF of one of the television channels broadcast by satellite;

- blocks 21, 22, 23, 24 (see Figure 5) which convert the tuned satellite radiotelevision signal from QPSK modulation (if DVB-S or even 8-PSK if DVB-S2) to the COFDM modulation (DVB-T or DVB-T2);

- a subsequent frequency converter 25 able to obtain an output signal from the trans- modulator 9 in one of the television channels (8 MHz wide) comprised between channel 61, having a center frequency of 794 MHz, and channel 69, having a center frequency of 858 MHz, or in the future comprised between channel 49 and channel 69.

Since television receivers (iDTV and set-top boxes) capable of receiving the entire UHF band (up to channel 69) are still on the market, the user will be able to receive radiotelevision programs broadcast by satellite, but converted (both in frequency and modulation) in the channels, for example today 61-69 UHF, with COFDM modulation. A detailed description of the functions of the trans-modulator 9 is given in the following with particular reference to Figure 5.

The functional operations, carried out on the radiotelevision signal received by satellite in the 11/12 GHz band and converted in the low noise converter 3 of the antenna (parabolic) in the first intermediate frequency band (950-2150 MHz), are the following: 1) tune the received signal in the first intermediate frequency band by way of the tuner 20;

2) demodulate the output signal from the tuner 20 by a QPSK demodulator 21 if the signal is compliant with the DVB-S standard, or via a demodulator QPSK or 8-PSK if the received signal is compliant with the DVB-S2 standard;

3) decode by way of a decoder block 22, the output signal from the demodulator 21 with respect to channel coding (Viterbi if the satellite signal is compliant with the DVB-S standard or LDPC if the satellite signal is compliant with the DVB-S2 standard) used in the satellite transmission, Reed-Solomon decoding (if the satellite signal is compliant with the DVB-S standard) or BCH (if the satellite signal is compliant with the DVB-S2 standard), and "descrambling" the related data, in order to obtain a complete multiplex, transmitted by satellite;

4) extract in a first part of an extraction block 23 the components that make up the multiplex to identify each TV program (video, audio and data) by way of information contained within the multiplex (more precisely in the SI/PSI tables) obtaining the values of the PID (Packet Identifier) assigned to the multiplex transmitted by satellite to every component of the television programs (video, audio and data) that a user may wish to receive; reassembling, in a second part of the extraction block 23, the multiplex, possibly smaller than that received, for example, only using the radiotelevision programs of interest to the user, in particular the most important, at a national television broadcasting level, and that can be included in the transmission capacity with CODFM modulation of the DVB-T channel (or DVB-T2);

5) encode, in an encoder block 24, according to the COFDM format, the new reassembled multiplex;

6) convert in frequency, in a frequency conversion block 25, the output signal from the encoder block 24 with COFDM encoding in one of the channels 61-69 UHF (or in the future 49-69 UHF).

The proposed solution is advantageous inasmuch:

- allows for increasing the number of television channels distributed in an antenna installation, compared to those broadcast today with digital terrestrial broadcasting (DVB -T), enabling reception with normal television receivers which users already own; - the blocks 20,21,22,23,24,25, used for the trans-modulation from QPSK, if the signal is compliant with the DVB-S standard, or QPSK or 8-PSK if the received signal is compliant to the DVB-S2 standard, to COFDM of DVB-T/T2, may be simplified by reducing overall costs, having to generate the signals only in the 800 MHz band (and in the future the 700 MHz band);

- no authorization is required for the use of UHF channels 61-69 (UHF channels 49-69 in the future), by the competent authorities, as these channels are used only in private antenna distribution installations (domestic systems);

- positioning radiotelevision programs within the MUX contained in the UHF channels 61-69 (or in the future UHF 49-69) can be chosen either in a preset mode or at will, even on the basis of priority criteria established by the user; channel allocation is in fact established during the installation of the system by a technician, that takes into account the preferences of the user, or by the broadcaster, if the method described below is used;

- makes it possible to place the preferred television services of the user in a single multiplex, facilitating and reducing the time of switching from one program to another

(zapping). In fact, if zapping is carried out from one television service to the next, or to the previous one, in the case of two services contained in the same television multiplex, the switching time between one service and the other is less if compared to the case in which the two services are contained in two different multiplexes.

The method according to the present invention provides the advantage, compared to known solutions, of simplifying the tuners 20 of the trans-modulators 9, nowadays adapted to generate the UHF channels 61-69, or in the future UHF channels 49-69, thus resulting in a cost reduction of the trans-modulators 9.

In a first further embodiment of the transmission method of radiotelevision signals according to the present invention, in order to simplify the operations to be carried out in trans-modulators 9 shown in Figures 3 and 5, it can be assumed to transmit by satellite with QPSK modulation, or 8-PSK if compliant to the standard DVB-S2, a multiplex already divided or easily divisible into two parts. In fact, the transmission capacity of a DVB-T channel of 8 MHz with COFDM modulation is, at most, of the order of 30 Mbit/s (see Table A.l of ETSI EN 300 744 Standard v.1.5.1 (2004-11), p. 40), which is about half of that of a satellite transponder, that with QPSK modulation is capable of transmitting 27,5 Msymbol/s, that is 55 Mbit/s. This first further embodiment involves:

- in transmission, the use of a statistical satellite multiplex that works in a particular way, i.e. it keeps constant over time the bit-rate of each of the two parts of the multiplex (semi-multiplex A and semi-multiplex B), and not only the multiplex as a whole. Use of a normal multiplex (non-statistical) simplifies the transmission system, but does not allow to optimally exploit the available bandwidth;

- in reception, the use of two trans-modulators 9 (or a single trans-modulator 9' with two outputs as shown in Figure 6) that trans-modulate on two distinct channels (from among those always available: 61-69 UHF or in the future 49-69 UHF) the two parts of the multiplex received by satellite, assigning user definable preset channels, or programmable by a computer product that can be uploaded to a memory of said trans- modulators 9 that include, in the block 23 of Figure 5, portions of software code, as it will be further explained below.

In a second further embodiment of the transmission method of radiotelevision signals according to the present invention, it is possible to transmit by satellite a multiplex with a band approximately half that compared with the usual DVB-S or DVB-S2 standards, so as to be QPSK demodulated (if DVB-S) or QPSK/8-PS (if DVB-S2) and COFDM re-modulated, without requiring processing by the trans-modulator 9 of Figures 3 and 5, further reducing the complexity and costs. This solution is easy to implement, but penalizes the transmission capacity of the satellite.

In a third further embodiment of the transmission method of radiotelevision signals according to the present invention, it is possible to introduce into a suitable section of a multiplex, information which, via a software program product that can be uploaded to a memory of said trans-modulator 9 and comprising portions of software code 23 in block 9 of the trans-modulator of Figure 5 which can possibly be updated via satellite, allows for the automatic assignment of UHF channels 61-69 or UHF channels 49-69 in the future, re-modulated into COFDM format, taking into account the priority (importance) of the programs broadcast by satellite in QPSK format (or 8-PSK if DVB-S2).

This solution involves a further advantage for simplifying the work of the antenna installation technician, avoiding the need, in the installation phase of trans-modulators 9, to manually define the output channel. Given that, nowadays, labor costs impact the overall cost of the installation more than the cost of the apparatus itself, it would be advantageous if it was the actual broadcaster to decide on which terrestrial television channel the various services of the multiplex (a group of radiotelevision programs) should be included.

For instance, since there are broadcasters that carry dozens of services that cannot be assigned to a single multiplex, each of these broadcasters could allocate all of their services in contiguous multiplexes. Or such assignment of channels could be made by means of appropriate national (or international) agreements. In this case, the broadcaster would insert such information, namely that of the channel on which to perform the trans-modulation, in one of the SI/PSI tables present in the multiplex, the trans- modulator 9 would read the information in the appropriate table and would then automatically execute the tuning.

It is to be noted that the SI tables (Service Information), which is defined by the DVB, and PSI (Program Specific Information), defined by MPEG, are a set of digital information that describe the transmission channel, where the services have to be transmitted and its contents: the related specification is the ETSI EN 300 468. In the DVB terminology a service is a television network (e.g. ARD), while, in MPEG terminology, a television network is referred to as a program.

In order to describe in greater detail the third further embodiment proposed herein, the two cases (previously referred to as second and first further embodiment of the transmission method) are once again referred to:

a) in the second further embodiment, a multiplex transmitted by satellite is transferred entirely on a terrestrial channel: in this case there would be however an inefficient usage of satellite bandwidth, as the satellite multiplex has about double the capacity and that used would only be that necessary for performing the direct trans-modulation of the multiplex format from QPSK if the received signal is compliant with the DVB-S standard (QPSK or 8-PSK if the received signal is compliant to the DVB-S2 standard) to the COFDM format of the DVB-T channel (or DVB-T2);

b) in the first further embodiment, the services present in the satellite multiplex are distributed on two or more terrestrial channels chosen among those that have been discontinued.

In the first hypothesis, the coincidence of bandwidth between satellite and terrestrial multiplexes (case a), reference can be made to the document entitled ETSI TR 101 211: "Digital Video Broadcasting (DVB) Guidelines on implementation and usage of Service Information (SI)". This document already refers to the example of satellite services that are transferred to cable networks or fixed antenna installations. When this takes place, the NIT table (Network Information Table) of the satellite passes through the cable, i.e. the table that describes the characteristics of the satellite channel in which the multiplex is located. It may therefore occur that a cable or terrestrial decoder (in the case of master antenna installations) receives a NIT table relative to the satellite channel, and in this case said decoder should ignore said table, however current decoders do not do this, or in cases where they do, a malfunction of the actual decoders would result.

According to the embodiment that is proposed herein, it is contemplated to insert in the satellite multiplex, not only the NIT table relating to said multiplex, but also the NIT table with the specifications of the terrestrial channel (DVB-T/T2) upon which the signal must be transferred, i.e. the specifications of a channel belonging to a network located downstream, rather than upstream. This situation is not provided for in the cited document: according to the present invention, a satellite decoder would ignore the NIT table relative to the terrestrial channel, while a terrestrial decoder would ignore the NIT table relative to the satellite multiplex.

Therefore, without changing in any way the specific SI/PSI, it is possible to convey to the trans-modulators 9 the information needed to automatically tune in to the decommissioned terrestrial channel and chosen by the broadcaster.

In the second example (case b) only a part of the services (TV programs) in the satellite channel would be placed on a decommissioned terrestrial channel, while other services are assigned to another decommissioned terrestrial channel (either in UHF channels 61- 69 or in the future UHF 49-69). In this case, the target terrestrial channel must be service to service defined. The situation can be solved in a similar way to which the problem of transmitting the LCN numbers ("Logical Channel Number") associated with each service was solved. In practice, in the NIT table of the satellite multiplex a descriptor indicating, for each service, or radiotelevision program, the LCN associated with it can be inserted. Such a descriptor was not provided for by MPEG nor by DVB: however it is possible, taking advantage of the flexibility of the specific SI/PSI, to add such a descriptor in the NIT table of the satellite multiplex, in the form of descriptor defined by the user ("user defined"). According to the present invention, a similar device could be made to specify the destination channel of each service, using another "user defined" descriptor. This descriptor would be ignored by all decoders, and would be used exclusively by the trans-modulator 9 to learn about the target channel with all the services of the multiplex.

With reference to Figure 6, a further way to solve the case (b) may be the following. Rather than adding a new descriptor to the satellite NIT table, the satellite broadcaster could also provide, in addition to the usual satellite NIT table, this time without any modifications, the two NIT tables related to the two decommissioned digital terrestrial channels to which the various services in the multiplex satellite would be transferred (based on the idea described above for case (a): transmission of NIT tables of networks located downstream). In other words, there would be a NIT table A relating to the semi- multiplex A, and a NIT table B relative to the semi-multiplex B. Each table containing data on the digital terrestrial channel on which it is placed within the semi- multiplex, and a list of LCN. The satellite decoder would ignore both tables, as they refer to non- congruent networks; however said tables would be used by a trans-modulator 9' with double output that works, according to the present invention, in a coordinated manner: one part identifies the services of the semi-multiplex A, encodes them into a COFDM format in block 24a and converts them, through block 25a, in the digital terrestrial channel indicated by the NIT table A, whereas the other part identifies the services of the semi-multiplex B, encodes them in the COFDM format in block 24b and converts them through block 25b, in the digital terrestrial channel indicated by the NIT table B. The same operation could be performed by two distinct trans-modulators, i.e. not of the double output type, however in this case the first trans-modulator 9 would have to cancel the NIT table B, while the second trans-modulator 9 would have to cancel the NIT table A, so that each digital terrestrial channel only contains the NIT table relating to it so as not to confuse the decoder DVB-T/T2 located downstream.

Similar to the trans-modulator 9, the trans-modulator 9' also comprises a memory in which a software program product can be uploaded comprising software code portions in the block 23.

There are numerous possible variants to the method and system for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, and related transmitter, receiver system, trans-modulator and receiver described as an example, without for this departing from the principles of novelty inherent in the inventive idea, as it is also clear that in its practical forms of implementation the illustrated details may be different, and the same may be replaced with technically equivalent elements.

For example, to provide the trans-modulator 9, 9' with the information necessary for relocating the various services (TV programs) in the frequency band of the channels (UHF 61-69 or in the future UHF 49-69) of broadcasted terrestrial television, there are other possible solutions, taking advantage of other tables also belonging to the SI/PSI family of tables.

For example, it is possible to use the SDT table ("Service Description Table"), or the PAT table ("Program Association Table"), introducing new descriptors.

Therefore it is easily understandable that the present invention is not limited to a method and system for the transmission and reception of radiotelevision signals of the terrestrial digital broadcasting type, and related transmitter, receiver system, trans- modulator and receiver, but is subject to various modifications, improvements, substitution of equivalent parts and elements without however departing from the inventive idea, as is better clarified in the following claims.

Claims

1. Method for the transmission of radiotelevision signals of the terrestrial digital broadcasting type, said radiotelevision signals comprising a plurality of radiotelevision programs or services receivable by a receiver in a certain frequency band, wherein at least a portion of said frequency band has been discontinued for the radiotelevision signals of the terrestrial digital broadcasting type and assigned to a different service, in particular to a mobile telephony service, such as the LTE type, wherein it is provided to transmit satellite type radiotelevision signals containing said receivable radiotelevision programs or services from which radiotelevision signals of the terrestrial digital broadcasting type are derived that are placed in channels belonging to said portion of said frequency band, said radiotelevision signals of the terrestrial digital broadcasting type not being irradiated, but conveyed via cable to said receiver.

2. Method according to claim 1, comprising the steps of:

- receiving satellite type radiotelevision signals containing said receivable programs or services;

- trans-modulating such satellite type radiotelevision signals containing said programs or services receivable by way of a trans-modulator (9) that decodes said satellite type radiotelevision signals and re-encodes them as radiotelevision signals with appropriate modulation to be decoded by television signal receivers of digital terrestrial broadcasting, in particular with COFDM modulation (DVB-T or DVB -T2);

- converting in frequency said radiotelevision signals with appropriate modulation, in particular COFDM (DVB-T or DVB-T2), only in the radiotelevision channels belonging to said at least a portion of said frequency band (800 MHz, 700 MHz) and, eventually, with a preset allocation of television channels within said portion.

3. Method according to claim 2, wherein the allocation of said radiotelevision signals with said appropriate modulation, in particular COFDM (DVB-T or DVB-T2), in a radiotelevision channel of said at least a portion of said frequency band is determined by a user of said receiver.

4. Method according to claim 1, wherein said satellite type radiotelevision signals comprise a multiplex, described by a Program Specific Information type table, or a Service Information type, in which a descriptor is inserted for specifying, for each of said receivable programs or services, a target channel contained in said at least a portion of said frequency band.

5. Method according to claim 1, wherein said satellite type radiotelevision signals comprise a multiplex, described by a Program Specific Information (PSI) type table or Service Information (SI) type, which is divided into a first semi-multiplex (A) and into a second semi-multiplex (B), each of said semi-multiplexes (A, B) being intended for a respective target channel contained in said at least a portion of said frequency band, and wherein within said table a descriptor is inserted containing information able to specify, for each of said receivable programs or television services, the respective target channel.

6. Method according to claim 5, wherein a second descriptor is inserted in said table able to specify the logical channel number (LCN), associated to each of said receivable programs or television services.

7. Method according to one or more of the claims from 4 to 6, wherein said table is a Network Information Table (NIT) table, or a Service Description Table (SDT), or a Program Association Table (PAT).

8. Method according to claim 1, wherein said satellite type radiotelevision signals comprise a multiplex, described by a first Network Information Table (NIT) type table, which is divided into a first semi-multiplex (A) and in a second semi-multiplex (B), and in which is inserted in said first semi-multiplex (A) a second Network Information Table (NIT) type table able to specify, for the radiotelevision programs or services of said first semi-multiplex (A), a target channel contained in said at least a portion of said frequency band and, for each of said receivable programs or services a logical channel number (LCN), and in which is inserted in said second semi-multiplex (B) a third Network Information Table (NIT) type table, able to specify, for the radiotelevision programs or services of said second semi-multiplex (B), a target channel contained in said at least a portion of said frequency band and for each of said programs or services a logical channel number (LCN).

9. Method according to one or more of the claims 5 to 8, in which said multiplex is divided using a statistical satellite multiplex technique, in which the bit-rate of said first semi-multiplex (A) and of said second semi-multiplex (B) remain constant over time.

10. Multiplexer adapted to generate a satellite type multiplex designed for the transmission of radiotelevision signals of the terrestrial digital broadcasting type, comprising means for implementing the method according to one or more of the claims

11. Transmitter adapted to transmit satellite type signals comprising a multiplexer according to claim 10.

12. A method for receiving radiotelevision signals of the terrestrial digital broadcasting type, said radiotelevision signals being received via satellite and comprising a satellite type multiplex containing a plurality of programs or radiotelevision services, said method comprising the steps of:

a) receiving said satellite type radiotelevision signals containing said plurality of radiotelevision programs or services;

b) trans-modulating at least one of said satellite type radiotelevision signals through at least one trans-modulator (9, 9') that demodulates said satellite type radiotelevision signals and converts them into radiotelevision signals of the terrestrial digital broadcasting type and inserts the latter in a channel belonging to a portion of the band that has been discontinued for terrestrial digital broadcasting;

c) distributing said radiotelevision signals of the terrestrial digital broadcasting type via coaxial cable to an antenna distribution system.

13. Method according to claim 12, wherein it is provided to upload portions of software code in a memory of said at least one trans-modulator (9, 9') which allows for automatically assigning radiotelevision services or programs contained in said radiotelevision signals received via satellite to at least one channel of said portion of said frequency band.

14. Method according to claim 13, wherein said portions of software code are updatable by a broadcaster through a satellite signal.

15. Method according to claim 12, wherein said at least one trans-modulator (9, 9') reads a descriptor contained in a Program Specific Information type (PSI) table, or

Service Information (SI) type, of said multiplex able to specify, for each of said programs or radiotelevision services, a target channel and generates a radiotelevision signal of the digital terrestrial broadcasted type that is inserted into a channel between those indicated in said descriptor containing all the programs or services to be placed in said channel.

16. Method according to claim 15, wherein said receiver reads a second descriptor able to specify the logical channel number (LCN), associated to each of said programs or radiotelevision services.

17. Method according to claim 16, wherein said table is a Network Information Table (NIT) table, or Service Description Table (SDT), or a Program Association Table (PAT).

18. Method according to claim 12, wherein said satellite multiplex comprises a first semi-multiplex (A) and a second semi-multiplex (B), and wherein said at least one trans-modulator (9, 9') reads in a Network Information Table (NIT) the target channel of the programs or services of one of the two semi-multiplexes (A,B), generates a radiotelevision signal of the digital terrestrial broadcasted type containing a new multiplex with all services or programs of said one of semi-multiplexes (A,B), and inserts said new multiplex in the channel indicated by said Network Information Table (NIT) table.

19. Method according to claim 18, wherein said at least one trans-modulator (9, 9') inserts in said new multiplex the Network Information Table (NIT) table relating to the channel on which it emits the signal, while it deletes the Network Information Table (NIT) table relative to the channel in which is inserted the other of said two semi- multiplexes (A, B).

20. Installation for the reception of radiotelevision signals of the terrestrial digital broadcasted type, comprising means to implement the reception method according to one or more of the claims from 1 to 19.

21. Trans-modulator (9, 9') comprising:

- a tuner (20) able to tune into a satellite signal received in the band of the first intermediate frequency;

- a demodulator (21) able to demodulate the output signal from the tuner (20), extracting a multiplex of said satellite signal;

- extraction and rearrangement means (23) for extracting the components that make up said multiplex in order to identify every program or radiotelevision service through the information contained within said multiplex, such as information contained in the Program Specific Information (PSI) type tables, or Service Information (SI);

- modulation and frequency conversion means (24, 25) for generating radiotelevision signals of the terrestrial digital broadcasting type to be inserted only in channels belonging to a frequency band that has been discontinued for the airing of signals of the terrestrial digital broadcasted type and assigned to a different service, in particular to a mobile telephony service, such as the LTE type.

22. Trans-modulator (9, 9') comprising from among software code portions that can be uploaded to a memory of said trans-modulator (9, 9') which allow for automatically assigning radiotelevision programs or services contained in said multiplex to at least a channel belonging to a portion of said frequency band.

23. Trans-modulator (9, 9') according to claim 21, wherein said extraction and rearrangement means (23) use said components for generating a new multiplex comprising a number of programs or services less than said multiplex received and selected according to a priority criterion, for example only selecting radiotelevision programs or services of interest to the user, in particular the most important, at a national television broadcasting level.

24. Trans-modulator (9') according to claim 21, wherein said satellite multiplex comprises a first semi-multiplex (A) and a second semi-multiplex (B), each of which is associated with a respective Network Information Table (NIT) table with an indication of a respective target channel chosen among those belonging to a portion of bandwidth no longer in use for terrestrial digital broadcasting, wherein said radiotelevision signal of the digital terrestrial broadcasting type includes two channels of radiotelevision signals of the terrestrial digital broadcasting type, containing respectively all of the programs or services of one of said two semi-multiplexes (A,B), and inserted in the channels indicated by the respective Network Information Table (NIT) tables, and wherein said trans-modulator (9') inserts in each of said two radiotelevision signals of the terrestrial digital broadcasting type the relative NIT table, while it does not insert the Network Information Table (NIT) table relative to the other channel.

25. System for the transmission of radiotelevision signals of the terrestrial digital broadcasting type, said radiotelevision signals comprising a plurality of radiotelevision programs or services receivable by a receiver in a certain frequency band, wherein at least a portion of said frequency band has been discontinued for radiotelevision signals of the terrestrial digital broadcasting type and assigned to a different service, in particular to a mobile telephony service, for example of the LTE type, said system comprising:

- means for transmitting satellite type radiotelevision signals containing said receivable programs or television services;

- means for receiving said satellite type radiotelevision signals containing said plurality of receivable programs or television services;

- means for trans-modulating said satellite type radiotelevision signals by way of at least one trans-modulator (9,9') that demodulates said satellite type radiotelevision signals and converts them to radiotelevision signals of the terrestrial digital broadcasting type;

- means for distributing said radiotelevision signals containing said plurality of receivable television programs or services via coaxial cable in an antenna distribution installation, using only television channels of said at least a portion of said discontinued frequency band.

26. System for the transmission of radiotelevision signals of the terrestrial digital broadcasting type, said radiotelevision signals comprising a plurality of radiotelevision programs or services receivable by a receiver in a certain frequency band, wherein at least a portion of said frequency band has been discontinued for radiotelevision signals of the terrestrial digital broadcasting type and assigned to a different service, in particular to a mobile telephony service, for example of the LTE type, according to one or more of the method claims from 1 to 19.