WO2003084217A1 - Dvb-t to dvb-s converter - Google Patents

Dvb-t to dvb-s converter Download PDF

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Publication number
WO2003084217A1
WO2003084217A1 PCT/IB2003/001035 IB0301035W WO03084217A1 WO 2003084217 A1 WO2003084217 A1 WO 2003084217A1 IB 0301035 W IB0301035 W IB 0301035W WO 03084217 A1 WO03084217 A1 WO 03084217A1
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WO
WIPO (PCT)
Prior art keywords
dvb
signal
terrestrial
satellite
antenna
Prior art date
Application number
PCT/IB2003/001035
Other languages
French (fr)
Inventor
Hervé Benoit
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Priority to AU2003208551A priority Critical patent/AU2003208551A1/en
Publication of WO2003084217A1 publication Critical patent/WO2003084217A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H40/00—Arrangements specially adapted for receiving broadcast information
    • H04H40/18—Arrangements characterised by circuits or components specially adapted for receiving
    • H04H40/27—Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups H04H20/53 - H04H20/95
    • H04H40/90—Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups H04H20/53 - H04H20/95 specially adapted for satellite broadcast receiving
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
    • H04N21/438—Interfacing the downstream path of the transmission network originating from a server, e.g. retrieving encoded video stream packets from an IP network
    • H04N21/4382—Demodulation or channel decoding, e.g. QPSK demodulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/45—Management operations performed by the client for facilitating the reception of or the interaction with the content or administrating data related to the end-user or to the client device itself, e.g. learning user preferences for recommending movies, resolving scheduling conflicts
    • H04N21/462—Content or additional data management, e.g. creating a master electronic program guide from data received from the Internet and a Head-end, controlling the complexity of a video stream by scaling the resolution or bit-rate based on the client capabilities
    • H04N21/4622—Retrieving content or additional data from different sources, e.g. from a broadcast channel and the Internet
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/4446—IF amplifier circuits specially adapted for B&W TV
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/20—Adaptations for transmission via a GHz frequency band, e.g. via satellite
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/46—Receiver circuitry for the reception of television signals according to analogue transmission standards for receiving on more than one standard at will

Definitions

  • the invention relates to digital television. More particularly, it relates to a receiver and to a converter apparatus for enabling to receive, via a terrestrial antenna and via a DVB-S-like receiver suited for receiving a DVB-S video signal encoded in the Satellite Digital Video Broadcasting format (DVB-S), a DVB-T video signal encoded in the Terrestrial Digital Video Broadcasting format (DVB-T).
  • DVD-S Satellite Digital Video Broadcasting format
  • DVD-T Terrestrial Digital Video Broadcasting format
  • the international patent application published under number WO 99/37093 describes a system for the distribution in a collective environment of a plurality of television signals, transmitted with different standards.
  • one or more digital signals can be received by a single user of the system by means of a frequency conversion into a predetermined channel, which can be accessed by said user only.
  • the digital signal present in said channel always has the same modulation and can be selected by said user through control means, which send a control signal to selection means.
  • This avoids the user of a collective environment to have different types of modulators with respect to the different digital signals available to the collective environment.
  • the system applies to collective distribution of different digital television signals towards a plurality of receivers, for enabling the plurality of receivers to receive the programs, which reach the collective environment. It does not apply to individual reception, using a single receiver, of a digital television signal transmitted with a standard which is different from the standard compatible with the single receiver.
  • the invention takes the following aspects into consideration.
  • Digital terrestrial television has started in a few European countries (e.g. United Kingdom, Sweden, Spain, etc) and is now expanding to most European countries.
  • consumers are more or less reluctant to get the appropriate additional equipment (set-top box) needed to receive the new programs, which are transmitted in a specific digital format (DVB-T).
  • set-top box a specific digital format
  • the growth rate of subscriptions to the DVB-T television standard has been relatively low, partly due to the cost of the additional set-top box equipment.
  • there are already an important number of installed DVB-S set- top boxes the owners of which are not ready to pay for an extra, relatively costly and cumbersome, set-top box.
  • existing DVB-S service providers which want to launch a new DVB-T service, would have to invest a lot of money to acquire appropriate equipment.
  • the present invention provides DVB-T to DVB-S converting means for converting a DVB-T signal into a DVB-S signal to be processed by a DVB-S-like set-top box using a simple and inexpensive converter as an add-on to the existing DVB-S set-top box, possibly without any hardware adaptation on the box.
  • the DVB-S set-top box users would thus be able to re-use their existing box to receive new DVB-T programs by adding a low-cost converter, and DVB-S service providers would be able to re-use their already installed base of set-top boxes, thus limiting their investment.
  • a converter apparatus for delivering from a DVB-T signal including a set of multiplexed data such as TV and/or audio programs and/or other data encoded in the Terrestrial Digital Video Broadcasting format (DVB-T) and transmitted via a terrestrial antenna, a modulated signal to be applied to a satellite antenna input of a DVB-S receiver suited for receiving a DVB-S signal broadcast from a satellite and encoded in the Satellite Digital Video Broadcasting format (DVB-S).
  • the converter apparatus is to be connected to the terrestrial antenna and to the satellite antenna input. It comprises:
  • ⁇ tuning means for selecting via the terrestrial antenna a DVB-T signal to be received from a set of available DVB-T signals encoded in the Terrestrial Digital Video Broadcasting format (DVB-T), ⁇ a control device for controlling the tuning means in order to select the DVB-T signal from said set of DVB-T signals,
  • DVD-T Terrestrial Digital Video Broadcasting format
  • ⁇ a channel decoder for decoding said received DVB-T multiplexed video signal and for recovering a demodulated DVB-T transport stream, ⁇ a DVB-S modulator for re-modulating said recovered demodulated DVB-T signal into a modulated signal to be applied to said antenna input of the DVB-S receiver.
  • control device uses the DiSEqCTM signaling protocol for controlling the converter device.
  • the converter apparatus is supplied by the power supply of the Low Noise Block converter (LNB) of the DVB-S receiver.
  • LNB Low Noise Block converter
  • the converter apparatus is thus supplied by the LNB power supply and controlled by the DiSEqCTM signaling tone.
  • Fig. 1 is a conceptual diagram illustrating basic features of the invention as claimed in claim 1 ,
  • Figs. 2 to is a conceptual diagram illustrating additional features as claimed in dependent claims.
  • Fig. 1 illustrates an apparatus 10 in accordance with the invention for delivering, from a DVB-T signal selected from a set of available DVB-T signals transmitted via a terrestrial antenna 11 and encoded in the DVB-T format, a DVB-S modulated signal to be applied to a satellite antenna input, denoted LNBin, of a DVB-S receiver 12.
  • Each DVB-T signal comprises a set of data, such as TV and/or audio programs and/or other data.
  • the DVB-S receiver 12 is suited for receiving a DVB-S video signal broadcast from a satellite.
  • the apparatus 10 converts the DVB-T signal into a DVB-S signal. It is connected to the terrestrial antenna 11 and to the satellite antenna input LNBin. It comprises:
  • a tuner for receiving, via the terrestrial antenna 11 , a DVB-T signal, denoted Tin, selected from a set of available DVB-T signals which can be modulated, e.g. in accordance with the COFDM modulation (Coded Orthogonal Frequency
  • CTRL remote-controlled by the DVB-S receiver 12, for controlling the tuner TUN in order to select the DVB-T signal to be received from the set of available DVB-T signals
  • ⁇ a channel decoder, denoted DEC, for decoding the selected COFDM/DVB-T signal Tin and for recovering a demodulated and error corrected ("quasi error free") DVB-T signal or "transport stream", denoted TS, including said set of TV and/or audio programs and/or other data transmitted within the DVB-T signal, - a modulator, denoted MOD, for re-modulating said recovered demodulated DVB-T signal TS into a modulated signal, denoted Sout, in accordance with e.g. the QPSK (Quadrature Phase Shift Keying) modulation to be applied to said antenna input of the DVB-S receiver.
  • DEC demodulated and error corrected
  • TS transport stream
  • MOD for re-modulating said recovered demodulated DVB-T signal TS into a modulated signal, denoted Sout, in accordance with e.g. the QPSK (Quadrature Phase Shift Keying) modulation to be applied to
  • the tuner TUN receives a multiplexed COFDM terrestrial DVB-T TV signal Tin and delivers a multiplexed TV signal in an intermediate frequency (IF) to the channel decoder DEC.
  • IF intermediate frequency
  • the channel decoder DEC decodes the multiplexed signal and recovers the MPEG-2 "transport stream" signal TS corresponding to the transmitted multiplexed digital TV signal including a set of TV programs encoded in accordance with the MPEG-2 standard.
  • the modulator MOD builds up the QPSK modulated DVB-S signal Sout, suitable to be applied to the DVB-S receiver, since DVB-S receivers accept QPSK modulated input signals in the Satellite Intermediate Frequency band (950 to 2150 MHz).
  • the modulator MOD would normally comprise some error correction algorithms, known as FEC (Forward Error Correction) algorithms (using e.g. Viterbi and Reed Solomon algorithms) for correcting transmission errors which may have occurred during transmission of the DVB-T signal though the terrestrial channel, generally using Hertzian links.
  • FEC Forward Error Correction
  • Viterbi and Reed Solomon algorithms e.g. Viterbi and Reed Solomon algorithms
  • the demodulated DVB-T signal which is available before error correction, denoted TD, could be used "as if to drive the QPSK modulator MOD, after some usual processing such as, conversion from serial to I/Q format, which is the format suited for QPSK modulation, level adaptation and pulse shaping (i.e. Nyquist filtering).
  • This alternative, simpler way of signal processing enables avoiding the full DVB-S encoding stages. This is possible in principle due to the fact that satellite (DVB-S) and terrestrial (DVB-T) digital television standards use the same forward error correction mechanisms and parameters.
  • the QPSK signal Sout applied to the input LNBin of the DVB- S receiver will thus contain errors, which will normally be within the correction possibilities of the FEC stages of the DVB-S demodulator.
  • Fig. 2 illustrates additional features of an apparatus 20 in accordance with a preferred embodiment of the invention.
  • the apparatus 20 comprises, in addition to the entities illustrated in Fig. 1, switching means 21 for enabling to switch from the terrestrial antenna 11 to a satellite antenna 24 and vice versa, enabling to receive also DVB-S programs broadcast by satellite.
  • the control device CTRL is preferably a microcontroller, suitably programmed to control the tuner, via a specific bus e.g. an I C bus. It can also control initial parameters of devices, within the converter, which need to be initialized, such as e.g. the tuner, the channel decoder and the modulator.
  • the control means CTRL also comprise a DiSEqCTM standard compatible decoder for remote control of at least the tuner TUN and, if a satellite antenna 24 is to be used, the switch 21.
  • Most recent DVB-S receivers provide the DiSEqCTM signaling protocol, which is meant to transmit digital information for remote control of the satellite antenna by modulating the 22KHz tone used for band switching of the LNB.
  • the DiSEqCTM signaling protocol is used for controlling the tuner TUN, and possibly the switch.
  • the aim of the LNB of a satellite antenna is to convert the (high) frequency of the signal received from a satellite into a lower frequency suitable for cable transmission.
  • the signal received from the satellite is generally transmitted with 2 orthogonal polarizations and has to be split into 2 separate frequency bands by the LNB, each band containing a set of different radio frequency channels.
  • the DVB-S receiver has thus to select one out of 4 possibilities in order to receive a set of channels. Band selection is performed by control of the LNB of the antenna.
  • a DVB-T signal is selected using the tuner TUN, which tunes a physical channel.
  • the tuner is controlled with the control device CTRL using preferably the DiSEqCTM signaling protocol or another means of controlling the LNB, and/or possibly an Infra-Red (IR) signal, as described hereafter.
  • the DVB-S receiver supplies power to the LNB of the satellite dish (13-18V / 250 mA min). This voltage can take 2 values (13V or 18V) in order to select the polarization of the LNB.
  • the frequency band of the LNB can be selected by either superimposing or not a 22 KHz continuous signal on the supply voltage.
  • up to 4 physical channels can be selected by the DVB-T to DVB-S converter by using these 2 different supply voltage values with or without superimposition of a 22 KHz signal. To be able to select more than 4 channels, there are two options. The first one consists of using an extra Infra-Red (IR) signal for remote control of the radio channel selection.
  • IR Infra-Red
  • the second option consists of using the DiSEqCTM signaling tone to control the channel selection with the 22 KHz signal, which is modulated by a digital message sent from the DVB-S receiver.
  • a DiSEqCTM decoder is provided within the control device CTRL, enabling to receive and decode sophisticated digital messages for the channel selection control. Therefore, the converter apparatus in accordance with the preferred embodiment of the invention is supplied by the LNB power supply and controlled by the DiSEqCTM signaling tone, if this option is available in the DVB-S receiver. If not, the first option can be used (IR signal). Without any of these options, only 4 multiplexes can be received, using the basic couple of power supply (13/18 Volts) and the 22 KHz continuous signal.
  • a full control of the converter (antenna switch, DVB-T input frequency and other possible options) for a fully free selection of the DVB-T multiplex to be received requires a special option of the DiSEqCTM protocol, such as DiSEqCTM 1.1, initially intended for controlling a remote frequency converter in a satellite community antenna system. Since implementation of DiSEqCTM 1.1 version does not require additional hardware compared to a DiSEqCTM 1.0 version, which is available on most recent DVB-S receivers, these receivers could be upgraded to 1.1 by downloading the appropriate software allowing full control of the converter. Receivers only equipped with DiSEqCTM "ToneBurst" or 1.0 versions (e.g.
  • selection of one of 4 predefined physical channels, or multiplexes could then be done by using the 13 / 18 V and 0 / 22KHz switching signals (polarization and band control) and the programs of these multiplexes can be found and stored by the STB in the same way as satellite channels.
  • selection of the program by the user within a DVB-T multiplex as well as conditional access and other more sophisticated options, such as for example an Electronic Program Guide (EPG), are performed in the same way as for satellite channels, by means of the existing hardware, software and user interface of the DVB-S receiver.
  • EPG Electronic Program Guide
  • DVB-S Satellite Digital Video Broadcasting
  • DVB-T Terrestrial Digital Video Broadcasting
  • FEC Forward Error Correction
  • COFDM Coded Orthogonal Frequency Division Multiplexing
  • QPSK Quadrature Phase Shift Keying
  • MPEG-2 Motion Pictures Expert Group-2 DiSEqCTM:Digital Satellite Equipment Control
  • LNB Low Noise Block Converter I 2 C (or IIC): Inter-Integrated Circuit bus

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Astronomy & Astrophysics (AREA)
  • General Physics & Mathematics (AREA)
  • Databases & Information Systems (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)

Abstract

The invention relates to a trans-modulator for enabling to receive via a terrestrial antenna and via a DVB-S-like receiver suited for receiving a QPSK/DVB-S video signal encoded in the Satellite Digital Video Broadcasting format (DVB-S), a COFDM/DVB-T video signal encoded in the Terrestrial Digital Video Broadcasting format (DVB-T).

Description

DNB-T to DNB-S converter
FIELD OF THE INVENTION
The invention relates to digital television. More particularly, it relates to a receiver and to a converter apparatus for enabling to receive, via a terrestrial antenna and via a DVB-S-like receiver suited for receiving a DVB-S video signal encoded in the Satellite Digital Video Broadcasting format (DVB-S), a DVB-T video signal encoded in the Terrestrial Digital Video Broadcasting format (DVB-T).
BACKGROUND ART
The international patent application published under number WO 99/37093 describes a system for the distribution in a collective environment of a plurality of television signals, transmitted with different standards. In accordance with the system, one or more digital signals can be received by a single user of the system by means of a frequency conversion into a predetermined channel, which can be accessed by said user only. The digital signal present in said channel always has the same modulation and can be selected by said user through control means, which send a control signal to selection means. This avoids the user of a collective environment to have different types of modulators with respect to the different digital signals available to the collective environment. The system applies to collective distribution of different digital television signals towards a plurality of receivers, for enabling the plurality of receivers to receive the programs, which reach the collective environment. It does not apply to individual reception, using a single receiver, of a digital television signal transmitted with a standard which is different from the standard compatible with the single receiver.
SUMMARY OF THE INVENTION It is an object of the invention to enable individual reception of a digital signal coming from a terrestrial channel, using a satellite receiver for the reception of the terrestrial digital signal.
The invention takes the following aspects into consideration. Digital terrestrial television has started in a few European countries (e.g. United Kingdom, Sweden, Spain, etc) and is now expanding to most European countries. Depending on the added value of new programs offers, consumers are more or less reluctant to get the appropriate additional equipment (set-top box) needed to receive the new programs, which are transmitted in a specific digital format (DVB-T). Until now, the growth rate of subscriptions to the DVB-T television standard has been relatively low, partly due to the cost of the additional set-top box equipment. On the other hand, there are already an important number of installed DVB-S set- top boxes, the owners of which are not ready to pay for an extra, relatively costly and cumbersome, set-top box. Furthermore, existing DVB-S service providers, which want to launch a new DVB-T service, would have to invest a lot of money to acquire appropriate equipment.
Therefore, the present invention provides DVB-T to DVB-S converting means for converting a DVB-T signal into a DVB-S signal to be processed by a DVB-S-like set-top box using a simple and inexpensive converter as an add-on to the existing DVB-S set-top box, possibly without any hardware adaptation on the box. The DVB-S set-top box users would thus be able to re-use their existing box to receive new DVB-T programs by adding a low-cost converter, and DVB-S service providers would be able to re-use their already installed base of set-top boxes, thus limiting their investment.
This is actually possible, since the major difference between a DVB-S and a DVB-T box is the front-end, due to the different frequencies and modulation schemes used. But it is generally not possible to connect an additional front-end to an existing set-top box, because most of them do not provide an access to the "transport stream" input of the decoder, in accordance with the MPEG-2 (Moving Picture Expert Group-2) standard.
In accordance with the invention there is provided a converter apparatus for delivering from a DVB-T signal including a set of multiplexed data such as TV and/or audio programs and/or other data encoded in the Terrestrial Digital Video Broadcasting format (DVB-T) and transmitted via a terrestrial antenna, a modulated signal to be applied to a satellite antenna input of a DVB-S receiver suited for receiving a DVB-S signal broadcast from a satellite and encoded in the Satellite Digital Video Broadcasting format (DVB-S). The converter apparatus is to be connected to the terrestrial antenna and to the satellite antenna input. It comprises:
■ tuning means for selecting via the terrestrial antenna a DVB-T signal to be received from a set of available DVB-T signals encoded in the Terrestrial Digital Video Broadcasting format (DVB-T), ■ a control device for controlling the tuning means in order to select the DVB-T signal from said set of DVB-T signals,
■ a channel decoder for decoding said received DVB-T multiplexed video signal and for recovering a demodulated DVB-T transport stream, ■ a DVB-S modulator for re-modulating said recovered demodulated DVB-T signal into a modulated signal to be applied to said antenna input of the DVB-S receiver.
In accordance with another aspect of the invention, the control device uses the DiSEqC™ signaling protocol for controlling the converter device.
In accordance with a further aspect of the invention, the converter apparatus is supplied by the power supply of the Low Noise Block converter (LNB) of the DVB-S receiver.
In accordance with a preferred embodiment of the invention, the converter apparatus is thus supplied by the LNB power supply and controlled by the DiSEqC™ signaling tone.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described in the drawings hereinafter, wherein:
Fig. 1 is a conceptual diagram illustrating basic features of the invention as claimed in claim 1 ,
Figs. 2 to is a conceptual diagram illustrating additional features as claimed in dependent claims.
DETAILED DESCRIPTION OF THE DRAWINGS The drawings illustrate an example of a DVB-T to DVB-S converter using existing standards and systems. Therefore, COFDM (Coded Orthogonal Frequency Division Multiplexing) and QPSK (Quadrature Phase Shift Keying) modulations are mentioned. But the invention is not limited to these modulation techniques.
Fig. 1 illustrates an apparatus 10 in accordance with the invention for delivering, from a DVB-T signal selected from a set of available DVB-T signals transmitted via a terrestrial antenna 11 and encoded in the DVB-T format, a DVB-S modulated signal to be applied to a satellite antenna input, denoted LNBin, of a DVB-S receiver 12. Each DVB-T signal comprises a set of data, such as TV and/or audio programs and/or other data. The DVB-S receiver 12 is suited for receiving a DVB-S video signal broadcast from a satellite. The apparatus 10 converts the DVB-T signal into a DVB-S signal. It is connected to the terrestrial antenna 11 and to the satellite antenna input LNBin. It comprises:
■ a tuner, denoted TUN, for receiving, via the terrestrial antenna 11 , a DVB-T signal, denoted Tin, selected from a set of available DVB-T signals which can be modulated, e.g. in accordance with the COFDM modulation (Coded Orthogonal Frequency
Division Multiplexing), and for delivering an COFDM modulated DVB-T signal to a channel decoder in an intermediate frequency suitable for cable transmissions,
■ a control device, denoted CTRL, remote-controlled by the DVB-S receiver 12, for controlling the tuner TUN in order to select the DVB-T signal to be received from the set of available DVB-T signals,
■ a channel decoder, denoted DEC, for decoding the selected COFDM/DVB-T signal Tin and for recovering a demodulated and error corrected ("quasi error free") DVB-T signal or "transport stream", denoted TS, including said set of TV and/or audio programs and/or other data transmitted within the DVB-T signal, - a modulator, denoted MOD, for re-modulating said recovered demodulated DVB-T signal TS into a modulated signal, denoted Sout, in accordance with e.g. the QPSK (Quadrature Phase Shift Keying) modulation to be applied to said antenna input of the DVB-S receiver.
The features of the apparatus 10 illustrated in Fig. 1 provide the following effects. In the case of television (TV) transmission, for example, the same applying to any other type of data transmission, the tuner TUN receives a multiplexed COFDM terrestrial DVB-T TV signal Tin and delivers a multiplexed TV signal in an intermediate frequency (IF) to the channel decoder DEC. The channel decoder DEC decodes the multiplexed signal and recovers the MPEG-2 "transport stream" signal TS corresponding to the transmitted multiplexed digital TV signal including a set of TV programs encoded in accordance with the MPEG-2 standard. From this "transport stream", the modulator MOD builds up the QPSK modulated DVB-S signal Sout, suitable to be applied to the DVB-S receiver, since DVB-S receivers accept QPSK modulated input signals in the Satellite Intermediate Frequency band (950 to 2150 MHz). The modulator MOD would normally comprise some error correction algorithms, known as FEC (Forward Error Correction) algorithms (using e.g. Viterbi and Reed Solomon algorithms) for correcting transmission errors which may have occurred during transmission of the DVB-T signal though the terrestrial channel, generally using Hertzian links. In accordance with a simplified embodiment of the invention, it is expected that the direct and short cable connection between the converter and the satellite antenna input do not introduce additional transmission errors. The demodulated DVB-T signal, which is available before error correction, denoted TD, could be used "as if to drive the QPSK modulator MOD, after some usual processing such as, conversion from serial to I/Q format, which is the format suited for QPSK modulation, level adaptation and pulse shaping (i.e. Nyquist filtering). This alternative, simpler way of signal processing enables avoiding the full DVB-S encoding stages. This is possible in principle due to the fact that satellite (DVB-S) and terrestrial (DVB-T) digital television standards use the same forward error correction mechanisms and parameters. The QPSK signal Sout applied to the input LNBin of the DVB- S receiver will thus contain errors, which will normally be within the correction possibilities of the FEC stages of the DVB-S demodulator.
Fig. 2 illustrates additional features of an apparatus 20 in accordance with a preferred embodiment of the invention. Like entities as the ones illustrated in Fig. 1 are indicated by like letter references in Fig.2. The apparatus 20 comprises, in addition to the entities illustrated in Fig. 1, switching means 21 for enabling to switch from the terrestrial antenna 11 to a satellite antenna 24 and vice versa, enabling to receive also DVB-S programs broadcast by satellite. The control device CTRL is preferably a microcontroller, suitably programmed to control the tuner, via a specific bus e.g. an I C bus. It can also control initial parameters of devices, within the converter, which need to be initialized, such as e.g. the tuner, the channel decoder and the modulator.
In accordance with a preferred embodiment of the invention illustrated in Fig.2, the control means CTRL also comprise a DiSEqC™ standard compatible decoder for remote control of at least the tuner TUN and, if a satellite antenna 24 is to be used, the switch 21. Most recent DVB-S receivers provide the DiSEqC™ signaling protocol, which is meant to transmit digital information for remote control of the satellite antenna by modulating the 22KHz tone used for band switching of the LNB. In accordance with the preferred embodiment, the DiSEqC™ signaling protocol is used for controlling the tuner TUN, and possibly the switch. The aim of the LNB of a satellite antenna is to convert the (high) frequency of the signal received from a satellite into a lower frequency suitable for cable transmission. The signal received from the satellite is generally transmitted with 2 orthogonal polarizations and has to be split into 2 separate frequency bands by the LNB, each band containing a set of different radio frequency channels. The DVB-S receiver has thus to select one out of 4 possibilities in order to receive a set of channels. Band selection is performed by control of the LNB of the antenna.
In terrestrial digital television, a DVB-T signal is selected using the tuner TUN, which tunes a physical channel. In accordance with the preferred embodiment of Fig. 2, the tuner is controlled with the control device CTRL using preferably the DiSEqC™ signaling protocol or another means of controlling the LNB, and/or possibly an Infra-Red (IR) signal, as described hereafter.
The DVB-S receiver supplies power to the LNB of the satellite dish (13-18V / 250 mA min). This voltage can take 2 values (13V or 18V) in order to select the polarization of the LNB. In addition, the frequency band of the LNB can be selected by either superimposing or not a 22 KHz continuous signal on the supply voltage. Using the same principle, up to 4 physical channels can be selected by the DVB-T to DVB-S converter by using these 2 different supply voltage values with or without superimposition of a 22 KHz signal. To be able to select more than 4 channels, there are two options. The first one consists of using an extra Infra-Red (IR) signal for remote control of the radio channel selection. The second option consists of using the DiSEqC™ signaling tone to control the channel selection with the 22 KHz signal, which is modulated by a digital message sent from the DVB-S receiver. In accordance with this option, a DiSEqC™ decoder is provided within the control device CTRL, enabling to receive and decode sophisticated digital messages for the channel selection control. Therefore, the converter apparatus in accordance with the preferred embodiment of the invention is supplied by the LNB power supply and controlled by the DiSEqC™ signaling tone, if this option is available in the DVB-S receiver. If not, the first option can be used (IR signal). Without any of these options, only 4 multiplexes can be received, using the basic couple of power supply (13/18 Volts) and the 22 KHz continuous signal.
A full control of the converter (antenna switch, DVB-T input frequency and other possible options) for a fully free selection of the DVB-T multiplex to be received requires a special option of the DiSEqC™ protocol, such as DiSEqC™ 1.1, initially intended for controlling a remote frequency converter in a satellite community antenna system. Since implementation of DiSEqC™ 1.1 version does not require additional hardware compared to a DiSEqC™ 1.0 version, which is available on most recent DVB-S receivers, these receivers could be upgraded to 1.1 by downloading the appropriate software allowing full control of the converter. Receivers only equipped with DiSEqC™ "ToneBurst" or 1.0 versions (e.g. not upgraded or not upgradeable to 1.1) can only control the antenna switch of the converter to select DVB-T signals as if they were coming from a second satellite antenna. Receivers not equipped with any form of DiSEqC™ control could still use the converter by activating the switch between satellite and terrestrial reception either manually or by interpretation of a command of the remote control of the set-top box, which is not active during normal viewing of DVB-S programs.
In both cases, selection of one of 4 predefined physical channels, or multiplexes, could then be done by using the 13 / 18 V and 0 / 22KHz switching signals (polarization and band control) and the programs of these multiplexes can be found and stored by the STB in the same way as satellite channels. In all cases, selection of the program by the user within a DVB-T multiplex as well as conditional access and other more sophisticated options, such as for example an Electronic Program Guide (EPG), are performed in the same way as for satellite channels, by means of the existing hardware, software and user interface of the DVB-S receiver. The above drawings and their description illustrate rather than limit the invention. It will be evident that there are numerous alternatives, which fall within the scope of the appended claims. In this respect, the following final remarks are made.
There are numerous ways of implementing functions by means of items of hardware or software, or both. In this respect, the drawings are very diagrammatic, each representing only one possible embodiment of the invention. Thus, although a drawing shows different functions as different blocks, this by no means excludes that a single item of hardware or software carries out several functions, nor does it exclude that a function is carried out by an assembly of items of hardware or software, or both.
Any reference sign in a claim should not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Use of the article "a" or "an" preceding an element or step does not exclude the presence of a plurality of such elements or steps.
Definition of abbreviations: DVB-S: Satellite Digital Video Broadcasting DVB-T: Terrestrial Digital Video Broadcasting FEC: Forward Error Correction
COFDM: Coded Orthogonal Frequency Division Multiplexing QPSK: Quadrature Phase Shift Keying MPEG-2: Motion Pictures Expert Group-2 DiSEqC™:Digital Satellite Equipment Control LNB: Low Noise Block Converter I2C (or IIC): Inter-Integrated Circuit bus

Claims

CLAIMS:
1. A converter apparatus for delivering, from a DVB-T multiplexed video signal including a set of video programs encoded in the Terrestrial Digital Video Broadcasting format (DVB-T) and transmitted via a terrestrial antenna, a modulated signal to be applied to a satellite antenna input of a DVB-S receiver suited for receiving a DVB-S video signal broadcast from a satellite and encoded in the Satellite Digital Video Broadcasting format (DVB-S), said apparatus comprising connections to be connected to at least said terrestrial antenna and to said satellite antenna input, the apparatus comprising:
■ tuning means for selecting via the terrestrial antenna a DVB-T multiplexed video signal to be received from a set of available multiplexed video signals encoded in the Terrestrial Digital Video Broadcasting format (DVB-T), each multiplexed signal corresponding to a video program,
■ a control device for controlling the tuning means in order to select the DVB-T multiplexed video signal from said set of DVB-T multiplexed video signals,
■ a channel decoder for decoding said received DVB-T multiplexed video signal and for recovering a demodulated DVB-T video stream including a set of video programs,
■ a modulator for re-modulating said recovered demodulated DVB-T signal into a modulated signal to be applied to said antenna input of the receiver.
2. An apparatus as claimed in claim 1, wherein the control device comprises a decoder enabling to decode the DiSEqC™ signaling protocol used for remotely controlling the tuning means.
3. An apparatus as claimed in claim 1, wherein the DVB-T multiplexed video signal is transmitted through a terrestrial channel and wherein the converter device comprises an error correction device (FEC) for correcting transmission errors introduced during transmission of the DVB-T signal through the terrestrial channel.
4. Apparatus as claimed in claim 1 , the DVB-S receiver comprising a Low Noise
Band (LNB) power supply for supplying power to a satellite antenna, wherein the apparatus is supplied by said LNB power supply.
5. Apparatus as claimed in claim 1, the DVB-S receiver comprising a satellite antenna connected to said satellite antenna input, wherein the apparatus comprises switching means for enabling to switch from the terrestrial antenna to the satellite antenna and vice versa.
PCT/IB2003/001035 2002-03-29 2003-03-19 Dvb-t to dvb-s converter WO2003084217A1 (en)

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EP1791352A1 (en) * 2005-11-24 2007-05-30 Angel Iglesias S.A. DVB-S-to-DVB-T transmodulator
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NL1027547C2 (en) * 2004-11-19 2006-05-22 Tratec Telecom B V Communication system.
EP1659793A1 (en) * 2004-11-19 2006-05-24 Tratec Telecom B.V. Communication system
US8509716B2 (en) 2005-09-19 2013-08-13 Thomson Licensing Adaptive impedance for LNB power supply output in dependence on communication mode/protocol
EP1791352A1 (en) * 2005-11-24 2007-05-30 Angel Iglesias S.A. DVB-S-to-DVB-T transmodulator
DE102010036466A1 (en) * 2010-07-16 2012-01-19 Kurt Wolf Gmbh & Co. Kg Broadcast signal receiving and distributing device, e.g. for converting analogue satellite TV signals, has frequency converter that shifts satellite or terrestrial input signal into frequency range of digital signals for output to receiver

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