GB2146878A - Teletext television receiver with multi-page memory - Google Patents

Abstract

In a television transmission system in which pages of information for display are digitally coded and transmitted during TV line periods not containing normal picture information, the pages as transmitted include both display rows and ghost rows. The ghost rows contain data by which a processor at a television receiver can be controlled to acquire and store in a multi-page memory linked pages which contain information related to that of a page selected by a viewer. These linked pages can be obtained for display directly from the memory, giving the impression of faster page acquisition. The processor displays on an additional self-generated status row of the display, information which identifies the acquired and locally stored linked pages. A remote control keypad is adapted by additional buttons to select either the transmitted pages or the locally stored pages. The figure shows the page format with the page header (R0), display (R1-23), station (upper R24) and ghost (lower R24-R31) rows. <IMAGE>

Description

SPECIFICATION Television systems and receiver arrangements This invention relates to television receiver arrangements of a kind suitable for use in a television transmission system of a character in which coded data pulses representing alphanumeric text or other information are transmitted in a television signal in television lines where no picture signals representing normal picture information are present.

The possibility does exist, for a television transmission system of the above character, of socalled "full-channel" operation in which all of the television lines of each field are employed for transmitting coded data pulses. However, in existing television transmission systems of the above character, only television lines in the fieldblanking intervals are employed for the transmission of the coded data pulses, so that such transmission is, in effect, multiplexed with the normal picture transmission. The alpha-numeric text or other information transmitted in this way can be displayed as a selectable alternative to the normal picture information by the use of a suitably adapted television receiver arrangement which can acquire the coded data pulses from the television signal.A television transmission system of the above character may be of the over-air broadcast type, or of the type which uses a cable as the transmission medium.

A television transmission system of the above character is described in United Kingdom patent specification 1 370 535. Also, the publication "Broadcast Teletext Specification", September 1976, published jointly by the British Broadcasting Corporation, Independent Broadcasting Authority and British Radio Equipment Manufacturers' Association, gives details of a specification for a system of the above character.

In the above-identified Broadcast Teletext Specification, a quantity of message information to be displayed as an entity on a television screen is termed a page and will be so termed hereinafter. All of the pages which are available for display are transmitted in a recurrent cycle, with or without updating page information as appropriate. At the adapted television receiver arrangement a viewer can request any page for display, the requested page being acquired from the cyclic transmission the next time it occurs therein and stored in a display memory of the television receiver until replaced by a subsequently acquired page. A page consists of 24 display rows each having 40 character positions. The first display row (Row 0) of each page is termed a page-header and contains inter alia the page number.The transmission of each page begins with, and includes, its page-header and ends with, and excludes, the next page-header which is transmitted. Thus, it is assumed that all of the display rows which are transmitted between two successively transmitted page-headers belong to the page having the first page-header. The assumption avoids the need to include in each display row data for identifying the page to which the row belongs. However, because, different groups of pages (magazines) use the same range of page numbers, so that more than one page can have the same page number, and because the pages from different magazines may have their display rows interleaved, each display row also includes data which identifies the magazine containing the page that the row belongs to.

The display rows are themselves identified by respective row numbers which are transmitted in the rows and which determine the row positions in the relevant page. This enables the rows of a page to be trensmitted in any order, following the page header for the page, and rows containing no information for display need not be transmitted. The row numbers are provided as respective 5-bit codes.

Because only 24 of the 32 possible 5-bit code combinations are required for identifying the 24 display rows, it has been proposed that at least some of the 10 remaining 5-bit code combinations should be used to identify so-called "ghost" rows in each page. It is the intention that these ghost rows can be used to transmit auxiliary information which is not displayed but which is for processing by logic circuitry in the adapted television receiver arrangement to extend and/or enhance the facilities afforded by the system. Because the information contained in ghost rows is not displayed, it becomes possible to have more than one ghost row with the same row number, provided that each such row contains a sequencing bit or bits to distinguish it from another row or rows having the same row number.In principle, the total number of rows (display and ghost) which a page can contain is then limited by the maximum acceptable period that a viewer has to wait to acquire a requested page from the cyclic transmission of all the available pages.

In order to reduce the acquisition period for a requested page, the use of adapted television receiver arrangements with multi-page display memory storage has been proposed. By this means, a second page can be acquired from the cyclic transmission whilst a first, already acquired, page is being displayed. Once it has been received and stored the second page becomes available for display immediately at the request of a viewer. The need to wait for the requested second page to be acquired, following the request, from the cyclic transmission is thus obviated, giving the impression of faster page acquisition.

It is an object of the present invention to provide in a television transmission system of the character referred to an improved means for controlling the storage and display of a plurality of pages.

According to the invention, the television transmission system comprises transmitting apparatus arranged to transmit all of the pages which are available for display in a recurrent cycle, each page comprising a number of display rows of which the first includes a respective page number and all of which contain respective row addresses, and at least one group of pages in the recurrent cycle being so-called "linked" pages (e.g. in the sense that they contain related information), each linked page including at least one ghost row containing information which identifies other pages in the group; the television transmission system further comprising a television receiver arrangement including, a multi-page memory having a capacity for storing at least some of the pages of the group, page selector means operable under the control of a viewer and having first selection means for selecting for storage and display any page from the recurrent cycle, and processor means responsive to ghost row information of a selected and stored page of a group of linked pages to acquire from the recurrent cycle others of these linked pages for storage in the multipage memory, the processor means being further responsive to display as an additional, status row of the selected page, selection information identifying the linked pages stored in the multi-page memory, the page selector means having second selection means for selecting for display any one of the stored linked pages thus identified.

In the above context, a display row is to be construed to mean a row containing information intended as part of the display of a page with which the display row is identified, and a ghost row is to be construed to mean a row containing information not intended as part of the display of a page with which the ghost row is identified, the information instead relating to that page in some other respect.

In carrying out the invention, the processor means may be still further responsive to ghost row information of a stored linked page which is selected for display, to acquire from the recurrent cycle other linked pages identified by this ghost row information and not already acquired, such other linked pages being stored in the multi-page memory in place of previously stored pages in accordance with some priority as determined by the processor means from the ghost row information, the processor means thereafter re-defining the status row display to provide up-dated selection information identifying the linked pages now stored in the multi-page memory.

Also, in carrying out the invention, in the case where the storage capacity of the multi-page memory is insufficient to store all of the linked pages of a group, the processor means can be responsive to the ghost row information of a selected and stored page of the group to display in the status row other linked pages of the group which have not been acquired and stored, any one of said other linked pages being acquired and stored by the processor means in place of a currently stored linked page, following its selection by said second selection means.

The page selector means is conveniently a combined remote control transmitter and receiver arrangememt of which the receiver is operatively interconnected with the processor means and the transmitter is a hand-held module on which is provided, a first set of numbered push button switches for selecting for display pages from the recurrent cycle by their page number, and a second set of push-button switches for selecting for display pages identified in the status row. Preferably, the push-button switches of this second set have their respective push-buttons visually associated by colour, or otherwise, with respective discrete display regions of the status row at which are identified different linked pages of a group from which a page being displayed has been selected.

In order that the invention may be more fully understood reference will now be made by way of example to the accompanying drawings, of which Figure lisa block diagram of a television transmission system of the character referred to; Figure 2 is a block diagram of a television receiver arrangement of a kind suitable for use in the television transmission system of Figure 1; Figure 3 shows diagrammatically the format of a page of information; and Figure 4 shows diagrammatically the push-button lay-out of a hand-held remote control transmitter module for the purposes of the present invention.

Referring to the drawings, the television transmission system there shown embodies a television receiver arrangement for displaying selectively either a television picture which is produced from picture information in a normal overair broadcast or cable television video signal, or alpha-numeric text or other teletext information which is produced from coded data pulses which are transmitted in the video signal in vertical- or field-blanking intervals thereof. The possibility can also exist for displaying the teletext information concurrently with a television picture, for instance as sub-titles or captions which are superimposed onto the television picture. Furthermore, the system could be adapted for "full-channel" operation, as aforesaid.

As shown generally in Figure 1, the system comprises a television transmitter 1, and a television receiver arrangement 2 which is adapted to receive a television video signal VS via a conventional over-air broadcast or cable transmission link 3. The transmitter 1 includes in known manner means for producing television picture information, means for producing alphanumeric text or other teletext information, and further means for generating the television video signal Vs containing picture signals representative of the picture information and coded data pulses representative of the teletext information, together with the usual synchronising, equalizing and blanking signals which are necessary for the operation of the television receiver arrangement.

The television receiver arrangement 2 comprises the usual amplifying, tuning and i.f. detector circuits at its front end, together with video and data processing circuits as will now be considered with reference to Figure 2.

The television receiver arrangement shown in Figure 2 has its front end 4 connected to receive the incoming television video signal VS. For normal picture display in the television receiver arrangement, where this is provided, the video signal VS is applied to a colour decoder which produces the R, G, and B component signals for the picture display. Time base circuits for the display tube (not shown) would receive the usual line and field synchronising pulses from a sync. separator circuit which extracts these synchronising pulses from the video signal VS. The dotted line element 5 represents these circuit elements which are provided for conventional picture display.

The video signal VS is also applied to another section of the television receiver arrangement which deals with the display of the alpha-numeric text and other teletext information that is received in digitally coded form. This section comprises a video processor circuit 6 which performs inter alia data slicing for retrieving the coded data pulses D from the video signal VS. The video processor 6 also produces regenerated clock pulses C from the data pulses D. The data pulses D are fed together with the clock pulses C to a data acquisition circuit 7 which is operable to feed selected groups D/G of the coded data pulses to a memory 8 for storage therein. A processor 9 is operable in accordance with select signals S applied to it from a remote control arrangement 10 to control which groups of coded data pulses are acquired by the data acquisition circuit 7.The arrangement 10 has receiver part 1 Oa and a remote transmitted part comprising a transmitter lOb and a keypad 1 Oc. The processor 9 is further operable in response to appropriate select signals S from the arrangement 10 to read out from the memory 8 display data for the selected page, for application to a character generator 11 which provides R, G, B component signals for the display of alpha-numeric text and other teletext information. A timing circuit 12 provides timing signals on connections tl to t3 for the circuit elements 7,8 and 11. These circuit elements and the timing circuit 12 are accessed by the processor 9 via an interface circuit 13.

In the television receiver arrangement shown in Figure 2, only single line connections have been shown for the interconnections between the various circuit elements for the sake of simplicity. However, it will be apparent to a person skilled in the art that in practice most of these interconnections would be multi-line. For instance, whereas the coded data pulses D retrieved from the video signal VS would be applied serially to the data acquisition circuit 7 over a single connection, serial-to -parallel conversion would take place within this circuit 7, so that the groups D/G of coded data pulses would be applied to the memory 8 in parallel over a multi-line connection. Also, the connection between the processor 9 and the interface circuit 13 would be a multi/line bus, for instance, a so-called 12C bus.The processor 9 can be a commercially available microcomputer; e.g. from the MAB 8400 Series (Philips).

It is not thought to be necessary for an understanding of the various aspects of the present invention, to be considered next, to give any further specific details for the various circuit elements of the television receiver arrangement.

For the performance of the invention, the transmitter (1 ) of the television transmission system transmits the alpha-numeric text or other teletext information as a plurality of pages of information in a recurrent cycle, with or without updating of the information periodically. Assuming that the above identified Broadcast Teletext Specification defines the basic page format, then each page will have 24 display rows each having 40 characters. This page format is illustrated in Figure 3. The row RO is the page header row, and the rows R1 to R23 are display rows. Each of the rows has 40 character positions C1 to C40. The page header row RO has its first eight character positions C1 to C8 allocated for status purposes, and a page number requested by a viewer may be displayed in these character positions.The next 24 character positions C9 to C32 of the page header row RO are used to display the page number of the displayed page (rolling when the page being looked for), the teletext service name and the date.

The last eight character positions are used to display the time and are therefore always rolling.

The 24 display rows R1 to R23 have their character positions occupied or not occupied in dependence on the information being displayed.

The page format also includes an extra display row R24, termed a status row, which is used to display information generated withjn the television receiver arrangement by the processor 9 as distinct from information generated at the transmitter. This status row R24 has its character positions C1 to C40 defining a plurality of discrete regions, which may vary in number and size for different displays, for identifying pages which are linked (e.g. as regards information content) with the page being displayed.

The references LP1 to LP6 identify typical regions.

The page format, as transmitted, further includes a number of ghost rows R24 to R31 in which auxiliary information can be transmitted by the transmitter. These ghost rows do not form part of a selected page as actually displayed. However, one of these ghost rows (row R30) is, in practice, used in existing systems for transmitting service related data pertaining to the general display and control for the whole system. This row R30 is transmitted once per second by the transmitter and is acquired by the television receiver arrangement regardless of a specific page selection. As mentioned previously, the provision of the ghost rows becomes possible due to the spare 5-bit code combinations that are available from use of the five address bits which are used to identify the row numbers.

The push-button keypad lay-out of a hand-held remote control transmitter module shown in Figure 4 comprises a first set of buttons which are numbered buttons 0 to 9 and a second set of buttons which are lettered R, B, M C and G respectively. For the purposes of the present description these letters refer to the colours red, blue, magenta, yellow, cyan and green respectively. In practice, the lettered buttons would have these respective colours. The shaded portion CB represents an area in which are located other push buttons as normally provided on a television hand-held remote control transmitter module. The particular push-button layout shown is given merely by way of example.

In accordance with the invention, the transmission of the recurrent cycle of pages by the transmitter 1 includes groups of pages which are linked together in the sense that they contain related information. Each of the linked pages of a group includes, as transmitted, a ghost row (assumed to be row R27) containing information which identifies other pages in the group. When a viewer selects a page from the group by keying the page number using the appropriately numbered keys of the keypad 10c, this page is acquired the next time it occurs in the recurrent cycle and stored in the memory 8 from where it is read out for display under the control of the processor 9.The processor 9 also detects that ghost row R27 of the stored page contains the identity of the linked pages and acquires these pages up to the capacity of the memory 8 Assuming that the memory 8 is a 4-page memory, then a maximum of three linked pages can be stored therein at any time, together with the page originally selected. The stored linked pages will, in turn, have a ghost row R27 containing the identity of pages with which they themselves are linked. Also, a further ghost row, for instance, ghost row R25, in each of the stored linked page will contain other software information to which the processor 9 is responsive to identify these pages (e.g. by subject) in respective areas of discrete regions (LP1 to LP6) of the status row R24.These discrete regions are coloured (either background orforeground) in correspondence with the colours of the set of keypad buttons R, B, MY, C and G, and operation of any one of these buttons will cause the processor 9 to display the linked page which is thereby selected in place of the currently displayed page. The ghost row information of the linked page which has been selected for display is then looked at by the processor 9 and other linked pages indentified by this ghost row information and not already acquired are therafter acquired from the recurrent cycle. The processor 9 also provides some priority as to which stored pages should be relinquished so that the newly acquired pages can be stored. The information in the status row R24 is also re-defined by the processor 9 on the basis of the new ghost row information to provide up-dated selection information in the discrete regions (LP1 to LP6).

Claims (8)

CLAIMS:

1. A television transmission system in which coded data pulses representing alpha-numeric text or other information are transmitted in a television signal in television lines where no picture signals representing normal picture information are present, the system comprising transmitting apparatus arranged to transmit said information in pages all of which are available for display in a recurrent cycle, each page comprising a number of display rows of which the first includes a respective page number and all of which contain respective row addresses, and at least one group of pages in the recurrent cycle being linked pages, each linked page including at least one ghost row containing information which identifies other pages in the group; the television transmission system further comprising a television receiver arrangement including, a multi-page memory having a capacity for storing at least some of the pages of the group, page selector means operable under the control of a viewer and having first selection means for selecting for storage and display any page from the recurrent cycle, and processor means responsive to ghost row information of a selected and stored page of a group of linked pages to acquire from the recurrent cycle other of these linked pages for storage in the multi-page memory, the processor means being further responsive to display as an additional, status, row of the selected page, selection information identifying the linked pages stored in the multi-page, memory, the page selector means having second selection means for selecting for display any one of the stored linked pages thus identified.

2. For use in a television transmission system as claimed in Claim 1, the television receiver arrangement including, a multi-page memory having a capacity for storing at least some of the pages of the group, page selector means operable under the control of a viewer and having first selection means for selecting for storage and display any page from the recurrent cycle, and processor means responsive to ghost row information of a selected and stored page of a group of linked pages to acquire from the recurrent cycle others of these linked pages for storage in the multi page memory, the processor means being further responsive to display as an additional, status, row of the selected page, selection information identifying the linked pages stored in the multi-page memory, the page selector means having second selection means for selecting for display any one of the stored linked pages thus identified.

3. A television receiver arrangement as claimed in Claim 2, characterised in that the processor means is responsive to ghost row information of a stored linked page which is selected for display, to acquire from the recurrent cycle other linked pages identified by this ghost row information and not already acquired, such other linked pages being stored in the multi-page memory in place of previously stored pages in accordance with some priority as determined by the processor means from the ghost row information, the processor means thereafter re-defining the status row display to provide up-dated selection information identifying the linked pages now stored in the multi-page memory.

4. A television receiver arrangement as claimed in Claim 2 or Claim 3, characterised in that in the case where the storage capacity of the multi-page memory is insufficient to store all of the linked pages of a group, the processor means is responsive to the ghost row information of a selected and stored page of the group to display in the status row other linked pages of the group which have not been acquired and stored, any one of said other linked pages being acquired and stored by the processor means in place of a currently stored linked page, following its selection by said second selection means.

5. A television receiver arrangement as claimed in any one of Claims 2 to 4, characterised in that the page selector means is a combined remote transmitter and receiver arrangement, of which the receiver is operatively interconnected with the processor means and the transmitter is a hand-held module on which is provided, a first set of numbered push button switches for selecting for display pages from the recurrent cycle by their page number, and a second set of push-button switches for selecting for display pages identified in the service row.

6. A television receiver arrangement as claimed in Claim 5, characterised in that the push-button switches of said second set have their respective push-buttons visually associated by colour, or otherwise, with respective discrete display regions of the status row at which are identified different linked pages of a group from which a page being displayed has been selected.

7. A television transmission system, having a television receiver arrangement substantially as hereinbefore described with reference to the accompanying drawings.

8. A television receiver arrangement for the system claimed in Claim 7.