WO1993000774A1

WO1993000774A1 - Broadcast relay transmission system

Info

Publication number: WO1993000774A1
Application number: PCT/GB1992/001097
Authority: WO
Inventors: Andrew Finney
Original assignee: British Broadcasting Corporation
Priority date: 1991-06-21
Filing date: 1992-06-18
Publication date: 1993-01-07
Also published as: BG98312A; BR9206170A; HU9303550D0; GB2272348A; GB9325098D0; HUT67280A; GB9113394D0; GB2272348B

Abstract

A broadcast television relay transmission system comprises a relay station (16) which receives (17, 18) a TV signal from a parent transmitter (14) and re-transmits it over a relay transmitter (20, 21). Local information e.g. a local weather map may be required to replace the signal from the parent transmitter. To this end a computer (22) has a non-volatile store (23) to store the various components of the weather map, background map and icons etc., and a local studio centre (30) transmits instructions identifying the required picture components and their desired locations. The signal may be transmitted by telephone link (32) and modem (34), or may be included in the signal transmitted by the parent transmitter (14) and downloaded via a receiver/decoder (26). It is thus not necessary to maintain a video bandwidth landline or similar link with the relay station.

Description

BROADCAST RELAY TRANSMISSION SYSTEM

Background of the Invention

This invention relates to a broadcast relay transmission system for use in a broadcasting network, more particularly a television network.

In broadcast television transmitter networks it is often expedient for one transmitter (the relay) to rebroadcast a signal from another transmitter (the parent). In this way a chain of transmitters can be set up without the need for each transmitter to be fed directly from the studio centre by line or radio link.

Whereas in a network it is generally the case that all transmitters will be broadcasting exactly the same signal, there are instances where different material is transmitted from a relay. This is called an opt-out. A district can opt out to allow localised news, weather, travel, advertising or other information to be inserted into the output for a group of transmitters or a single transmitter in the chain.

To achieve this a line-feed of the network signal can be fed through a regional or local studio centre on its way to the distant transmitter. In some cases, however, it might be uneconomic for a studio centre to be set up and/or the topography or topology of the network might make line-feeds uneconomic or even impractical, especially in situations where a very small group of transmitters, or even a single transmitter, would broadcast the material.

Summary of the Invention

The invention is defined in the independent claims appended to this description, to which reference should now be made, and advantageous features of the invention are set out in the claims dependent thereon.

A preferred embodiment of the invention will be described in more detail below in the form of a broadcast television relay transmission system which comprises a relay station which receives a TV signal from a parent transmitter and re-transmits it over a relay transmitter. Local information such as for example a local weather map may from time to time be required to replace the signal from the parent transmitter. To this end the relay station has a computer which stores the various components of the weather map, namely the background map and a variety of icons, and a local studio centre transmits to it descriptors in the form of instructions or codes identifying the required picture components and their desired locations. This data signal may be transmitted by telephone link and mode or may be included in the signal transmitted by the parent transmitter and downloaded by a receiver and decoder at the relay station.

The need to maintain a full video bandwidth link with the relay station is thus avoided.

Brief Description of the Drawings

The invention will now be described in more detail by way of example with reference to the accompanying drawings, in which:-

Figure 1 is a schematic block diagram of a network system embodying the invention; and

Figure 2 illustrates how a local weather map is built up at the relay transmitter in the system of Figure 1.

Detailed Description of the Preferred Embodiment

The broadcast television network 10 illustrated in Figure 1 receives from a main studio a network output indicated at 12 which is transmitted by a transmitter 14. A relay station 16 has a simultaneous broadcast (S/B) or rebroadcast receiver 18 coupled to a receiving antenna 17 and which receives the transmitted network signal. This is then applied to a transmitter 20 having an antenna 21 (diagrammatically shown) which transmits on a different frequency to serve the local area. As thus-far described the system is a typical relay system.

The system illustrated additionally includes at the relay station a computer 22 which receives inputs from a modem 24 and/or from a data receiver 26 which extracts digital data from the signal transmitted by the transmitter 14 and received by the S/B receiver 18. The computer output is added to the signal applied from the S/B receiver 18 to the local transmitter 20 by a switcher/inserter 28. Finally a local control centre 30 is capable of being connected to the modem 24 at the relay station by a dial-up telephone link 32, and/or is similarly connected to modify the network output 12 via a link 34.

The system operates as follows. It is convenient to explain the operation by reference to a specific example, such as a weather map, as shown in Figure 2. It is desired that the relay station 16 transmits at an appropriate time a weather map as shown at (c) in Figure 2, covering just the local area served by the relay station. In a conventional system, a video signal representing the map at (c) is generated at the local control centre 30 and transmitted at full video bandwidth over a land line or the like to the relay station 16. In accordance with the present invention, the various components of the weather map are stored in a non-volatile store 23 diagrammatically shown in the computer 22. These components comprise the local map shown at (a) in Figure 2, and the icons which are to be placed on that map, shown at (b) in Figure 2. To produce the map at (c), an object-oriented data signal is transmitted over the telephone link 32 from the local centre 30 indicating which icons are required on the map, and their locations. The amount of data which needs to be transmitted to the relay station is thus trivially small compared with the full bandwidth video signal previously sent.

The computer 22 receives the instructions to display the map and place the symbols on it at designated co-ordinates. It will be appreciated therefore that neither the symbols nor the map are actually sent from the local centre to the transmitter, but only the display instructions. The computer includes the store for the pictures, picture elements, or text items, and performs the function of a control unit. The control unit controls the reading of the information from the store in response to the data received by the modem, and their location in the picture, and also the combination with the main signal in the switcher/inserter 28. The information can be recalled from the store by interpreting the instructions or codes received by the modem which are related to the individual information items.

The computer on-line local store 23 holds maps of the local area, "sprite"-type images (the display objects) to represent weather features such as cloud, rain, thunder etc., the means to generate a suitable audio commentary (conveniently using text-to-speech or sampled words and phrases), and to display text on the screen, and other elements needed for the building up of a weather forecast. The computer is also able to store the program to control the building up and display of the forecast. There is also means to up-load further programs, sprites, maps and other information (even up to the quality of photographic images) from an outside source using a PSTN (telephone) or PW (private wire) modem, or by decoding information transmitted as data within the TV signal itself. Clearly any downloaded images will have to be sent in advance in slower than real time and stored locally for later transmission.

The system uses readily available narrow band distribution methods to send information to the remote computer facility at the relay transmitter, to enable the computer to build up a suitable display and then insert it onto the air from the relay, replacing whatever is being transmitted at that moment by the parent, and which would otherwise be transmitted by the relay as well. The computer 22 is preferably able to generate both images and sounds, and to control their insertion into the transmitter output stream.

To generate a weather map a remote operator (at HQ, or at a local radio station for example) sends information to the controlling display program in the computer 22 to enable the map to be built up. This information might be of the form:

Show background map of area Place clouds at locations 35,50 30,45 Place lightning bolts at location 32,48 Place text "19" at location 40,40.

This information, if sent in a coded form, can quickly and easily be sent by telephone whereas sending a whole picture would take several minutes. Further commands can be used to animate the display, possibly in real time, and generate an audio commentary if one is needed. Alternatively an audio commentary could be sent using a wide band private wire if one were available, or by sending digitised and/or compressed speech to the relay's computer (22) by the same channel as the display objects.

In an alternative arrangement, the object-oriented data may not be sent by the telephone link 32 from the local centre 30 to the modem 24, but can alternatively be included in the main transmitted signal. In this case the data is sent to the network output by link 34, which may be another dial-up telephone link. Indeed, the dial-up links to the transmitter 14 and the relay station can be used together or as alternatives, depending on circumstances. Data transmitted by transmitter 14 may be included in a teletext or datacast or NICAM audio signal for example, and is extracted at the relay station by the receiver 26 for application to the computer 22. The computer translates the object data into transmission pictures, and if appropriate, sound and the vision and audio signals are applied to the switcher/inserter 28 which applies the network and computer feeds to the relay transmitter 20 under computer control. The system can be used to replace the network output as described above, or to augment it by displaying text superimposed on the network output as, for example, with subtitles. Potential applications include:

News

Weather

Traffic reports

Sports Results

Local advertising

Livestock Market Prices

Lottery Ticket numbers

Emergency messages and information

Avalanche warnings

Local language subtitles in vision.

The data for the system could be distributed by a completely separate diffusion system, such as satellite, or even by hand, with the store being updated manually by someone visiting the station and uploading new data on a regular or occasional basis.

It will be appreciated that the main signal feed to the relay station can be indirect, with a transmitter being fed from a remote receiver by land line or microwave link, as well as having a receiver actually at the distant transmitter site. This may be visualized in Figure 1 by regarding the S/B receiver 18 as being physically spaced from the rest of the relay station.

While the system has been described in terms of a television relay station, the principles may also be applicable to a radio relay station.

By using remote object-based computer techniques, the output of a remote and/or unmanned transmitter can be modified as required. In this way the regionality of a network can be enhanced with a substantially reduced infrastructure cost. High quality, still or animated images can be transmitted from a remote transmitter without the need for a direct clean feed to that transmitter. The invention is thus particularly beneficial where the whole image is to be substituted by the local information, though it is also beneficial in other circumstances where image portions of pictorial information are to be used. The need to transmit the pictorial image portion to the relay station in real time is avoided.

Claims

1. A broadcast relay station comprising: means including a receiving antenna for receiving broadcast signals; a transmitter coupled to the receiving means and provided with a transmitting antenna, for re-transmitting the received broadcast signals; a store containing information to be transmitted as part of the retransmitted signal either combined with or in substitution for the received broadcast signal; signal combining means coupled between the said receiving means and the transmitter and having an input coupled to the output of the store to combine information read from the store with the received signal or to substitute the information read from the store for the received signal; means for receiving a data signal comprising descriptors identifying those information items from the store that are to be transmitted; and control means coupled to the data signal receiving means and the store to control the reading of the information items from the store and their application to the signal combining means.

2. A relay station according to claim 1, in which the store also contains identification codes associated with the individual information items.

3. A relay station according to claim 1 or 2, in which the data signal receiving means comprises a modem.

4. A relay station according to claim 1, 2 or 3, in which the data signal receiving means comprises means coupled to the output of the broadcast signal receiving means to extract therefrom data identifying the information items to be transmitted.

5. A relay station according to any preceding claim, in which the broadcast signal receiving means and the transmitter are capable of receiving and transmitting respectively a television signal.

6. A relay station according to any preceding claim, including means coupled to the broadcast signal receiving means to download transmitted information into the store.

7. A relay station according to any preceding claim, including means for connection to a landline for receiving information to be loaded into the store.

8. A relay station according to any preceding claim, in which the stored information items comprise pictures and/or picture portions.

9. A relay station according to claim 8, in which the descriptors include information as to the desired location of stored picture portions in the transmitted picture.

10. A relay station according to any preceding claim, in which the stored information items comprise audio signals.

11. A video signal transmission unit, comprising: an input for receiving input video signals; an output for providing output video signals; a store containing pictures and/or picture portions; signal combining means having a first input connected to the video signal input, a second input coupled to the output of the store, and an output connected to the video output, to combine pictures or picture portions read from the store with the input video signal or to substitute the pictures or picture portions read from the store for the input video signal; means for receiving a data signal comprising descriptors identifying those pictures or picture portions to be read from the store; and control means coupled to the data signal receiving means and the store to control the reading of pictures and picture portions from the store and their application to the signal combining means.

12. A transmission unit according to claim 11, in which the descriptors include information as to the desired location of stored picture portions in the output video signal.

13. In a broadcast television relay station including a receiver for receiving broadcast television signals and a transmitter coupled to the receiver for re-transmitting the received broadcast television signals, an auxiliary picture generation system comprising: a store containing information to be transmitted as part of the retransmitted signal either combined with or in substitution for the received broadcast television signal; signal combining means having an input to be coupled to the receiver and an output to be coupled to the transmitter, and having a further input coupled to the output of the store to combine information read from the store with the received television signal or to substitute the information read from the store for the received television signal; means for receiving a data signal comprising descriptors identifying those information items from the store that are to be transmitted; and control means coupled to the data signal receiving means and the store to control the reading of the information items from the store and their application to the signal combining means.