GB2232561A - Television transmission via a satellite transponder - Google Patents

Television transmission via a satellite transponder Download PDF

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Publication number
GB2232561A
GB2232561A GB8913391A GB8913391A GB2232561A GB 2232561 A GB2232561 A GB 2232561A GB 8913391 A GB8913391 A GB 8913391A GB 8913391 A GB8913391 A GB 8913391A GB 2232561 A GB2232561 A GB 2232561A
Authority
GB
United Kingdom
Prior art keywords
transponder
satellite
sound
transmitted
component
Prior art date
Legal status (The legal status 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 status listed.)
Granted
Application number
GB8913391A
Other versions
GB2232561B (en
GB8913391D0 (en
Inventor
Paul Matthews
David Gregory
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems PLC
Original Assignee
British Aerospace PLC
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 British Aerospace PLC filed Critical British Aerospace PLC
Priority to GB8913391A priority Critical patent/GB2232561B/en
Publication of GB8913391D0 publication Critical patent/GB8913391D0/en
Publication of GB2232561A publication Critical patent/GB2232561A/en
Application granted granted Critical
Publication of GB2232561B publication Critical patent/GB2232561B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/18523—Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/04—Systems for the transmission of one television signal, i.e. both picture and sound, by a single carrier
    • H04N7/045—Systems for the transmission of one television signal, i.e. both picture and sound, by a single carrier the carrier being frequency modulated
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/08—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division
    • 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
    • H04N11/00—Colour television systems
    • H04N11/06—Transmission systems characterised by the manner in which the individual colour picture signal components are combined
    • H04N11/08—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using sequential signals only

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Astronomy & Astrophysics (AREA)
  • General Physics & Mathematics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Television Systems (AREA)

Abstract

Television signals are transmitted to a satellite transponder, by transmitting a video component 6, 7 of a MAC television signal from a first uplink earthstation in the satellite's coverage area to the transponder, and by transmitting a sound and/or data component 8 of the MAC television signal from a second separate uplink earthstation in the satellite's coverage area to the transponder. Both components 6, 7 and 8 are transmitted using time division multiplex in a manner such that each component 6, 7 and 8 individually saturates the transponder for the period of time it is applied to the transponder. <IMAGE>

Description

TELEVISION TRANSMISSION VIA A SATELLITE TRANSPONDER This invention relates to television transmission via a satellite transponder and concerns, particularly but not exclusively, a method of transmitting television signals to a satellite transponder.
To obtain maximum performance from a satellite transponder only one radio frequency "carrier" signal is applied to it at a sufficient amplitude to drive the transponder into the highly efficient, non-linear, saturated mode of the travelling wave tube amplifier (TWTA). This is the normal way of working for television transmissions when one signal is applied to each transponder on a satellite.
A complete television signal normally requires pictures and sound and, for new systems, data transmissions. Various systems have been proposed for transmitting these component parts on a single carrier wave including the use of video "subcarriers", BBC's "Sound-in-Sync" system and varieties of the "Multiple Analogue Component" (MAC) system developed by the Independent Broadcasting Authority in the United Kingdom.
If the component parts of a television signal are transmitted as separate entities each on their own carrier wave then the satellite transponder must be "backed-off" by reducing the signal levels applied to it to operate in the linear mode. Such working, termed frequency division multiplex, is not very efficient and leads to less intense transmissions from the satellite in turn necessitating the use of larger receiving earthstations.
For particular reasons connected with customers' requirements, the picture signal is sometimes generated at one location in the satellite's uplink coverage area and the sound and data signals at other places. It would then be more economic and operationally convenient to be able to transmit the component parts of the signal direct to the satellite through separate uplink stations located where the signals are generated rather than to use terrestrial telecommunications lines to bring all the components to one place for uplinking.
Up to now, the only way this has been possible is by the use of the satellite transponder in the linear mode using frequency division multiplex, by transmitting the separate components through one transponder on separate carrier waves.
The result of this is that the transponder is working less efficiently and the receiving stations are not only larger but also have separately to intercept the component parts and assemble the complete television service.
There is thus a need for an improved method of transmitting television signals to a satellite transponder which avoids the foregoing problems and which avoids the necessity for video and sound/ data components of a television transmission signal to be formatted at a common location as is required for current MAC systems.
According to one aspect of the present invention there is provided a method of transmitting television signals to a satellite transponder in which a video component of a MAC television signal is transmitted from a first, uplink earthstation in the satellite's coverage area to the transponder, and a sound andlor data component of the MAC television signal is transmitted from a second separate uplink earthstation in the satellite's coverage area to the transponder, with both said components being transmitted using time division multiplex in a manner such that each said component individually saturates the transponder for the period of time it is applied to the transponder.
Advantageously the video component includes chrominance and luminance information.
Preferably both sound and data components are formatted at the second uplink earthstation.
For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which Figure 1 is a diagrammatic, schematic graphical view of a conventional terrestrial television transmission system (PAL) in which luminance, chrominance and sound components are transmitted as individual signals, Figure 2 is a diagrammatic view of a conventional MAC format television transmission signal, Figure 3 is a diagrammatic view of a video component of a transmission method according to the present invention, and Figure 4 is a diagrammatic view of a sound and! our -data component of a transmission method according to the present invention.
As shown in Figure 1 of the accompanying drawings a conventional terrestrial television transmission system (PAL) has a video component made up of luminance 1 and chrominance 2 parts and a sound and/or data part which are all transmitted as individual signals.
Although this method can be used for satellite operation, the presence of multiple carriers at the satellite input does mean that the satellite transponder must work in a less efficient "backed-off" mode. To overcome this problem, a series of transmission standards known as MAC (Multiplexed Analogue Component) were developed by the Independent Broadcasting Authority. Several MAC formats have been devised but the basic concept of each format is the same. A single carrier is employed to transmit the sound and data 3 chrominance 4 and luminance 5 components as shown in Figure 2. The chrominance and luminance components 4,5 are compressed and transmitted together with a sound and/or data component 3 on a single line.
Transmissions of this nature are of better quality than conventional PAL formats and make more efficient use of the satellite.
For many applications, the sound and data components of the transmission originate from geographically separate locations.
It is necessary with the MAC systems currently available to convey the sound, data and video information to a single common location for formatting and transmission. For most practical purposes this necessitates the provision of sound, data or vision circuits by others, involving considerable additional expense and introducing potential delays.
The transmission method of the invention overcomes these constraints and allows transmission of the sound and data components whilst still enjoying the full benefits of MAC operation.
In the method of the invention for transmitting television signals to a satellite transponder, a video component as shown in Figure 3 of a MAC television signal is transmitted from a first, uplink earthstation in the satellite's coverage area to the transponder, and a sound and/or data component 8, as shown in Figure 4, of the MAC television signal is transmitted from a second separate uplink earthstation in the satellite's coverage area to the transponder. Both components are transmitted using time division multiplex in a manner such that each said component individually saturates the transponder for the period of time it is applied to the transponder.
The video component includes chrominance 6 and luminance 7 information.
The sound and data components 8 are formatted conventionally and transmitted without the video components.
The timing of the sound/data 8 and video 6,7 transmissions is very carefully controlled and the overall transmission is constantly monitored. At the reception site, the transmission will appear as a single MAC format signal and may be processed as normal by conventional equipment.

Claims (4)

1. A method of transmitting television signals to a satellite transponder, in which a video component of a MAC television signal is transmitted from a first uplink earthstation in the satellite's coverage area to the transponder, and a sound andlor data component of the MAC television signal is transmitted from a second separate uplink earthstation in the satellite's coverage area to the transponder, with both said components being transmitted using time division multiplex in a manner such that each said component individually saturates the transponder for the period of time it is applied to the transponder.
2. A method according to Claim 1, in which the video component includes chrominance and luminance information.
3. A method according to Claim 1 or Claim 2, in which both sound and data components are formatted at the second uplink earthstation.
4. A method of transmitting television signals to a satellite transponder, substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.
GB8913391A 1989-06-10 1989-06-10 Television transmission via a satellite transponder Expired - Fee Related GB2232561B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8913391A GB2232561B (en) 1989-06-10 1989-06-10 Television transmission via a satellite transponder

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8913391A GB2232561B (en) 1989-06-10 1989-06-10 Television transmission via a satellite transponder

Publications (3)

Publication Number Publication Date
GB8913391D0 GB8913391D0 (en) 1989-08-02
GB2232561A true GB2232561A (en) 1990-12-12
GB2232561B GB2232561B (en) 1993-06-09

Family

ID=10658243

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8913391A Expired - Fee Related GB2232561B (en) 1989-06-10 1989-06-10 Television transmission via a satellite transponder

Country Status (1)

Country Link
GB (1) GB2232561B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0660545A1 (en) * 1993-12-21 1995-06-28 GRUNDIG E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig GmbH &amp; Co. KG Broadcast signal elaboration system for satellite transmission
EP0695051A1 (en) * 1994-07-29 1996-01-31 Agence Spatiale Europeenne Digital satellite transmission system

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4381562A (en) * 1980-05-01 1983-04-26 Bell Telephone Laboratories, Incorporated Broadcast type satellite communication systems
GB2160064A (en) * 1984-06-08 1985-12-11 Philips Electronic Associated Television transmission system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4381562A (en) * 1980-05-01 1983-04-26 Bell Telephone Laboratories, Incorporated Broadcast type satellite communication systems
GB2160064A (en) * 1984-06-08 1985-12-11 Philips Electronic Associated Television transmission system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0660545A1 (en) * 1993-12-21 1995-06-28 GRUNDIG E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig GmbH &amp; Co. KG Broadcast signal elaboration system for satellite transmission
EP0695051A1 (en) * 1994-07-29 1996-01-31 Agence Spatiale Europeenne Digital satellite transmission system
FR2723279A1 (en) * 1994-07-29 1996-02-02 Agence Spatiale Europeenne DIGITAL SATELLITE TRANSMISSION SYSTEM
US5712850A (en) * 1994-07-29 1998-01-27 Agence Spatiale Europeenne System for digital broadcasting by satellite

Also Published As

Publication number Publication date
GB2232561B (en) 1993-06-09
GB8913391D0 (en) 1989-08-02

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19940610