WO2005006753A1 - Transcoder for a cable network head - Google Patents

Transcoder for a cable network head Download PDF

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Publication number
WO2005006753A1
WO2005006753A1 PCT/EP2004/006272 EP2004006272W WO2005006753A1 WO 2005006753 A1 WO2005006753 A1 WO 2005006753A1 EP 2004006272 W EP2004006272 W EP 2004006272W WO 2005006753 A1 WO2005006753 A1 WO 2005006753A1
Authority
WO
WIPO (PCT)
Prior art keywords
control unit
cable network
transcoder
network head
transcoders
Prior art date
Application number
PCT/EP2004/006272
Other languages
French (fr)
Inventor
Christophe Vidon
Marc Louchkoff
Original Assignee
Thomson Licensing
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 Thomson Licensing filed Critical Thomson Licensing
Publication of WO2005006753A1 publication Critical patent/WO2005006753A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/10—Adaptations for transmission by electrical cable
    • H04N7/106—Adaptations for transmission by electrical cable for domestic distribution

Definitions

  • the invention relates to cable network heads for receiving and distributing digital services.
  • These cable network heads are now widely deployed in towns, districts, buildings and even in dwellings for picking up the multitude of digital services transmitted by satellites.
  • a cable network head comprises several types of antennas (parabolic, RF) by virtue of which it receives and centralizes the satellite signals. These signals are processed in transcoders and then distributed to the customers (television sets generally) connected to the cable network.
  • the function of each transcoder is to convert the digital signal picked up by the antennas on a reception channel into a baseband standardized audio and/or video signal according to one of standards PAL, SECAM, NTSC, etc.
  • a cable network head During utilization, a cable network head requires daily management and monitoring. This monitoring and management is generally carried out remotely by an operator from a terminal connected to the transcoders so as to allow an adjustment or a change of the reception channels onto which the transcoders are locked.
  • transcoders have been apparatus of the relatively sophisticated and hence expensive professional type, and on the other hand, the management terminal has been linked by wire links to the transcoders.
  • the aim of the invention is to afford a simpler solution for the design and management of a cable network head.
  • a subject of the invention is a transcoder for cable network head for receiving and distributing digital services, characterized in that it comprises a tuner and a modulator that are controlled by a control unit designed to be hooked up to a communication line of the carrier current power line type.
  • a transcoder according to the invention can exhibit the following features:
  • a photocoupler is provided between the control unit and the communication line;
  • control unit is designed to operate with a communication protocol of the master/slave type
  • control unit communicates over the communication line by utilizing a technique of spread spectrum data transmission with pseudo-random coding, in particular a dual-phase code L.
  • the invention extends to a cable network head comprising a set of transcoders (which are preferably mass-market digital decoders) linked to a master control unit by a communication line of the carrier current power line type, with the possibility of integrating the master control unit into one of the transcoders.
  • a transcoder according to the invention and of a cable network head according to the invention is described hereinbelow and illustrated in the single figure.
  • a head of a cable network for receiving and distributing digital services which comprises downstream of one or more antennas 1 for receiving digital signals, a bank of transcoders 2A, 2B, 2C, 2D linked in parallel by a coaxial downlink of 950 to 2150 MHz to a set of splitters 3A, 3B, 3C distributing the digital services to cable customers indicated by the reference 4.
  • a network head comprises a large number of transcoders, given the extended spectrum of digital services currently transmitted by satellites.
  • each transcoder 2A-2D Represented in each transcoder 2A-2D are a tuner 6 and a modulator 7 with adjustable frequency which are controlled by a control unit 5 intended to be hooked up to a communication line of the carrier current power line type L.
  • each transcoder is preferably an STB "set top box” or mass-market digital decoder in which the tuner 6 forms part of the "front end” and the modulator 7 forms part of the "back end” of the STB.
  • the tuner 6 as defined in the present patent application comprises a tuning facility and a demodulator, by way of example, such a circuit as under the reference DSF892X produced and marketed by the company THOMSON.
  • the modulator 7 corresponds, for example to the circuit produced and marketed by the company THOMSON under the reference MDU6060.
  • the local control unit 5 in a transcoder serves among other things for adjusting the frequency of the tuner 6 and of the modulator 7 and for the recovery of operating information.
  • the local control units 5 in the transcoders 2A-2D are configured to utilize a communication protocol of the master/slave type with a distant master control unit PLC which constitutes the monitoring and management terminal for the utilization of the cable network head.
  • the master/slave protocol is for example of the type implemented in respect of an I2C bus. This type of protocol is simple to implement, operates with a small bandwidth and makes it possible to circumvent the problems of network message collision. With time-division multiplexing in the duplex transmission of network messages, it is therefore easily possible to recover, in the master control unit PLC, information produced by the local slave control units 5 and conversely to send, to the local slave control units 5, information or commands from the master control unit PLC.
  • the local control unit 5 will advantageously be built into the data processor already present in such decoders. It will suffice to provide an additional input/output interface on the processor, advantageously a galvanically isolated interface such as a photocoupler.
  • the master control unit PLC is represented outside the cable network head, it is of course possible to make provision for it to be integrated into one of the transcoders 2A-2D.
  • the network messages flowing over the carrier current line L have a length of around four bytes in which is coded in particular the logical address of the control unit for which the network message is bound.
  • it is possible to make provision for a redundancy for example by repeating the same message several times, in the transmission of network messages so as to improve the efficiency and robustness of the communication.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)

Abstract

A transcoder (2A-2D) for a cable network head for receiving and distributing digital services comprises a tuner (6) and a modulator (7) that are controlled by a control unit (5) designed to be hooked up to a communication line of the carrier current power line type. This design affords a simplification in the construction of a cable network head.

Description

TRANSCODER FOR A CABLE NETWORK HEAD
The invention relates to cable network heads for receiving and distributing digital services. These cable network heads are now widely deployed in towns, districts, buildings and even in dwellings for picking up the multitude of digital services transmitted by satellites. Generally, a cable network head comprises several types of antennas (parabolic, RF) by virtue of which it receives and centralizes the satellite signals. These signals are processed in transcoders and then distributed to the customers (television sets generally) connected to the cable network. The function of each transcoder is to convert the digital signal picked up by the antennas on a reception channel into a baseband standardized audio and/or video signal according to one of standards PAL, SECAM, NTSC, etc.
During utilization, a cable network head requires daily management and monitoring. This monitoring and management is generally carried out remotely by an operator from a terminal connected to the transcoders so as to allow an adjustment or a change of the reception channels onto which the transcoders are locked. Up to now, on the one hand, transcoders have been apparatus of the relatively sophisticated and hence expensive professional type, and on the other hand, the management terminal has been linked by wire links to the transcoders.
In the case of a network head of reduced size, for example in a hotel or a very large house, the professional solutions are overdimensioned and expensive.
The aim of the invention is to afford a simpler solution for the design and management of a cable network head.
Accordingly, a subject of the invention is a transcoder for cable network head for receiving and distributing digital services, characterized in that it comprises a tuner and a modulator that are controlled by a control unit designed to be hooked up to a communication line of the carrier current power line type.
The idea underlying the invention may be applied to cable network heads of very different sizes but the invention applies more particularly to a cable network head of the SMATV ("Satellite Master Antenna Television") type in which each transcoder is a mass-market digital decoder. A transcoder according to the invention can exhibit the following features:
- a photocoupler is provided between the control unit and the communication line;
- the control unit is designed to operate with a communication protocol of the master/slave type;
- the control unit communicates over the communication line by utilizing a technique of spread spectrum data transmission with pseudo-random coding, in particular a dual-phase code L.
The invention extends to a cable network head comprising a set of transcoders (which are preferably mass-market digital decoders) linked to a master control unit by a communication line of the carrier current power line type, with the possibility of integrating the master control unit into one of the transcoders. An example of a transcoder according to the invention and of a cable network head according to the invention is described hereinbelow and illustrated in the single figure.
Represented very diagrammatically in the figure is a head of a cable network for receiving and distributing digital services which comprises downstream of one or more antennas 1 for receiving digital signals, a bank of transcoders 2A, 2B, 2C, 2D linked in parallel by a coaxial downlink of 950 to 2150 MHz to a set of splitters 3A, 3B, 3C distributing the digital services to cable customers indicated by the reference 4. It is obvious that a network head comprises a large number of transcoders, given the extended spectrum of digital services currently transmitted by satellites. Represented in each transcoder 2A-2D are a tuner 6 and a modulator 7 with adjustable frequency which are controlled by a control unit 5 intended to be hooked up to a communication line of the carrier current power line type L. According to the invention, each transcoder is preferably an STB "set top box" or mass-market digital decoder in which the tuner 6 forms part of the "front end" and the modulator 7 forms part of the "back end" of the STB. The tuner 6 as defined in the present patent application comprises a tuning facility and a demodulator, by way of example, such a circuit as under the reference DSF892X produced and marketed by the company THOMSON. The modulator 7 corresponds, for example to the circuit produced and marketed by the company THOMSON under the reference MDU6060. The local control unit 5 in a transcoder serves among other things for adjusting the frequency of the tuner 6 and of the modulator 7 and for the recovery of operating information.
The local control units 5 in the transcoders 2A-2D are configured to utilize a communication protocol of the master/slave type with a distant master control unit PLC which constitutes the monitoring and management terminal for the utilization of the cable network head. The master/slave protocol is for example of the type implemented in respect of an I2C bus. This type of protocol is simple to implement, operates with a small bandwidth and makes it possible to circumvent the problems of network message collision. With time-division multiplexing in the duplex transmission of network messages, it is therefore easily possible to recover, in the master control unit PLC, information produced by the local slave control units 5 and conversely to send, to the local slave control units 5, information or commands from the master control unit PLC.
It is known that carrier current lines exhibit strong electromagnetic disturbances. This is why, for the transmission of network messages between the control units 5 and the control unit PLC, provision is advantageously made to use a spread spectrum technique with a pseudo- random coding of the data, for example a dual-phase code L such as defined by the IEEE802.3 standard.
If mass-market digital decoders are used as transcoders for a cable network head, the local control unit 5 will advantageously be built into the data processor already present in such decoders. It will suffice to provide an additional input/output interface on the processor, advantageously a galvanically isolated interface such as a photocoupler. Although in the figure the master control unit PLC is represented outside the cable network head, it is of course possible to make provision for it to be integrated into one of the transcoders 2A-2D. The network messages flowing over the carrier current line L have a length of around four bytes in which is coded in particular the logical address of the control unit for which the network message is bound. In the communication protocol, it is possible to make provision for a redundancy, for example by repeating the same message several times, in the transmission of network messages so as to improve the efficiency and robustness of the communication.

Claims

1. A transcoder for cable network head for receiving and distributing digital services, characterized in that it comprises a tuner (6) and a modulator (7) that are controlled by a control unit (5) designed to be hooked up to a communication line of the carrier current power line type.
2. The transcoder as claimed in claim 1 , in which a photocoupler is provided between the control unit (5) and the communication line.
3. The transcoder as claimed in one of claims 1 to 2, in which the control unit (5) is designed to operate with a communication protocol of the master/slave type.
4. The transcoder as claimed in one of claims 1 to 3, in which the control unit (5) communicates over the communication line by utilizing a technique of spread spectrum data transmission with pseudo-random coding.
5. A cable network head comprising a set of transcoders (2A-2D) as claimed in one of claims 1 to 4 linked to a master control unit (PLC) by a communication line of the carrier current power line type.
6. The cable network head as claimed in claim 5, in which the master control unit (PLC) is integrated into one of the transcoders.
7. The cable network head as claimed in claim 5 or 6, in which the transcoders (5) are digital decoders.
PCT/EP2004/006272 2003-07-01 2004-06-04 Transcoder for a cable network head WO2005006753A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0307931A FR2857189A1 (en) 2003-07-01 2003-07-01 TRANSCODER FOR CABLE NETWORK HEAD
FR0307931 2003-07-01

Publications (1)

Publication Number Publication Date
WO2005006753A1 true WO2005006753A1 (en) 2005-01-20

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2004/006272 WO2005006753A1 (en) 2003-07-01 2004-06-04 Transcoder for a cable network head

Country Status (2)

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FR (1) FR2857189A1 (en)
WO (1) WO2005006753A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1713271A1 (en) * 2005-04-15 2006-10-18 Syen S.r.l. Digital to analog television signal converter

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6216250B1 (en) * 1997-01-27 2001-04-10 Hughes Electronics Corporation Error encoding method and apparatus for satellite and cable signals

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6216250B1 (en) * 1997-01-27 2001-04-10 Hughes Electronics Corporation Error encoding method and apparatus for satellite and cable signals

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
ROSTAMI M ET AL: "Multi-decoder digital television platform", PROCEEDINGS OF THE 28TH EUROMICRO CONFERENCE, 4 September 2002 (2002-09-04), pages 170 - 175, XP010612143 *
WAY W I ET AL: "A new method of distributing analog CATV and POTS on fiber to the home", IEEE GLOBAL TELECOMMUN CONF AND EXHIB COMMUN FOR THE INF AGE, 28 November 1988 (1988-11-28), NEW YORK, NY, USA, pages 1601 - 1606, XP010071836 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1713271A1 (en) * 2005-04-15 2006-10-18 Syen S.r.l. Digital to analog television signal converter

Also Published As

Publication number Publication date
FR2857189A1 (en) 2005-01-07

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