GB2107159A - Television broadcast receiving arrangement comprising a videotext (teletext) decoder - Google Patents

Abstract

For reception of Videotext (teletext) data transmitted together with video signals, a television broadcast receiving arrangement contains a Videotext decoder in which, between the data output of the scanner (11) scanning the Videotext data, and the input of the page buffer (13) in which the data of the Videotext page as selected via a page selection circuit (16), are stored there is connected additionally a further storage arrangement (12), solid state or e.g. a video recorder, sufficient for storing the data of at least those Videotext pages which are combined in one magazine. A selected Videotext page can then be directly fetched from this magazine store, loaded into page buffer (13) and converted by character generator (14) for display (8). The average waiting time, normally relatively long, before a selected Videotext page is displayed, is reduced to the relatively short time of access to a Videotext page in the magazine store. <IMAGE>

Description

SPECIFICATION Television broadcast receiving arrangement comprising a videotext (teletext) decoder The invention relates to a television broadcast receiving arrangement, particularly a Videotext (Teletext) decoder.

For quite some time some broadcasting networks transmit on the radiated radiofrequency carrier not only the usual television programs but, in the intervals of the signal flow required for television broadcasting, there are transmitted so-called Videotext or Teletext signals containing an information which is completely separated from that of the television program, and which can likewise be received by a receiver of the type suitable for receiving television programs. For this purpose, the receiver permitting the reception of television broadcast transmissions is provided with an additional Teletext decoder with the aid of which the Teletext data as contained in the video signal flow, can be read out, stored and converted to signals capable of being displayed on a TV screen.

One such decoder is known, for example, from the technical journal "radio mentor" 1976, pp 483-486. This decoder contains a data scanner by which the data are scanned out of the demodulated video signal of a television receiver, and read out in a form capable of being processed for the storing in the page buffer of a page-buffer arrangement of the decoder. The information is transmitted in a pagewise manner, with one page having a format capable of being displayed on the screen of a television receiver and includes, for example, twenty-four lines at roughly forty characters each. With the aid of a page selector of the decoder, the user can select the desired page which, following the selection, is stored in the page buffer into which the information is capable of being written and read out.Between the output of the page buffer and the video amplifier of the television picture tube, there is inserted a character and symbol generator by which the videotext data as stored in the page buffer, is converted to visually readable characters and symbols capable of being displayed on the TV screen.

The data are transmitted, for example, during the vertical blanking interval of the video signal flow of a television field. In one example given in the printed publication "Technische Informationen für die Industrie" No. 800407 of the firm of VALVO, it is suggested to transmit two lines of a Videotext page per field. On account of this, the waiting time for the appearance of a page selected from the larger number, for example, from several hundred Videotext pages, may last relatively long, so that the advantage of the additionally offered information is partly lost again.

It is an object of the invention to design a television receiver of the type mentioned hereinbefore, in such a way that the waiting time for the appearance of a selected Videotext page on the screen is considerably reduced.

According to the present invention there is provided a Videotext (Teletext) decoder in or for a television broadcast receiving arrangement comprising a receiving and demodulating circuit and video output for a demodulated video signal, the decoder including a data scanner for scanning Videotext data from the demodulated video signal and for the output of these data, a page-buffer arrangement including a write-in and read-out type of page buffer for storing the data for one Videotext page to be displayed on a screen, a page selection circuit for storing a preselected Videotext page into the page buffer, and a further storage arrangement between the data outputs of the data scanner and the inputs of the page-buffer arrangement, the further storage arrangement including a write-in and read-out type of storing device with the storage contents thereof at least including the extent for storing the data of the pages of a Videotext magazine, and a page selection circuit connected to an address selection input of a read-out control circuit of said magazine storage arrangement.

The invention offers the advantage that, directly after the switching to the operating state "Videotext Reception" of the television receiver, the scanned Videotext data are continuously stored into the so-called magazine store and that, at the latest after the completion of this storing operation, there is provided a direct access tothe Videotext pages as stored in the magazine store.

Accordingly, the waiting time for one selected Videotext page, only still consists of the time required for the access to this particular page in the magazine store.

Advantageous further embodiments of the invention are described such as advantageous measures relating to an embodiment, in which the magazine store is designed in such a way that it cannot be read out during the storing process.

In the following, the invention will now be explained in greater detail with reference to some examples of embodiment shown in figures 1 to 3 of the accompanying drawings, in which: Fig. 1 shows a block diagram of a television receiver which is provided with a Videotext decoder containing a magazine store, Fig. 2 shows a block diagram of a Videotext decoder whose magazine store is a storage medium in which information is capable of being stored and read out via recording and playback heads, and Fig. 3 shows a block diagram of a television receiving arrangement consisting of a television set and of a video recorder, and in which the television set as well as the video recorder each contain a Videotext decoder.

The exemplified embodiment of the invention as shown in Fig. 1 is a television receiver containing a receiving and demodulating circuit 1, a video signal processing circuit 2, a video amplifying and deflecting circuit 3 for a picture tube 4, as well as Videotext decoder 5. The television signal as received via the antenna 6 of the receiver, is demodulated in the circuit 1, 50 that the demodulated video signal is capable of being taken off the video output 7 thereof. This signal, in the video signal processing circuit 2, is converted in such a way that, following amplification in circuit 3, it displays the transmitted television picture on the screen 8 of the picture tube 4.

Moreover, the input 9 of the Videotext decoder is connected or capable of being connected via a switch 10, to the video output 7 of the receiving and demodulating circuit 1. The Videotext decoder 5 includes a data scanning circuit 11, a magazine storing arrangement 12 connected to the outputs thereof, a page-buffer arrangement 1 3 connected to the output thereof, a character and symbol generator 14 connected to the output of the page-buffer arrangement, with the output thereof forming the output 1 5 of the Videotext decoder 5, as well as a page selecting circuit 1 6 whose data outputs 1 7 are connected to the address selecting input 1 8 of the read-out control circuit as contained in the control circuit 19 of the magazine storing arrangement 12. The data scanning circuit 11, at the video output 7 of the receiving and demodulating circuit 1, scans the Videotext signals as appearing in the signal flow of the video signal, converts them into signals which are capable of being stored, and sorts them in accordance with page number data (magazine number and page number) M+S, line number data R for marking the lines within a Videotext page, and into the actual Videotext data T, and makes these signals available at the corresponding data outputs M+S, R, T.These data are stored in a magazine store (memory) 20 which is capable of being written in and read out.

The control circuit 1 9 of the magazine storing arrangement 20 organizes the periods for writing and reading into and out of the magazine store 20 as well as, during the read-in process, the storage location in the magazine store. On the page selecting circuit 16, the user sets the respective Videotext page which is required to be displayed on the screen 8 of the TV set.In this. way, via the read out control circuit of the control arrangement 19 of the magazine storing arrangement 12, those storage locations of the magazine store 20 are addressed whose contents are to be trvansfe'rred to the page buffer 21 of the pagebuffer arrangement 1 3. The writing into the page buffer is controlled via the control circuit 22 of the page-buffer arrangement 13 which, in turn, is controlled by the control circuit 1 9 of the magazine storing arrangement 20.During Videotext operation, the input of the picture amplifier and deflection circuit 3 is disconnected from the output of the video signal processing circuit 2 of the television receiver and, via a change-over switch 23, is connected to the output 1 5 of the Videotext decoder, so that the information as stored in the page buffer, following its conversion in the character and symbol generator 14, is displayed on the screen 8 of the picture tube 4 of the television receiver.

The block diagram of Fig. 2 shows a further example of embodiment of a Videotext decoder which, with its input 9 and with its output 15, in place of the Videotext coder 5, is capable of being connected to the television receiver shown in Fig.

1. The magazine store in the embodiment shown in Fig. 2, is a magnetic storage medium deposited on a recording tape 24. The tape 24 is schematically shown in Fig. 2, is a length of a magnetic tape, for example, which is supported in a magnetic tape drive 25 and into which, with the aid of a recording head 26, data can be written into the magnetic storage layer of the tape and, with the aid of a playback head 27, the data as stored in the magnetic tape, can be read out. Both the writing in and the reading out of the data, as well as the passage of the tape are controlled by a recording-playback control circuit 28 of the magnetic tape drive 25.

Between the data outputs of the data scanner 11 of the Videotext decoder and the data input 29, there is connected a coding circuit 30 which may also form part of the magnetic tape drive unit 25, and which converts the signal waveform of the output data, as produced by the data scanner, into a signal waveform suitable for storing on the magnetic tape 24. Likewise, to the data output 31 of the magnetic tape drive unit 25, there is connected a decoder 32 which may also form part of the magnetic drive unit 25 and which converts the signal waveform of the data as read out of the magnetic tape, into a signal waveform suitable for the further signal path.

The Videotext decoder is immediately ready to store when the television receiver is turned on. A write-control circuit 33 of the magazine storing arrangement which, in the given example of embodiment, may consist of the magnetic tape drive unit 25 with the inserted recording medium (tape), of the write-control circuit 33, a read control circuit and of an automatic station finding circuit 35, as well as of the coding circuit 30 and the decoder 32, controls the process of writing Videotext data as supplied by the data scanner 11, into the storage layer of the magnetic tape 24 in dependence upon the data M+S referring to the magazine and page numbers, and, for example, in dependence upon consecutive page designations.

The process of reading a selected Videotext page out of the magnetic tape, is triggered by the input of the desired Videotext page into the page selection circuit 1 6. This page selection circuit 1 6 puts the automatic station finding circuit 35 of the magazine storing arrangement into operation, so that the magnetic tape drive unit 25 is switched to the automatic station finding operation until the automatic station finder, via the playback head 27, recognizes the page number M+S on the magnetic tape 24 which corresponds to the number as set on the page selection circuit 1 6. Thereupon, the automatic station finding circuit 35 turns on the read-control circuit 34, so that the data as read out of the magnetic tape 24 and relating to the selected Videotext page, and via a gate circuit 36 which is controlled into the conducting state by the read control circuit, are stored into the page buffer 13.

Organizing this storage operation can be controlled, for example, likewise by the read control circuit 34 of the magazine storing arrangement, via a control lead 37. The signal path for the Videotext data, extending via the magazine store of the Videotext decoder as shown in Fig. 2, is indicated by the solid line 38 (Fig. 2).

Since during the process of writing into the magazine store of the magnetic tape 24 of the Videotext decoder as shown in Fig. 2, no searching operation can take place, the Videotext decoder contains a further signal path for the Videotext data R+T which is indicated by the solid line 39 in Fig. 2 and which, between the data output R+T for the Videotext data of the data scanner and the data input of the page buffer 13, contains a gate circuit 40.This gate circuit 40 is controlled by a comparator 41 whose one comparator input 42, via a gate circuit 43, is connected to the address data output M+S of the data scanner 11, and whose second comparator input 44 is connected to the data input 1 7 of the page selection circuit 1 6. During this writing-in process, the write-control circuit 39 of the magazine storage arrangement switches the gate circuit 41 preceding the one comparator input 42, via a control lead 45, to the conducting state and simultaneously, disables the station finding circuit 35.If the data of the address-data output M+S of the data scanner 11, as applied to the comparator input 42 of the comparator 41, are found to be in agreement with the page data of the page selection circuit 16 as applied to the other comparator input 44 of the comparator, the gate circuit 40 in the signal path 39 is switched via the comparator 41, to the conducting state. In this way, Videotext data relating to the selected Videotext-page, via the gatecircuit 40, are directly also applied to the input of the pagebuffer 1 3 into which they are stored, independently of storing these data into the magazine storage arrangement of the magnetic tape 24.

The television receiving arrangement shown as an example of embodiment of the invention in the block diagram of Fig. 3, consists of a television receiver 46 which, apart from the Videotext decoder 47 contained therein, corresponds to the television receiver as shown in Fig. 1, and of a video tape recorder 48 with a Videotext decoder 49 connected to this television receiver. In the -one switch position of the Videotext changeover switch 23, the television receiver 46.can be operated in the normal television picture transmission state and, in the other switch position of the change-over switch 23, it can be used for Videotext operation.In the operating state of the Videotext transmission, the comparator 41' switches the gate 40' to the conducting state whenever, at the address data output M+S of the data scanner 1 1 of the Videotext decoder 47 the page data correspond to the page number as set on the page selection circuit 1 6' of the Videotext decoder 47. The Videotext data R+T relating to the set Video-text page are then stored, via the gate circuit 14', into the page-buffer 13', and the associated characters and symbols of the stored Videotext page are displayed with the aid of the character and symbol generator 14' of the Videotext decoder 47, on the picture screen 8 of the television receiver 46.

The video tape recorder 48 likewise contains a receiving and demodulating circuit 50 to the video output 51 of which, via a changeover switch 52, there is connected the recordreproduce control circuit 28' of the video tape recorder's drive unit.

A television broadcast transmission received via the antenna 6' of the video tape recorder, is transferred via a record head 26' of the drive unit, to the video tape 24' and, by a playback head 27', can be scanned off the video tape and, via the record reproduce control circuit 28', and a changeover switch 53 coupled to the changeover switch 52, can be applied to the input of a playback circuit 54 of the video tape recorder 48.

From there the recorded television program is fed via a Videotext changeover switch 55 of the Video tape recorder 48 and a Video-Cassette Recorder changeover switch 56 of the television receiver 46, to the picture tube 4 thereof.

In the other switch position of the two changeover switches 52 and 53 which are coupled to one another, and which is indicated by the dashline in Fig. 3, the video tape drive unit of the video tape recorder 48 including the recordreproduce (playback) control circuit 28, the record head 26 and the playback head 27', as well as the video tape 24', together with the Videotext decoder 49 thereof, forms a Videotext decoder arrangement which corresponds to the text decoder arrangement as shown in Fig. 2, and which also acts in the same way as the Videotext decoder arrangement as shown in Fig. 2.

In the switch position of the two changeover switches 55 and 56 indicated by the dashline in Fig. 3, the Videotext data of the respective Videotext page as selected by means of a page selection circuit 16, are fed directly from the Videotext data output R+T of the data scanner 11 of the Videotext decoder 49, via the gate circuit 40, to the page buffer 21 of the page-buffer arrangement 13, and the associated characters and symbols are applied, via the generator 14, to the picture screen 8 of the television receiver 46.

Accordingly, for displaying the Videotext information on a television receiving arrangement of the type as shown in Fig. 3, it is also possible to use television receivers not containing a Videotext decoder 47.

The television broadcast receiving arrangement as shown in Fig. 3 in particular, offers the advantage that during normal television broadcast reception, the entire transmitted Videotext information can be stored in the magazine store, and that in the course of the later call-up of individual Videotext pages, these pages can be retrieved from the magazine store which has a substantially shorter average access time than the one required for the retrieval of directly transmitted Videotext pages.

Claims (9)

Claims

1. A videotext (teletext) decoder in or for a television broadcast receiving arrangement comprising a receiving and demodulating circuit and video output for a demodulated video signal, the decoder including a data scanner for scanning Videotext data from the demodulated video signal and for the output of these data, a page-buffer arrangement including a write-in and read-out type of page buffer for storing the data for one Videotext page to be displayed on a screen, a page selection circuit for storing a preselected Videotext page into the page buffer, and a further storage arrangement between the data outputs of the data scanner and the inputs of the page-buffer arrangement the further storage arrangement including a write-in and read-out type of storing device with the storage contents thereof at least including the extent for storing the data of the pages of a Videotext magazine, and a page selection circuit connected to an address selection input of a read-out control circuit of said magazine storage arrangement.

2. A decoder or television broadcast receiving arrangement as claimed in claim 1, wherein said magazine store is either a semiconductor memory or a magnetic bubble memory.

3. A decoder or television broadcast receiving arrangement as claimed in claim 1, wherein said magazine store is a tape or disk shaped recording medium comprising a write-in and read-out type of storage medium.

4. A decoder or television broadcast receiving arrangement as claimed in claim 3, wherein said storage medium of said recording medium is a magnetic type of storage medium.

5. A decoder or television broadcast receiving arrangement as claimed in claims 3 or 4, wherein said magazine store is either a video tape or a video disk or part of a video tape or video disk recorder and playback device, the input of the record-playback control circuit for the record head or the record-playback head of the recorder, via a changeover switch is connected to the data outputs (M, S, R, T) of said data scanner if necessary by interconnecting a coding circuit, and that the output of said record-playback control circuit of said playback head or said recordplayback head of the recorder, likewise via a changeover switch is connected to the data input of said page buffer, if necessary by interconnecting a decoding circuit.

6. A decoder or television broadcast receiving arrangement as claimed in claim 5, wherein said read-out control circuit of said storage arrangement containing said magazine store, contains a storage location search arrangement, to the address-selection input of which the data outputs of said page selection circuit are connected.

7. A decoder or television broadcast receiving arrangement as claimed in claims 5 or 6, wherein said data scanner is connected to a video output for the demodulated video signal of a receiving and demodulation circuit of said recording and playback device.

8. A decoder or television broadcast receiving arrangement as claimed in any one of the preceding claims, wherein a gate circuit is arranged paraliel in relation to the data input/output of said further storage arrangement containing said magazine store, with the control input thereof being connected to a comparator whose one comparator input is connected to the address data output of said data scanner, and whose other comparator input is connected to the data outputs of said page selection circuit.

9. A decoder or television broadcast receiving arrangement as claimed in claim 8, wherein said storage arrangement containing said magazine store comprises a signal output which is connected to an inhibiting input of said said comparator at which, during the state in which the storage arrangement containing said magazine store is capable of being read out, there appears a signal inhibiting said comparator.

1 0. A decoder or television broadcast receiving arrangement substantially as hereinbefore described with reference to Fig. 1, Fig. 2, Fig. 1 and Fig. 2, or Fig. 3 of the accompanying drawings.