DE3937653C2 - - Google Patents

Description

The invention relates to a method according to the Preamble of claim 1. Such a Ver driving is known from GB 21 87 614 A.

In the conventional teletext system currently used in Europe (with the exception of France), only the so-called "level 1" of the teletext standard WST (world system teletext) is used, which has only a limited basic character set for texts and graphic representations . Special characters, fine structures or shades of color cannot be reproduced with this "Level 1" system. To avoid these shortcomings, the WST standard, particularly in its "Level 2" and "Level 3" versions, provides for the transmission of supplementary data in so-called pseudo-rows (also called "ghost rows"), which are not used by "Level 1" , but wear addressable row numbers that are kept in the transmission format. If necessary, several rows with the same row number must be used to transmit the necessary amount of supplementary data, as illustrated with the aid of FIG. 1 for row number # 26 (cf. "Broadcasting Communications" 27th vol. (1983), No. 3, p . 116 to 134). For special supplementary data, namely for freely definable characters (DRCS characters = dynamically redefinable character sets), pseudo-pages inserted in the teletext cycle with hexadecimal numbering are also used in accordance with the WST standard or GB 21 87 614 A, which format (rows 0 -23) have an extended format (rows 0-24) and only contain information about the bit structure of the DRCS characters. The respective display mode ("mode") of the DRCS characters is specified in a pseudo row (row 28) on each pseudo page. The position of the character spaces in the basic page, which are to be supplemented by means of the DRCS characters, and the address of the relevant DRCS character in the pseudo page are specified in the pseudo row 26 of the relevant basic page. Furthermore, the page number of the assigned pseudo page is specified in the pseudo row 27.

Due to the division of information for structure, Display type and addressing of the supplementary data Pseudo-series and pseudo-pages is the known method not just limited to DRCS characters, but proves itself to be cumbersome and prone to failure.

Regardless of whether just pseudo-series alone or pseudo rows and pseudo pages are transferred together the problem that the teletext receiver has no information about the number of teletext pages (reason data) transferred pseudo series. The decoder "white" therefore not whether, which and possibly how many pseudo-rows have been sent out to a teletext page. A correct evaluation can therefore only take place if  the desired teletext page and all assigned Pseudo-rows can be received completely. Furthermore, must in the decoder for each teletext page to be stored an additional storage space, e.g. B. 4 kbyte, constantly available, which at feh lender transfer of pseudo series not otherwise is usable.

To achieve improved transmission and ver Processing the supplementary data with full compatibility lity to existing, working according to "Level 1" Teletext receivers are out of it DE 39 14 697 A1 known, the Er side Supplementary data for one teletext page in the form one or more assigned supplement pages transmitted and on the receiving end that of a desired one Teletext page associated supplementary page (s) of store the relevant teletext page (s).

The object of the invention is one Methods of the type mentioned the number of Minimize supplement pages.

This object is achieved by the kenn Drawing features of claim 1 solved.

Advantageous refinements and developments of The inventive method result from the Subclaims.  

The invention is based on one in the drawings illustrated embodiment explained in more detail. It shows:

Figure 1 is a schematic representation of the known Teletext WST standard.

Fig. 2 is a schematic representation of the method according to the earlier patent application P 39 14 697.9;

Fig. 3 is a schematic representation of the inventive method and

Fig. 4 is a block diagram of an embodiment of a circuit arrangement for performing the method according to the invention.

In contrast to the Teletext WST standard ( Fig. 1) who in addition to conventional Teletext pages ("Grundsei th") transmit so-called supplementary pages, which are preferably structured in the format of the Teletext pages. As shown in Fig. 2 and 3 show, the assigned to a particular teletext page (s) complementary page (s) contain a higher WST-level (z. B. Level 2/3) missing data ( "supplemental data"). In Fig. 3, the "Le vel 1" page 100 with the subcode 0000 and the supplementary pages 10A 0001 and 10A 0002 is given as an example. The first hexa decimal numbered supplementary page 10A 0001 contains a specially marked section which contains supplementary data that are not only for the associated "Level 1" page 100 0000, but also for other "Level 1" pages - for example for the Page 104 0001 - are valid. In this example, the supplementary data for 104 0001 consists of the specially marked section from page 10A 0001, which is not sent separately (again), and the associated supplementary page 10E 0100.

Table 1 below shows which hexadecimal Supplementary page numbers between the individual basic pages 100 and 199 are assigned, for example.

The same applies to basic pages with page numbers from 200 upwards des. For example, the base 104 are the additions tongue side 10E, the base side 109 the supplementary side 1E0 and basic page 199 the supplementary page 1E9 orderly.

An essential feature of the invention is that Supplementary data for subordinate pages under pages numbers from higher-level page numbers are transmitted. At a well-known teletext transmission method ("TOP" - System) is shown in a separate teletext page ("Ba sic-TOP-Table ") information about each basic page in the cycle and their assignment to other pages in the form a classification in page, group, block transfer This classification is used here to parent and child pages from each other to below divorce. There is an exact defi for each basic page nated place (according to columns and rows) on the separate right side (BT table) is provided.

As another separate page ("pseudo table" or "PT") is after the same column and row assignment transfer as in the BT table and PT table, the coding of which is shown in Table II. The PT The table contains for each basic page (in place of it a specific PT code is located) information about the number the supplementary pages and additional information about whether additional supplementary data in parent Pages exist.  

Table II

Table III below shows the calculation rule with which with multiple pages (= base page plus sub page (s) from the subcode of the basic page and the number of the supplementary pages (Table II) on the subcode of the Supplementary pages can be closed. Example Weise have two supplementary pages to the base page 0001 the subcode 0101 and 0102. The subcode of the basic page represents an "extended page number", so have e.g. B. the sub-pages of the multiple page No. 120 die Page numbers 120 0001, 120 0002. . . The number names Components 0001, 0002 represent the subcodes.

Table III

In Table IV below is an example play a cycle according to the inventive method ("Higher level cycle").

Table IV

In the cycle shown there are several pages to one Group and several groups combined into one block sums up. A code 1 from Table II signals at for example on page 110 that only a supplement page from page 110 and no further additions pages from the parent page 100 are available. On the other hand, page 111 with PT code 8 signals that there are no separate supplementary pages, but specially marked sections in the Er on the supplementary page from page 110 have to.  

On the receiver side ( FIG. 4), basic data and supplementary data are equally separated from the video signal in a separation stage 10 and compiled into individual teletext pages. Each teletext page is fed via the output line 11 to a gate circuit 30 , which supplies the supplied teletext page via a read line 31 to a page buffer 40 if a control circuit 50 to be explained in more detail on an output line 51 supplies the gate circuit 30 with a release signal. Furthermore, the control circuit 50 effects an addressing of the page buffer 40 for the reading process via a further output line 52 . The reading process of the page buffer 40 is also carried out under the control of the control circuit 50 via a third output line 53 .

The control circuit 50 are supplied via a line 21 from a page number extraction circuit 20, the page numbers of the teletext pages occurring on the line. For this purpose, the decoupling circuit 20 detects the number of each teletext page fed from line 11 via a branch line 12 . The control circuit 50 is also connected to the input 70 operated by the user. The desired page number is supplied to the control circuit 50 via a line 71 . Meets a separate page with the page numbers of the basic pages (so-called "Basic-TOP-Table") or another special page (PT table according to Table II) with the information whether specially marked sections with supplementary data for subordinate pages are included, and of the number of supplementary pages for each assigned basic page, which occur in the cycle of the teletext pages or in a section of the cycle, these special pages are automatically fed to the intermediate page memory 40 . The data of this cached exception pages via the read data line 54 to the control circuit 50 is transmitted which, which is connected via a bidirectional bus 61 to the control circuit 50 determines the page numbers and the corresponding number of supplementary pages for each page number and store in a page numbers 60 stores .

It is assumed that the user e.g. B. has selected page # 111 by pressing the keyboard 70 . The control circuit 50 determines the number and the page numbers of the associated supplementary pages for this selected page. If, for example, the basic page # 111 is supplemented by supplementary data from the higher-level page 110 (Table II), the supplementary page has the page number # 11A. As soon as one of these pages occurs in the cycle, which is communicated to the control circuit 50 by the decoupling circuit 20 , an enable signal for the gate circuit 30 appears on the output line 51 , whereupon the basic page # 111, for example via the line 31, into the memory location # 1, the supplementary page 11A is stored in the storage space # 2 of the page buffer 40 . As already mentioned, the addressing to the memory locations takes place under the control of the control circuit 50 via the output line 52 . After the two pages viewed have been read in, the control circuit 50 generates a read command for the storage location # 1 via the output line 53 , whereupon the base page # 111 is read out from the page buffer 40 to a decoder for basic data 80 via the line 41 . The basic data decoder 80 appropriately decodes page # 111 and passes the resulting data over line 91 to a processor 90 . In addition, the control circuit 50 issues a read command for memory location # 2 via the output line 53 and the supplementary page 11A is read out via line 42 to a decoder for supplementary data 81 . The decoder for supplementary data 81 decodes the data in the specially marked section of the supplementary page in a suitable manner and transfers the resulting data via line 92 to the processor 90 , which processes the decoded data of all three sides together as a video signal with the components R, G, B and S for example on the screen of a television receiver.

In a special embodiment, the decoder for basic data 80 consists of a teletext level 1 decoder and the decoder for the supplementary data transmitted in a screen text structure consists of a screen text (BTX) decoder.

The control circuit 50 can also perform an automatic allocation of the remaining two memory locations # 3 and # 4 of the page buffer 40 with further pages after the user requests for page # 111. The next following page number is found in page number memory 60, for example, page # 112. In addition, the control circuit 50 determines, for example (Tab. IV), that the basic page # 112 is supplemented by the supplementary page # 11C and the particularly marked section from the page 11A which has already been loaded on storage space # 2. Pages # 112 and 110 can consequently be buffered in the manner already described after their appearance in the teletext system in memory locations 3 and # 4 and displayed on demand together with the general data from memory # 2 on the screen.

With the aid of the method according to the invention, the available intermediate page memory 40 can be optimally used, since the supplementary data in the specially marked sections apply to several basic pages and do not have to be reloaded each time.

The advantage of the method according to the invention is in that the additional data necessary for level 3 capacity can be minimized. The supplementary dates can not only for one side, but also for over ordered pages (groups), a block or for the entire cycle can be defined. So z. B. a new one Color table for the entire cycle, sports logos for the Block sport and same headings for news groups can be agreed.

Claims (7)

1. Method for the transmission of periodically repetitive teletext data in a television signal, in which the receiving side separates the teletext data from the television signal, the data belonging to each teletext page (base page) is collected and the teletext pages compiled in this way are stored, with the transmitting side In addition to the teletext basic data of conventionally constructed teletext pages, supplementary data for one teletext page each in the form of one or more assigned supplementary pages with page numbers in the hexadecimal system are transmitted to those who are stored on the receiving side separately from the basic data of a desired teletext page and processed in such a way that at those character locations where there is no supplementary data, the characters assigned to the basic data are displayed, and that at those character locations where supplementary data are available which interact with the basic data it the characters associated with the supplementary data are displayed, characterized in that the supplementary data for one, more or all of the teletext pages are structured and transmitted in the format of conventional teletext pages in one or more supplementary pages, that the page numbers of the supplementary pages coded in the hexadecimal system are defined according to a Scheme are assigned to the page numbers of associated, conventional teletext pages (basic pages), which are arranged in the decimal system and can be selected using the numeric keypad, so that in a further, separate teletext page, information about each basic page in the cycle and its assignment to other basic pages in the form of an overlay or subordination is transmitted, and that supplementary data for subordinate teletext pages are transmitted under page numbers of superordinate teletext pages. 2. The method according to claim 1, characterized ge indicates that the supplementary data transmitted in the send code of the screen text standard the.   3. The method according to claim 2, characterized ge indicates that at the receiving end separated decodings for the basic data and the Supplementary data are provided. 4. The method according to any one of claims 1 to 3, because characterized in that a separate information is transmitted about whether and if necessary how many supplement pages with supplement data for several teletext pages and whether and if necessary. how many supplement pages only with page-specific ones Supplementary data for each teletext page to be supplemented in Teletext cycle are included. 5. The method according to any one of claims 1 to 4, because characterized in that the separate information in the format of a supplement page is transmitted. 6. The method according to any one of claims 1 to 5, because characterized in that the Er valid at least for several teletext pages supplementary data with a compared to the basic data increased error protection. 7. The method according to any one of claims 1 to 6, there characterized in that the Supplementary data at least partially error protection display data for the assigned basic data, which on the receiving side for correction and if necessary for Substitution of assigned, disturbed basic data ten can be used.