Currently, the most common arrangement for accessing information networks such as the Internet comprises a browser application operating on a personal computer (PC), and with retrieved data content, such as web pages, being displayed on a monitor coupled to the PC. However, it is also known to provide an arrangement comprising a browser application operating in conjunction with a television or video receiver, with the retrieved data being displayed on the display of a television which is either integral with or coupled to the receiver.

The use of a browser in conjunction with a television receiver produces opportunities for presenting and using Internet content in relation to the content of broadcast television programmes. The various opportunities offered are generally termed interactive

television experiences. The ATVEF specification specifies content format and delivery mechanisms for these, enabling Internet related (i. e. HTML-enhanced) television content to be broadcast across any broadcasting network to any ATVEF compliant receiver.

One particular interactive facility that is known is the inclusion, in broadcast video signals, of a"trigger" containing a universal resource locator (URL) (sometimes referred to as a uniform resource locator) or website address. The trigger is recognised by the television receiver and in response to a user input, the browser will log on to the Internet and access the URL.

In order to access the website associated with the URL, the browser sends the URL (specifically the URL up to the top-level domain name-e. g.. com or. co. uk-not including anything to the right of this-e. g./radio4) to a Domain Name System (DNS) server. The DNS server looks up the associated Internet Protocol (IP) address of the server on which the website associated with the URL is hosted and sends this back to the browser. The browser then sends the URL (including anything to the right of the top-level domain name) to the specified IP address. The host server then processes the received URL and transmits the appropriate website data to the browser.

Generally, such a facility enables viewers to be provided with easy access to websites whose contents are related to the contents of the television programmes the viewers are currently watching. For example, viewers can be directed to a website associated with a particular television advertisement, or to a website containing more

information relating to a documentary programme.

It is noted that the terminology"programme"and "television programme", as used in this specification, is not restricted to any particular content or structure of content, and hence includes items such as advertisements, live news or sports broadcasts, previews and so on.

A protocol conventionally employed for processing such triggers is defined in Section 1.1.5 of the above mentioned ATVEF specification for receipt of triggers contained in an analogue broadcast format, in particular where the data defining a trigger is provided in a vertical blanking interval (VBI) line of an analogue video signal.

Various disadvantages and limitations arise with receiver/browser arrangements provided to date within the framework of the ATVEF specification. Moreover,"in the clear"transmission of the explicit URL information as part of the trigger removes areas of control from either the broadcaster of the television programmes or the Internet service provider providing Internet access to the receiver/browser apparatus. Because the receiver/browser apparatus will respond to direct URL information contained in the broadcast programmes, end users will be directed to website addresses provided by the suppliers of the programmes without the consent of the broadcaster of the programmes or the Internet service provider. Also it is not possible for the broadcaster or the Internet service provider of the receiver/browser apparatus to control the time when end users access the indicated websites. These disadvantages arising from the lack of control are magnified when present arrangements

are applied to digital video broadcasts rather than analogue broadcasts, since the increased levels and forms of interaction rendered possible by the increased data content of digital broadcasting are diluted or reduced by such inflexibility and lack of control.

In a first aspect the present invention provides a broadcast system which enables link data provided with a broadcast programme to be forwarded to a redirect server which can determine from the link data a website address which corresponds to the broadcast programme.

In a second aspect the present invention provides a broadcast system which inserts link data including index values into programme feeds, and provides look-up tables of the index values cross-referenced to website addresses to a redirect server, and means for broadcasting the programme feeds including the link data to a user apparatus, the user apparatus comprising means to recognise and extract the link data with respect to a programme being displayed on a television screen by the user apparatus, and for prompting the user to enter a command in response to which the user apparatus transmits the index value to the redirect server, the redirect server being arranged to compare the index value with its look-up table and reply to the user apparatus with the corresponding website address such that the user apparatus can then call up the indicated website address.

In a further aspect, the present invention provides a broadcast receiver and Internet browser arrangement which accesses websites on the Internet which are associated with broadcast programmes received by the broadcast receiver, by means of extracting identity data

included in the broadcast signal and forwarding the identity data to a look-up table which provides the required website address.

In a further aspect the present invention provides a system for managing the scheduling of link data or trigger data for insertion into programme feeds, and corresponding provision of the link data or trigger data to a server, such that the trigger data or link data included in a multiplex broadcast can be employed by end users to access the trigger data or link data in the server, thereby determining the identity of a website address linked to a broadcast programme.

The present invention also provides a digital datastream generated by a broadcast system in accordance with the above described first and second aspects of the invention.

The present invention advantageously provides a form of video broadcast/Internet access interaction that can require involvement of the broadcaster or Internet service provider in the process for accessing the websites, as the need to broadcast explicit URL information in the clear is removed. The present invention therefore allows a broadcaster or other operator to have a greater level of control over the way in which end users access the Internet, including a greater level of control over which portal the end user goes through, the timing of the end user's access to the Internet, and indeed which website addresses may be included in the triggers. The present invention further allows an optional facility in which different end users can be directed to different website addresses in

response to a common trigger.

Throughout, the term public address will be used to refer to an address such as a URL, in the clear, or an IP address which can be used by any conventional browser connected to the Internet to access a specified website.

By contrast, the term trigger index refers to a code which must first be de-coded into, or replaced with, a public address in order for a browser to access the associated website in a conventional manner.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of a video broadcast/Internet access system; Figure 2 is a block diagram illustrating a system for providing a trigger data/website address look-up table to a redirect server and for inserting trigger data into broadcast data; Figure 3 illustrates the contents of a trigger data/website address look-up table; Figure 4 is a block diagram illustrating a separate receiver and browser; Figure 5 shows the processing operations performed by the receiver and browser illustrated in Figure 4 and a redirect server; Figure 6a illustrates contents of a look-up table including browser serial number data; and Figure 6b is a further look-up table including browser serial number data.

Figure 1 is a schematic illustration of a video broadcast/Internet access system according to a first

embodiment of the invention. By way of example, one receiver/browser apparatus 2 is shown, although in practice many more receiver/browser apparatus are included in the system.

The receiver/browser apparatus 2 comprises an antenna 4 for receiving a broadcast signal 6 transmitted by a transmitter 8 at RF frequencies, and the receiver/browser apparatus 2 is connected to a television 10 for displaying received programmes. In the present embodiment, the broadcast signal 6 is in a digital format and comprises a multiplexed datastream containing various television programmes formatted according to the MPEG-2 standard and broadcast in accordance with the DVB standards. The receiver/browser apparatus 2 is arranged to receive and process the broadcast signal 6 in conventional manner in compliance with the DVB standards, so as to provide an analogue video output to a conventional analogue television 10.

The receiver/browser apparatus 2 additionally functions as an Internet browser. With respect to this function an end user employs a user input means 12 to perform conventional user control operations such as inputting instructions to log on to the Internet and inputting specific uniform resource locators (URLs) or website addresses. In the present embodiment the user input means 12 comprises an infrared keyboard arranged to communicate with an infrared sensor in the receiver/browser apparatus 2, as will be explained in further detail below with reference to Figure 4. Also, retrieved Internet content is displayed on the television 10.

When the receiver/browser apparatus operates as a browser, it connects to the Internet 18 via a public switched telephone network (PSTN) 14 and an Internet service provider (ISP) 16.

When the browser is operating in conventional mode, the user inputs a website address (i. e. URL) using the user input means 12 and the receiver/browser apparatus 2 logs on to the ISP 16 and accesses a website server W1, W2, W3 providing the website. In response the website server W1, W2, W3 transmits web page data back to the receiver/browser apparatus 2 in conventional fashion.

The present embodiment provides an additional way in which URLs (i. e. website addresses) served by specific website servers W1, W2, W3 are accessed. Trigger data related to a programme being broadcast is also included in the broadcast signal 6. The receiver/browser apparatus 2 detects the trigger data and adds an icon and a text prompt on top of the television picture. In response to the added icon and/or text, the user can enter or affirm an instruction for the receiver/browser apparatus to access the Internet.

In the present embodiment the trigger data contains a trigger index value. In response to the user's input, the receiver/browser apparatus 2 employs its browser mode to access a redirect server 20 by logging on to the ISP 16 via the PSTN 14. The redirect server contains look-up tables in which trigger index values are associated with specific website addresses. The trigger index/website address look-up table at the redirect server is provided so that when a user responds to the trigger data during a particular television programme, he

can ultimately be connected to a website address that is associated with the content of that television programme.

(To this end, in the present embodiment, the provision of the look-up table to the redirect server 20 and the incorporation of the trigger data into the broadcast signal 6 are jointly managed by a common trigger schedule controller, as will be described in more detail below with reference to Figure 2. It will be appreciated from the above that the trigger data forms link data linking a broadcast programme and a specific website). The redirect server 20 sends the appropriate website address specified by the look-up table back to the receiver/browser apparatus 2, which then automatically accesses the corresponding website server W1, W2, W3 via the PSTN 14, ISP 16 and Internet 18.

Figure 2 shows a block diagram illustrating an arrangement for providing a trigger data/website address look-up table 42 to the redirect server 20 and for incorporating corresponding trigger data T1, T2 into a multiplexed broadcast datastream 36 provided to the transmitter 8 for broadcasting as the broadcast signal 6.

In the present embodiment a broadcasting organisation (hereinafter referred to as the broadcaster) receives programme feeds from a plurality of different service providers, including service providers S1 and S2 as shown by way of example in Figure 2. The broadcaster maintains overall control of the allocation and scheduling of trigger data using a trigger schedule controller 32.

The trigger schedule controller 32 formats the content of trigger data T1 and forwards it to the service

provider S1 for incorporation into a programme feed. In the present embodiment, the trigger data is of the following form: <trigger index value> [n: text string] [e : expiry date and time] (checksum) The letter"n :" indicates that a name field is to follow and the text string inserted in the name field was, in the present embodiment, specified by the service provider S1 and notified in advance to the broadcaster.

This text will later be displayed to the end user. In the case of the trigger data T1, the text says"hit Return to find out more via the Internet".

The letter"e :" indicates a date/time field is to follow. The value of the date/time inserted in this field specifies an expiry time and date which will later be used by the receiver/browser apparatus 2 on receipt of the broadcast signal 6 to determine whether the trigger data is still valid at the time of receipt. In the present embodiment this value is input by the broadcaster, using knowledge of the intended time of broadcast of the corresponding television programme. By controlling specification of the expiry time and date, the broadcaster can ensure, for example, that a first trigger expected to lead to a high level of use of the redirect server 20 expires before a second trigger also expected to lead to a high level of use of the redirect server 20 is transmitted.

The trigger index value is a twelve digit number allocated by the broadcaster to the particular trigger data T1. The trigger index value will later be used by the redirect server to determine which website the

receiver/browser apparatus 2 should ultimately access, as will be explained in more detail below.

In the present example, the trigger index value allocated to the trigger data T1 is the value 123456789123.

The"checksum"is an error check value used to allow the receiver/browser apparatus 2 to check whether the trigger data it receives has been corrupted before receipt. The protocol for the checksum is identical to that used in the Internet Protocol and is further explained in section 1.1.5 of the ATVEF specification.

The text string, expiry date/time and checksum constituents of the trigger data are all formatted as specified in section 1.1.5 of the ATVEF specification. It is, however, noted that the complete string of the trigger data as described above does not strictly comply with section 1.1.5 of the ATVEF specification as it contains the twelve-digit trigger index value rather than a URL as such.

The service provider S1 injects, i. e. embeds, the trigger data T1 into a serial digital interface (SDI) video stream containing the television programme to be broadcast. In the present embodiment, the video stream is in an uncompressed full broadcast digital video format known as CCIR 601, which uses a bit stream on a single carrier. Particular portions of respective samples within the bit stream correspond respectively to video or audio content, and positions within the video portion of the bit stream broadly correspond to particular lines of the PAL analogue video format. In the present embodiment, the trigger data is inserted into the video

part of the bit stream that corresponds to one of the vertical blanking interval (VBI) lines specified in PAL.

In the present embodiment, the trigger data is inserted in correspondence to the required VBI line pursuant to the ATVEF specification, so that the receiver/browser apparatus 2 can later employ the ATVEF protocols to extract the trigger data, as will be explained in more detail below with reference to Figures 4 and 5. The service provider S1 injects the trigger data into the programme bit stream using a"data bridge"as is conventionally used to inject, for example, sub-titling to television programmes.

The resulting bit stream including the trigger data forms a programme feed Pl which the service provider Sl feeds to a multiplexer/MPEG-2 encoder 38, which multiplexes different programmes to be broadcast. In the present embodiment the multiplexer/MPEG-2 encoder 38 is operated by the broadcaster.

The above operations are repeated in the case of separate trigger data T2 for a further service provider S2 so as to provide a programme feed P2 including the trigger data which is forwarded to the multiplexer/MPEG-2 encoder 38. The trigger index value for the trigger data T2 is 891234567891.

The multiplexer/MPEG-2 encoder 38 is operated in conventional fashion in compliance with the MPEG-2 standard and the DVB standard. As is well known to the person skilled in the art, the multiplexer/MPEG-2 encoder 38 extracts separate elementary datastreams from each programme feed. The multiplexer/MPEG-2 encoder encodes

the data according to the relevant specification in the MPEG-2 standard, i. e. according to the type of elementary datastream (video, audio or other). The multiplexer/MPEG- 2 encoder also allocates, to each extracted elementary datastream, a respective packet identification code (PID). The multiplexer/MPEG-2 encoder 38 further compiles a hierarchy of look-up tables comprising a programme association table (PAT) and a programme map table (PMT).

In the present embodiment, the broadcaster uses a set-up menu of the multiplexer/MPEG-2 encoder 38 to specify that for programme feed P1 the data held in the specified VBI line, i. e. the trigger data T1, is to be extracted, encoded as per the DVB specification for teletext data, and allocated a separate PID (i. e. the multiplexer/MPEG-2 encoder 38 effectively takes the trigger data T1 from the VBI line and translates it into DVB teletext data on a separate PID). The broadcaster carries out the same procedure for the programme feed P2.

The multiplexer/MPEG-2 encoder 38 forms a multiplexed broadcast datastream 36, which is in packetised form with each packet of data identified by means of the above mentioned PIDs and forwards the multiplexed broadcast datastream 36 to the transmitter 8 for broadcasting as the broadcast signal 6.

When the service providers Sl and S2 provided the advance notification of their respective trigger data Tl and T2 to the broadcaster, they also indicated the website addresses that are to be associated with the trigger data. These website addresses are entered by the broadcaster into the trigger schedule controller 32 which produces a look-up table 42. The trigger schedule

controller 32 forwards the look-up table 42 to the redirect server 20.

Figure 3 shows the contents of the look-up table 42.

The table associates each trigger index value 92 with a website address 94 that has been specified for it. As shown, the trigger index value 123456789123 from the trigger data T1 is associated with the website address www. abcwl. com, which is the website address served by the website server W1, and which in the present embodiment is commercially linked with an advertiser whose advertisement forms the programme feed from service provider S1. Similarly, the trigger index value 891234567891 from the trigger data T2 is associated with the website address www. xyzw2. co. uk which is served by the website server W2 and which provides content related to the television programme being supplied by the service provider S2.

Thus, referring back to Figure 1, it can be appreciated that a given trigger index value included in a specific television programme being broadcast as part of the broadcast signal 6 is associated with a specific website address as specified in the look-up table which can be accessed at the redirect server 20.

Further details of the receiver/browser apparatus 2 will now be described with reference to Figure 4. The receiver/browser apparatus 2 comprises a separate receiver 50 and browser 52. The receiver 50 includes the following items coupled in series as shown: the antenna 4, a tuner 54, a demodulator 56, a demultiplexer 58, an MPEG decoder 60 and a digital to analogue converter 62.

The digital to analogue converter 62 provides an output

to the browser 52 via a SCART connection 64.

In operation, the broadcast signal 6 is received by the antenna 4 and input to the tuner 54. The tuner 54 tunes to the appropriate RF frequency enabling it to forward the tuned signal to the demodulator 56. The demodulator 56 demodulates the broadcast multiplexed datastream from the RF carrier frequency.

The demodulated multiplexed datastream is passed to the demultiplexer 58 which, under the control of a microprocessor (not shown) demultiplexes the datastream using the PMT and PID data contained in the datastream in accordance with the DVB standard. Thereafter, the demultiplexed signal is passed to the MPEG decoder 60 for decoding and then onto the digital to analogue converter 62 where the data is converted into an analogue video signal for transmission over the SCART connection 64 to a video processor 66 of the browser 52. The video processor 66 is also coupled by a further SCART connection 68 to the television 10.

The browser 52 also comprises a central processing unit (CPU) 64 coupled to the video processor 66. The CPU 64 is also coupled to a memory 70, a modem 72 and an infrared sensor 74. The infrared sensor 74 is for receiving infrared signals 76 from an infrared keyboard 78. The modem 72 is coupled via a telephone line 80 to the PSTN 14.

In operation, the video processor 66 compiles the final video signal that is sent over the SCART connection 68 for presentation by the display of the television 10.

The video processor 66 operates under the control of the CPU 64. When the CPU 64 is operating in browser mode, it

may for example instruct the video processor to display specific website data over the analogue video data that the video processor 66 is receiving from the receiver 50.

However, in the absence of any such override instructions, the video processor simply forwards the analogue video data it is receiving from the receiver 50 to the television 10 for display.

The CPU 64 operates in a full browser mode by implementing and controlling a conventional Internet browser application. Accordingly, the modem 72 serves as a conventional modulator and demodulator of data to be transmitted and received over the telephone line 80 to the PSTN 14 and onto the Internet. The memory 70 stores algorithms and data employed by the CPU 64. Website pages received by the browser 52 are allocated. to the video processor 66 to be displayed on the television 10.

The infrared sensor 74 receives user inputs for browsing instructions from the infrared keyboard 78.

In addition, the browser 52 reacts to the trigger data contained in the broadcast signal 6, as will be described in more detail below with reference to Figure 5.

The above described arrangement of a separate receiver 50 and browser 52 allows a browser adapted to respond to trigger data contained in an analogue video signal to be operated in conjunction with a broadcast receiver 50 adapted to receive digital video broadcast.

This further allows use of the ATVEF specification for detecting and processing triggers, which is specified in terms of analogue video, with trigger signals transmitted as part of a DVB broadcast.

Figure 5 shows the processing operations performed by the receiver 50, browser 52 and redirect server 20 in this embodiment. At step S40 the receiver 50 receives and processes the broadcast signal 6. The procedure for processing the basic video and audio content of the received broadcast signal 6 was described earlier with reference to Figure 4. How this procedure is further adapted to process the trigger data content in the present embodiment will now be described in further detail for the trigger data Tl included in the programme feed Pl.

As was described above, the trigger data Tl is included in the broadcast signal 6 in the form of DVB teletext data with its own PID allocated thereto. The demultiplexer 58 extracts the trigger data on the basis of this PID value. The MPEG decoder then decodes the trigger data employing the usual protocol specified in the DVB standard for DVB teletext data. The decoded signal is forwarded to the digital to analogue converter 62, which converts the signal into analogue video format.

The trigger data is again located in the VBI lines.

At step S44 the receiver 50 feeds the analogue video signal from the digital to analogue converter 62 via the SCART connection 64 to the video processor 66 of the browser 52.

At step S48, the video processor 66 analyses the analogue video signal, and detects whether any data is presently in the VBI lines. If the video processor 66 indeed detects trigger data in the VBI lines, then at step S52 the video processor 66 extracts the data and passes it to the CPU 64.

At step S56 the CPU 64 checks the validity of the trigger data passed to it by the video processor 66. The CPU 64 checks the checksum value contained in the trigger data T1 against a checksum algorithm stored in the memory 70. The CPU 64 also checks the expiry date and time contained in the trigger data with its own system clock and data.

Provided that the checksum is correct and the expiry date and time of the trigger data has not been exceeded, then at step S60 the CPU 64 retrieves a video display page stored in the memory 70. This video display page is essentially a transparent page except for an icon on it.

The CPU 64 forwards this page to the video processor 66.

The CPU 64 also extracts the text data from the text field of the trigger data, and forwards the extracted text data to the video processor 66. As a further part of step 60, the CPU also extracts the trigger index value from the trigger data and places this value in the memory 70.

At step S64 the video processor 66 overlays the transparent page containing the icon and the extracted text data onto the analogue video signal it is receiving over the SCART connection 64. At step S68, the video processor 66 feeds the analogue video signal plus the overlaid icon and text over the SCART connection 68 to the television 10. At step S72 the television 10 continues to display the current programme as contained in the analogue video signal but with the above described icon and text overlaid on the picture.

It is noted that the overall receiver and browser arrangement has thus been triggered into a form of

browser mode, as it is now providing an Internet-access related function to the end user rather than merely processing a television programme.

As was described earlier the text data of trigger data T1 says"hit Return to find out more via the Internet". In the present example the end user who is watching the programme decides he would indeed like to find out more information, and therefore he hits the Return key on the infrared keyboard 78. The resulting input to the infrared sensor 74 is detected by the CPU 64, i. e. at step S76 the CPU 64 receives the user input.

In response, at step S80 the CPU 64 retrieves the trigger index value from the memory 70, and appends it to the website address of the redirect server which the CPU 64 also retrieves from the memory 70. In the present embodiment, the trigger index value is 123456789123. In the present embodiment the URL of the redirect server is www. redirect-server. com. The URL plus appendage is therefore www. redirect-server. com/123456789123.

At step S82, the CPU 64 activates the browser application and calls up the redirect server using this appended URL after logging on to the ISP 16 via the modem 72 and the PSTN 14. This browser operation, and the resulting routing of the connection to the redirect server 20 from the ISP 16 is implemented in conventional fashion, since the above-described URL plus appendage is consistent with conventional URL protocols, where appended data following the"forward slash"normally indicates a sub-page of an initial website.

The redirect server 20 is however programmed to recognise the appended data as a trigger index value

rather than a sub-page, and at step S84 the redirect server extracts the trigger index value and compares it to the trigger index values 92 in the look-up table 42, thereby identifying the associated website address which is www. abcwl. com.

At step S88 the redirect server replies to the CPU 64 informing the CPU 64 of the identified website address, namely www. abcwl. com. At step S92, the CPU 64, which is already operating in browser mode, automatically calls up the identified website address www. abcwl. com via the modem 72, the PSTN 14, the ISP 16 and the Internet 18.

The website server W1 then responds in conventional manner by supplying the contents of a web page to the CPU 64 which forwards the web page to the video processor 66 for display on the television 10. The CPU 64 then continues to operate the browser 52 in conventional browser mode.

In the above embodiment the look-up table 42 simply associates a respective single website address with each trigger index value. In an alternative embodiment of the present invention, a single trigger index value can instead be associated with more than one website address, as follows. Each receiver/browser apparatus 2 is identified by means of a unique serial number. This serial number is held in the memory 70 of the respective browser 52. Different end users are allocated browsers 52 with different specified serial numbers in accordance with a commercial criteria. In particular, serial numbers less than 4,000,000 have been allocated to one group of end users, and serial numbers over 4,. 000,000 to another

group. The service provider S2 specifies different web site addresses according to different serial numbers. As shown in Figure 6a, in the present embodiment the look-up table 42 contains, in association with the trigger index value 891234567891, different website addresses for serial numbers less than 4,000,000 and serial numbers greater than 4,000,000.

When the URL of the redirect server 20 and its appendage, (i. e. www. redirect-server. dom/891234567891) is forwarded to the redirect server via the ISP 16, the redirect server is also informed of the serial number of the browser 52 by the ISP 16. The ISP 16 previously acquires knowledge of the serial number of the browser 52 when the browser identifies itself by the serial number during an initial procedure of logging on to the ISP 16.

Thus, a browser of serial number less than 4,000,000 is connected to the website address www. xyzw2. co. uk served by the website server W2, whereas a browser of serial number greater than 4,000,000 is connected to the website address www. xyzw3. co. uk served by the website server W3.

In a further variation, instead of the look-up table containing serial number ranges, the serial numbers are divided into specific serial number categories which are included in the look-up table 42. For example, Figure 6b shows a look-up table 42 in which two categories of serial number are catered for. In this example each trigger index value 92 has a separate website address entry 94 for each serial number category 98, although, this can be a duplicate, i. e. in the example shown in Fig. 6b the service provider related to the index value

123456789123 has no reason to distinguish according to the serial number category of the browser, and hence the same website address is provided for both serial number categories 1 and 2.

The use of serial number categories allows greater flexibility in the issuing of serial numbers, or of handling already allocated serial numbers, since a separate look-up table can be provided to the redirect server 20 for indicating which serial numbers are allocated to which category, and this can easily be updated.

In each of the above embodiments where website addresses can be varied according to serial number, a range of commercial and other advantages result. One possibility is for the serial numbers to be distributed according to an estimate or measure of the spending power of the end user. In this case website addresses can be allocated to the different serial numbers, for example, so that they relate to ranges of products at prices most likely to be of interest to the corresponding end users.

Another possibility is for the serial numbers to be organised on a geographical basis, in which case different website addresses relating to, for example, shops in different geographical areas could be employed.

Yet another possibility is that the serial numbers could be allocated according to the type or capability of the individual browsers 52, and the associated website addresses could be specified according to the technical compatibility of their content in relation to the capabilities of the various browser types.

Also, different website addresses may be specified

dependent upon the serial numbers, for a given trigger index value, for the purpose of reducing the number of users accessing a single website, i. e. to avoid website server overload. In this case, the same webpage content may be provided from the different website addresses/website servers. Moreover, this load reduction benefit may be achieved as an additional benefit when different website addresses are specified for a single trigger index value for the other purposes described above.

In the above embodiments employing the serial number of the receiver/browser apparatus, the serial number can be any form of unique identifier or class identifier of the apparatus which can be processed by the redirect server.

In the above embodiments, the expiry time and date entered in the date/time field of the trigger data is a specific time and date. If the CPU of the browser receives the trigger data after the specified expiry time and date, then it does not consider the trigger data to be valid and the prompt is not displayed to the user.

This arrangement is suitable for programmes that are to be broadcast once only, and at a predetermined time and date. In other embodiments, it is necessary to accommodate the repeat transmission of a programme, such repeated transmission being either during one given day or for repeat a number of days or months later. One way of accommodating the repeated transmissions during one given day is to set the expiry time at twenty three hours, fifty nine minutes and 59 seconds of the given day. In order to accommodate the scenario of a repeat at

a later date, an alternative embodiment can be employed in which expiry dates are not included in the trigger data and the CPU of the browser is not required to check for such an expiry date. Alternatively, a code can be included and the CPU programmed to recognise the code as eliminating the requirement for the expiry date to be checked.

In the above embodiments, the trigger index value is a twelve digit number. In other embodiments, any other suitable format can be employed.

In the above embodiments, trigger data was supplied to individual service providers who injected the trigger data into respective programme feeds. In other embodiments, service providers inform the broadcaster of the timing of particular programmes, and the broadcaster, rather than the service provider, injects the trigger data into the programme feeds when they are later received from the service providers.

Also, in other embodiments, trigger data can be incorporated at the time of original production of a programme, thus obviating the later need to insert trigger data.

More generally, it is to be appreciated that the present invention can be applied to broadcast systems and arrangements other than that shown in Figure 2, including systems and arrangements comprising different component parts and/or different interconnections, and commercial or operational interactions, compared to those shown in Figure 2. As such, the present invention is not limited according to which technical means or commercial arrangement of a broadcasting system is employed to

coordinate and insert trigger data into programme feeds, broadcast the programmes, compile the look-up tables, and so on.

In the above embodiments the trigger data was included in the multiplexed broadcast datastream in the form of DVB teletext data to which a specific PID was allocated. In an alternative embodiment which nevertheless remains in compliance with the DVB standard, the trigger data is included in the multiplexed broadcast datastream in the form of DVB specified"private data" packet. In this case the MPEG decoder of the receiver is programmed to decode the particular content of the private data packet and adds appropriate VBI headers and footers so that the data can be detected by the video processor 66 of the browser 52.

In the above embodiments, the URL of the redirect server is input into the memory of the browser during manufacture. In other embodiments, the URL of the redirect server can be downloaded via the telephone connection or the broadcast connection under control of the CPU of the browser. An existing URL of the redirect server may be updated in this way.

In the above embodiments, the receiver/browser apparatus included a separate receiver complying with the DVB standard and a separate browser adapted to detect trigger data provided to it in the form specified by the ATVEF specification. In other embodiments, different combinations of analogue/digital broadcasting technology can be employed. For example, the browser can be adapted to recognise digital forms of the trigger data directly, i. e. not relying on the ATVEF specification or VBI lines.

In this case, a separate receiver and browser may still be employed or, alternatively, a single MPEG or other digital video receiver and browser module could be employed. In yet further embodiments the television can be integrated with either the receiver, the browser or a combined receiver and browser module.

In other embodiments, digital video broadcasting protocols other than DVB or MPEG-2 can be employed.

In yet further embodiments, the television programmes and trigger data can be broadcast in analogue format. In this case, when continuing to use the ATVEF specification, the trigger data can be broadcast directly in the VBI lines.

In the above embodiments, the programme feeds and data signals were broadcast to the receiver by means of terrestrial RF broadcasts. In other embodiments such broadcasts can be performed by satellite broadcast, or over a cable network. Furthermore, two or more of terrestrial, satellite or cable broadcasting can be employed in combination.

In the above embodiments the receiver/browser apparatus was coupled to the ISP via a PSTN. In other embodiments any suitable connection can be employed, including for example a digital subscriber line (DSL).