DE3937653A1 - Teletext data transmission system - Google Patents

Abstract

The teletext data transmission system allows the periodically repeated teletext data to be transmitted alongside the television signals, with intermediate storage of the extracted teletext data includes complementary data for each teletext page, which is transmitted as at least one complementary page, with separate storage of the latter from the associated teletext pages at the reception end. Pref. the complementary page has a standard page format and holds the page numbers in a hexadecimal system.

Description

The invention relates to a method according to the Preamble of claim 1. Such a procedure ren is from the earlier patent application P 39 14 697.9 known.

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 expansion levels "Level 2" and "Level 3", provides for the transmission of supplementary data in so-called pseudo-rows (also called "ghost rows"), which are not used by "Level 1" , but have 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 reference to FIG. 1 for row number # 26 (cf. also the literature reference "Broadcasting communications" mentioned at the beginning). Since the teletext receiver does not receive any information about the number of pseudo rows transmitted to a teletext page (basic data), the decoder does not "know" whether, which and possibly how many pseudo rows have been sent to a teletext page. A correct evaluation can therefore only take place if the desired teletext page and all assigned pseudo series have been received completely. Furthermore, in the decoder, an additional memory space, e.g. B. 4 kbytes, are constantly available, which is not otherwise usable in the absence of transmission of pseudo-series.

For improved transmission and processing Processing of supplementary data with full compatibility to existing teletext receivers working according to "Level 1" it is gladly from the earlier patent application P 39 14 697.9 Known, the supplementary data for each a teletext page in the form of one or more assigned To transmit supplementary pages and the receiving side a supplement associated with a desired teletext page page (s) separate from the relevant teletext page (s) caching.

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

According to the invention, this object is characterized by the solved the features of claim 1.

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 10 A 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 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.

Table I

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

An essential feature of the invention is that Supplementary data for subordinate pages under pages Numbers from higher-level page numbers are transferred to who the. In a known teletext transmission method ("TOP" system) is in a separate teletext page ("Basic-TOP-Table") information about every reason page in the cycle and their assignment to other pages in the form of a classification in page, group, block transfer. This classification is used here to separate parent and child pages from each other divorce. There is a de for each basic page Finished space (according to columns and rows) on the ge special page (BT table) is provided.

As another separate page ("pseudo table" or "PT") is after the same column and row assignment As in the BT table, the PT table, whose Coding is shown in Table II. The PT table contains for each Basic page (where a certain PT code is located information about the number of supplementary pages and additional information about whether more Supplementary data available in parent pages are.  

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, several pages are combined into one group and several groups into a block. A code 1 from Table II signals, for example, on page 110 that there is only one supplementary page from page 110 and no further supplementary pages from parent page 100. The page 111 with the PT code 8, on the other hand, signals that there are no separate supplementary pages, but specially marked sections in the supplementary page from page 110 must be taken into account.

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 via the line 41 from the page buffer 40 to a decoder for basic data 80 . 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. As the next page number, for example, page # 112 is found in page number memory 60 . 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 that the additional data capacity required for level 3 can be minimized. The supplementary data can be defined not only for one page, but also for higher-level pages (groups), a block or for the entire cycle. So z. B. a new color table for the entire cycle, sports logos for the sports block and the same headlines for news groups can be agreed.

Claims (10)

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 pertaining to each teletext page is collected and the teletext pages compiled in this way are buffered, the transmitting side being in addition to the teletext - Basic data of conventionally constructed teletext pages Supplementary data for one teletext page in each case are transmitted in the form of one or more associated supplementary pages, with the supplementary page (s) associated with a desired teletext page being temporarily stored on the receiving side, separate from the relevant teletext page (s) and wherein the temporarily stored basic data and supplementary data are processed in such a way that the characters assigned to the basic data are displayed at those character locations where there is no supplementary data, and that at those characters hen places where there are supplementary data that are displayed for the basic data in cooperation with the supplementary data associated characters, characterized in that the supplementary data for several or all teletext pages are transmitted in at least one supplementary page. 2. The method according to claim 1, characterized characterized that the supplement pages in the format of conventional teletext pages are structured. 3. The method according to claim 1 or 2, characterized characterized that the supplement pages with page numbers in hexadecimal system are seen. 4. The method according to claim 3, characterized characterized in that in hexadecimal system coded page numbers of the supplementary pages according to a fixed scheme in the decimal system arranged page numbers that can be selected using the numeric keypad the assigned conventional teletext pages are arranged. 5. The method according to any one of claims 1 to 4, characterized, that the supplementary data in the screen text construction code be transmitted.   6. The method according to claim 5, characterized characterized that receiving side separate decodings for the basic data and the Supplementary data are provided. 7. The method according to any one of claims 1 to 6, characterized in that separate information is transmitted, if and if so how many supplement pages with add data for several teletext pages as well as whether and if necessary, how many supplement pages only with page spec fish supplementary data for each teletext series to be supplemented te are included in the teletext cycle. 8. The method according to any one of claims 1 to 7, characterized in that the separate information in the format of a supplement page is transmitted. 9. The method according to any one of claims 1 to 8, characterized in that which apply at least to several teletext pages Supplementary data with one compared to the basic data increased error protection. 10. The method according to any one of claims 1 to 8, 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 be used.