DK172915B1 - Method for transmitting teletext signals, a number of teletext pages, apparatus for receiving teletext signals, and - Google Patents

Description

in DK 172915 B1

The invention relates to a method for transmitting teletext signals from a transmitter to a number of receivers, in which a number of consecutive and numbered teletext pages are continuously transmitted. In addition to the teletext pages designated for all receivers, a number of pages may be transmitted which are only intended to be received by one or more selected recipients. Each of these receivers is assigned a digital address and includes a repository for storing teletext pages. The invention further relates to a number of such consecutive and numbered teletext pages as well as an apparatus for receiving such teletext signals. Finally, the invention relates to the use of teletext signals to transmit pages which are only intended to be received by one or more selected recipients.

It is generally known to broadcast (broadcast) text over existing TV broadcasters in the form of so-called teletext, which in the following card is referred to as TTV. There is an international protocol for transmitting TTV signals.

Text pages can be sent, each containing up to 32 rows of text with 40 characters each. The text lines are commonly referred to as "rows" in the following, and hence in the following, to separate them from the 25 lines of the normal TV picture. Of the 32 rows of text, only the 24 are intended to be displayed on the TV receiver's screen. A number (usually 2) of rows are modulated in binary coded form onto each of the lines of the TV picture, which is in the so-called bi-led blanking interval. This range generally comprises the top 25 lines of the TV picture.

This TV signal, which, in addition to ordinary picture information, also contains TTV information, is broadcast from a TV transmitter and can then be received by TV receivers. However, the TTV information is only available to those TV receivers which contain a TTV decoder that can capture and store information for each line of TTV information. Such a decoder is usually arranged to store and maintain one page of TTV information at a time. This page can then be displayed on the TV receiver's screen, either on the same-5 colored background or with the normal TV picture as the background.

The TTV information is usually transmitted continuously as an ever-repeated sequence, also referred to as a TTV-10 loop. The loop may comprise a maximum of B so-called magazines, each comprising 100 pages. At the front of each row there are special characters that include. controls color, background color and the like. At the end of each row, there are corresponding checksums characters that can correct single-15 bit errors.

For each page there are a number of sub-pages (referred to in English as sub-pages) which are published successively. That is, at the first loop of the loop, the first 20 underside is emitted, at the next loop of the loop the next underside, and so forth. Thus, if there are n subpages, then n through the TTV loop is required before all n subpages are broadcast.

The TTV information in the loop is normally transmitted in sequence, so that a maximum of 8 magazines of 100 pages of 32 rows are continuously fed through the TTV loop. However, since each row is uniquely identified with magazine number and page number, the rows can be sent in any order, 30 if desired. It is not necessary to send empty magazines, pages or rows. It should be noted that for each pass it is possible to exchange the information on a given page.

35 With this system it is thus possible to give viewers of a TV station access to up to 800 pages of information of general interest. All viewers who have a TTV decoder have access to the same information.

US Patent No. 4,866,770 discloses a system by which it is possible to transfer information from e.g. a corporate headquarters to its departments or employees. There may be various types of information, including TTV information. The system allows certain information to be sent to all 10 recipients, while other information is only sent to individually addressable recipients. Furthermore, the information can be encrypted so that only the receivers provided with a decryption device are able to see the information. It is also disclosed that receivers may be provided with a storage device, e.g. in the form of a video recorder which can be controlled remotely by means of a control signal from the transmitter. Thus, a video recording, e.g. is sent at night and automatically stored on the VCR so that it can be played for the following 20 days.

However, this is a system specifically used for this purpose. For example, This is a non-public satellite company that offers companies-25 private communications between different departments using the company's satellite connection. This means that a system of broadcasting stations, satellites must be built for this purpose. The costs of this system must of course be borne by the users, which is why the system is primarily interested in users with a great need for information exchange between different departments. .

Furthermore, this system uses direct transmission on individually addressed TTV pages, which means that a given page e.g. is assigned to a specific recipient who seizes this page all the time. This is extremely limiting to the capacity of the system.

The invention provides a system which can function as a superstructure for an already existing TTV system. The system thus allows the transmission of TTV information to selected users without having to make major investments in broadcast equipment, etc. On the sending side, only equipment that can edit the desired messages as well as any coding equipment should be added. On the receiving side, just a recipient box must be obtained from the users who should be able to receive the special information.

Thus, for very small investments, it becomes possible to send information to selected recipients in the area covered by the TV station in question.

Furthermore, a much more flexible utilization of available capacity is achieved in the TTV system, with information for a particular recipient only seizing a TTV page shortly, after which it is available to other recipients.

This is achieved according to the invention by a method of the kind mentioned in the introduction, where on a given teletext page control signals are sent to the selected recipient (s), said control signals comprising addresses of the selected recipient (s) and information about at what time or times when teletext pages intended for said recipients will be sent. Thereafter, the specified pages are sent to said recipients and these pages are received by said recipients and stored in each recipient's storage.

This makes it possible to transfer a teletext page to one or more specific receivers by simply sending it in a single passage of the teletext loop, having been notified in advance of the decoder concerned that 5 DK 172915 B1 capture that page and store it in its storage. Then the page is in the receiver's store and can be freely read from there and displayed on the TV screen as needed. So the page in question should not be broadcast continuously from the 5 broadcasting station.

Thus, when there is a need to send an information page to a receiver, the system can simply select a randomly available TTV page, state this on the index page and send the information. The TTV site in question is thus immediately available to other information and / or other recipients.

By further sending as specified in claim 2 the particular 15 pages of similar character and background color, e.g. black text on black background, unauthorized viewers are prevented from seeing that teletext page, even though they should be able to capture it at one pass through the loop. In the recipients where the message is to be received, 20 simply needs to change the color of the characters and / or background, making the text visible.

To further enhance the security of unauthorized access to the messages intended only to be received by particular recipients, the messages as specified in claim 3 can be encrypted so that the text becomes visible only if the decoder is provided with a corresponding decryption device.

Further, as stated in claim 4, to provide a receiver with a modem and a telephone connection, it is possible that the recipient can, by means of this, request that certain information be sent to that particular recipient.

35 From the transmitter's side, on the first occasion given by means of control signals, a message will be sent to the recipient concerned that the page in question will now be sent so that it can be received and stored in the receiver.

By providing, as stated in claim 5, receivers with magnetic card readers, it is possible that the transmitter can demand that a particular magnetic card be loaded before a given information is sent to that recipient. This can be eg is used if you have to pay for 10 receipt of certain information or if only users who have a specific authorization code can receive the relevant pages.

As stated in claim 6, using the received and stored teletext pages received in a receiver for transmission over another TV transmitter or possibly a closed network, it becomes possible that a company e.g. can receive certain pages as described above and then forward them as normal teletext to a number of recipients located around 20 around the company. Thus, it is possible to send a particular page from the first transmitter to the first receiver, after which it transmits, via the second transmitter, that particular page to a certain recipient who can receive the signals from it.

25

The invention also relates, as discussed, to a number of consecutive and numbered teletext pages in a sequence or teletext loop. As stated in claim 7, including at least one of the pages comprises control signals for the selected recipient (s), the advantages described above are obtained.

In cases where there is a need to transfer a large number of teletext pages to a particular receiver, it is possible to allow those pages to seize an entire gene 35 through the sequence or teletext loop as described in Claim 8. This allows a large amount of information to be transferred to a particular recipient more quickly, while increasing the waiting time on a certain teletext page for the normal users.

In a particular embodiment described in claim 9, the teletext loop can be completely stopped, a particular page number being then transmitted a large number of times in succession to the same receiver. At each transmission of the page in question, this contains new information and each of the 10 pages thus transported is stored in that recipient.

An apparatus for receiving the above-described signals is disclosed in claim 10. The apparatus may furthermore, as specified in claim 11, be adapted to change the color of the characters and / or background of the received sides, and it may, as indicated in FIG. Claim 12 must be arranged to be able to decrypt information, which is encrypted before sending from the transmitter.

20

Further, as described in claims 13 and 14, the apparatus may comprise a modem which can be connected to a telephone connection as well as a magnetic card reader. As described in claim 15, the apparatus may be arranged so that the stored teletext information can be read out as a regular TV signal.

This makes it possible to see the desired information without the normal TV set provided with a normal teletext decoder.

Finally, the invention relates to the use of the above-described teletext signals to transmit, in addition to the teletext pages destined for all recipients, only intended to be received by one or more selected recipients. This use is described in claim 16.

35 8 DK 172915 B1

The invention is further explained below, by way of example only, by way of example, with reference to the accompanying drawings, in which: 1 shows a system for broadcasting teletext, with a TV transmitter and one of many TV receivers, as well as a receiver box according to the invention, with a connected TV receiver; FIG. 2 shows a receiver box according to the invention; FIG. 3 shows a data store at the TV transmitter with entries of 1 TTV page, a Teletext loop comprising the pages sequentially and continuously broadcast over the TV transmitter, and a data store in the receiver box, with entries of 1 TTV-15 and FIG. 4 shows a system with multiple TV transmitters.

In FIG. 1 is shown a commonly known system for broadcasting (broadcasting) of teletext (TTV). A repository 1 contains TTV information where TTV pages are stored as records in a register. The pages each contain up to 32 lines of text with 40 characters each. Said lines are commonly referred to hereinafter as "rows" to separate them from the lines of the TV picture. A TV generator 2 retrieves for each TV picture a number (usually 2) of rows in the storage and modulates each row - in binary form - into one of the lines of the TV picture which is in the so-called picture blanking interval . This range essentially comprises the top 25 lines of the TV picture.

These lines are outside the active part of the picture tube screen when the TV receiver is set properly.

The TV signal, which now contains, in addition to video information (the picture) 35, the TTV information, is transmitted by the transmitter 3 and 9 DK 172915 B1 is received by the TV receiver 4. This may contain a TTV decoder 5, which for each line with TTV information captures and stores that particular line of text. The decoder 5 is generally arranged to store and maintain one page 5 TTV information at a time. This page can be viewed on the TV receiver 4 screen, either on plain (black) background or with the regular TV picture as the background.

In addition, FIG. 1 shows a TV receiver 7 connected 10 to a receiver box 6 according to the invention. The TV antenna 10 is connected to the receiver box 6, which transmits the antenna signal to the antenna input 9 of the TV receiver 7. In addition, the receiver box is connected to a telephone line 8 via a built-in modem, whereby it can transmit and receive data 15 over the telephone line in a otherwise known manner.

In FIG. 2, the structure of a receiver box according to the invention is shown. The receiver box has an antenna input 20 whereby it is connected to a TV antenna or cable installation or the like, and through which it receives TV signals with TTV. At an output 21, the receiver box can deliver TV signals with TTV. The signal from the antenna input 20 goes to a TV tuner 22. From here, the demodulated video signal 23 goes to a TTV decoder 24. The signal 23 is also fed to a modulator 25 from which it - modulated on a carrier - can be transmitted on output 21. The TTV decoder 24 intercepts and stores one page of TTV information at a time.

The tuner 22, the TTV decoder 24 and the modulator 25 are components known per se from TV receivers or 30 video tape recorders.

In addition, via a so-called pass-through connection 37, the antenna signal 38 is passed directly from the antenna input 20 to the output 21 without being demodulated. This allows the connected TV receiver to receive all TV programs as usual, without the tuner 22 having to be tuned to that channel.

A microcomputer 26, comprising at least CPU 5 (calculator) 27, program storage 28, keyboard and / or remote controller 29 and data storage 30, controls the operation of the receiver box and handles TTV data received through the TTV decoder 24. The CPU can control via the command link 31 the TTV decoder 24 and the modulator 25, as well as the other units of the receiver box, an example of which is shown here, for example, a modem 33, a printer 35 and a card reader 36. Through the modem 33 and a telephone line 34, the CPU can communicating with remote devices, e.g. the device that delivers and stores the TTV information that the receiver box receives and stores.

15 For example, if the receiver box. if it detects an error in the received text, it can request retransmission when calling the sender. Modem 33 can also be used for calls to databases or other data providers, requesting the delivery of data such as TTV via a TV transmitter. With the printer 35, information or documentation can be provided to the user of the receiver box. Through the card reader, the receiver box can "receive electronic payment" for services provided through TTV or through a video decoder not shown in the receiver box, or the user's credentials for access to receive given information.

TTV data and text data can be transmitted between the receiver box units through the data connection 32, controlled by the microcomputer 26. For direct transmission of TTV data from the TTV decoder 24 to the modulator 25 (i.e. for direct viewing of the TTV), a data connection 39 is provided. , where TTV data is transmitted as a so-called RGB signal, ie. a kind of video signal.

For communication with external devices, e.g. for transmitting stored data otherwise than as a video signal or TV picture, there is a so-called data port 40. This port can e.g. is used when transmitting the stored data for retransmission as TTV over another TV transmitter.

In FIG. 3 shows the contents of a TTV loop. The term "loop" refers to the phenomenon that the TTV information is generally broadcast over the TV transmitter sequentially and continuously, and therefore temporarily constitutes a loop that is repeated indefinitely - with or without changes in content - as long as TTV is active. As previously mentioned 10 in the explanation of FIG. 1, the broadcast occurs with a number of rows (usually 2) in each TV picture.

The rows can be sent out at random, as they each carry a complete address with magazine and page numbers, but the usual is that the rows are sent in 15 order and page by page, magazine by magazine, from page 100 to page 899. Each broadcasting these pages is referred to as "a walkthrough of the TTV loop".

The TTV information 50 to be broadcast is stored in a register 20, where the individual entries are shown here as whole TTV pages. 52 represents the symbolic representation of the entire TTV loop, which contains pages 100 to 899, divided into 8 magazines of 100 pages.

As an example, it is shown that pages 540 and 541 each comprise 3 sub-pages. They are therefore shown in register 51 as triple entries. At the broadcast, in the first pass through the loop 52, subpages 540/1 and 541/1 are sent, at the second pass through subpages 540/2 and 541/2 and so on 30 still. When all of its subpages have been broadcast for a given page, start over with this page's subpage 1.

In the receiver box, there is a register 56 capable of accommodating TTV rows in the data store. However, the register's entries are shown here 35 as pages 57. As further explained elsewhere in this description, the receiver box can receive instructions contained in the transmitted TTV information.

As an example, it is shown that page 430 (53) contains instructions for the receiver box. The receiver box according to the invention may be programmed to receive, for example, page 430 at all times, and to respond to the instructions contained herein, which also includes instructions to which individual receiver boxes the instructions are valid. In this example, the instruction is intended to consist of the receiver box considered here to store for later viewing on the connected TV set, pages 540/1 to 541/3, a total of 6 pages, cf. 57. The receiver box will now in this and the the following 2 passes through the loop 52 capture and store the pages 540 and 541 and store them in the register 56.

The instructions on that page (here 430) can be many. As another example, the page may contain encryption keys which enable the receiver box to decrypt the received text before or after it is stored. As a third example, the page in question may contain instructions on how to edit the received TTV information before sending it to the connected TV-25 receiver. For example, be pages splitting, choice of colors for characters and background, etc.

As an example of application of the invention may be mentioned sending messages to a company's staff, at their private addresses. Such broadcasts could replace or supplement a staff sheet, technical or administrative instructions, or the like. As the messages are received by the recipients very quickly, urgent messages or messages that must necessarily be current can also be sent in this way.

13 DK 172915 B1

A TV station broadcasting TTV can distribute the said messages in its coverage area, provided that the company staff has TV, and sufficient reception conditions. In addition to the TTV installations already present on the TV station, 5 only equipment and programs are required to manage and possibly encrypt the information to be broadcast and place it appropriately in the storage of the TV station's TTV generator, cf. FIG. 1, pos. 1. Of course, a receiver box is required for each of the 10 TV receivers of the person, cf. 1, pos. 6th

Thus, small construction costs are required. There is virtually no transmission cost required, as spare capacity is utilized in the TV station's TTV system and since the TV transmitter is already in operation most of the time. The other operating expenses are mainly for the administration of the system and for editing the messages; this work would also have to be done if the messages were to be transmitted through other media. The application of the invention described herein therefore has considerable economic benefits.

Another example of an application of the invention may be broadcast of TTV over a system of television broadcasters transmitting a common program (eg nationwide) from a central source alternating with individual programs (eg regional programs). Both common (national) TV pages and individual (regional) TV pages are simultaneously broadcast over each broadcaster. All TTV pages are wanted to be managed and broadcast from a central source, which may or may not be the same central source generating the common TV program.

However, the common program is interrupted on each TV transmitter when it has to broadcast an individual program, and there is then no transmission connection for the TTV pages from the central source, as these are only available on the single TV transmitter which part of the video signal in the common program.

Using the invention, both the common and all individual TTV information can be distributed from the central source, installing on each of the system's TV transmitters a special version of the receiver box according to the invention, which, using the method according to the invention, causes storing both the common TTV-10 information and partly the individual TTV information to be broadcast over the TV channel in question.

The contents of TTV pages in the receiver box storage are transmitted via a data interface 40, cf. 2, for storage in a TTV generator, cf. 1, pos. 1. From the repository, both the common and individual TV pages can then be broadcast together with the individual TV program.

As a third example of an application of the invention 20 may be mentioned the transmission of large amounts of data from a database to a user of the database. An order can be made by the user to the database's voice response system from the user's telephone apparatus with keypad and 2-tone signaling, or from the receiver box keypad 29 via modem 25 33 and telephone line 34. When the order is placed, the telephone connection can be disconnected, and the database can then send via the data line the desired information to the apparatus which supplies the storage 1 on the TV station with data. Then, as described elsewhere in this application, the information can then be sent to the user's receiver box, where it is stored for later viewing on the user's TV receiver.

With this application of the invention, it is achieved that the user can access information from databases without any investment in apparatus other than the receiver box, which is priced far below, e.g. a PC installation. In addition 15 DK 172915 B1 saves telephone time as the user's telephone line is only recorded during the placing of the order.

In FIG. 4 shows one TV transmitter 60, by a system of TV-5 transmitters transmitting a common program (e.g. nationwide) from a central source 61, 62, alternating with individual programs (e.g. regional programs), from a local wedge 63. At each transmitter, both 10 common (nationwide) TV pages and individual (regional) TV pages are wanted simultaneously. All TTV pages are wanted to be managed and broadcast from a central source 64, which may be located at the same location as the central source 61 producing the common TV program.

15

A TTV generator 65 receives the TTV information from memory 64 on its data input 66 and video signal from source 61 on its video input 67. As discussed above, the TTV generator 65 modulates the TTV information onto certain of the video signal lines and transmits it modulated signal to the TV transmitter 62. Via a special connection 68 (for example a radio chain connection), the common TV program with TTV is transmitted to a regional TV station, with inter alia. the receiver 69 and the transmitter 60. Prior to the receiver 69, the received signal is applied to a receiver box 70 according to the invention; this receiver box can, as previously described, be programmed to receive the TTV signal and deliver it to its data port 71, cf. 2, pos. 40. By means of suitable apparatus, here symbolized by the double switch 72, the regional station's TV transmitter can be supplied either (in position I of switch 72) with the common TV signal received by the transmitter 62 with TTV, or (in the switch of 72 position II), with a signal from the TTV generator 73, which is composed of the regional video signal from the source 63 received by the TTV generator 73 at its video input 74, and the common TTV signal, which TTV generator 73 receives on its data input 75.

In this way, the 5 disadvantages mentioned elsewhere in this application are remedied that the common program on each regional TV transmitter is interrupted when it has to broadcast an individual program, and then there is no transmission connection for the TTV pages from the central source, as these are only available. on the individual TV transmitter as part of the video signal in the 10 common program.

Claims (16)

17 DK 172915 B1 A method for transmitting teletext signals from a transmitter (3) to a plurality of receivers (5, 7), in which a number of consecutive and numbered teletext pages are continuously transmitted and in addition to the teletext pages specific to all recipients may be transmitted a number of pages 10 intended only to be received by one or more selected recipients (7), each of which being assigned a digital address and comprising a digital address. storage for storing teletext pages, characterized in that, on a given teletext page, control signals are sent to the selected recipient (s) (7), said control signals comprising addresses of the selected recipient (s) and information on the time or times when teletext pages intended for said recipients will be sent; then sending the designated pages to 20 recipients is then sent, and said pages are received by said recipients (7) and stored in each recipient's storage. A method according to claim 1, wherein the teletext signals 25 contain information on which color respectively a given teletext page's characters and its background are to be displayed on said receivers (7), characterized in that the teletextes pages intended only to be received by one or more selected recipients are sent 30 with information that the pages' characters and background should be displayed in the same color and that said control signals include message to the selected recipients to change color characters and / or background, and then, upon displaying the said pages, the recipient then changes the color accordingly to make the characters visible. 18 DK 172915 B1 Method according to claim 1 or 2, characterized in that the information on the teletext pages which is only intended to be received by one or more selected recipients (7) is otherwise encrypted before it is encrypted. sent; that said control signals to the selected recipients include information on how the information can be recovered and that the information upon receipt in the selected recipients is restored by decryption. 10 Method according to claims 1-3, characterized in that a request is sent from a receiver (33) and a telephone connection (34) to the transmitter (3) to transmit one or more given teletext pages, and that these are then sent to that recipient (7). Method according to claim 4, wherein at least some of the selected receivers are provided with a magnetic card reader (36), characterized in that the transmitter (3), before a given teletext page is transmitted, by means of a said control signals request proof of the recipient's right to receive that information; the receiver thereof, after a correct magnetic card is loaded into the magnetic card reader (36), via said modem (33) and telephone connection (34) sends said evidence to the transmitter, and that the transmitter then sends the teletext page to the person concerned. recipient. Method according to claims 1-5, characterized in that the teletext pages stored in the storage of one or more receivers are transmitted as teletext signals over an additional TV transmitter (60) or a closed networks connected to that recipient. 35 19 DK 172915 B1 7. A number of consecutive and numbered teletext pages for transmission from a transmitter (3) to a number of receivers (5, 7) where, in addition to the teletext pages defined for all recipients, pages can be transmitted, which are only intended to be received by one or more selected recipients (7), each of these recipients being assigned a digital address, characterized in that at least one of the pages comprises control signals to the selected recipient (s) (7) ), and that at least one subsequent 10 page is intended to be received only by said one or more selected recipients (7), wherein said control signals include addresses of the recipient or recipients and information on which page number or page numbers will be sent. teletext pages intended for 15 said recipients (7). Teletext pages according to claim 7, characterized in that all said pages are intended to be received only by one or more selected recipients (7). Teletext pages according to claim 8, characterized in that all said pages have the same page number, that a page with this page number is transmitted a number of consecutive times and that it contains new information for each transmission 25, so that a large number of pages can be quickly sent to one or more selected recipients (7). An apparatus for receiving teletext signals from a transmitter (3) from which sequences of consecutive and numbered teletext pages are transmitted, which apparatus is assigned a digital address and is adapted to store a the number of pages received, characterized in that the apparatus is arranged to receive only control signals comprising the address of the apparatus and to be able to receive, depending on these control signals, a number of teletext pages which are intended to be received by this apparatus. Apparatus according to claim 10, wherein the teletext signals contain information about the color with which the characters of a given teletext page and the background respectively are to be displayed, characterized in that it is arranged in dependence on the received. control signals to be able to change the color of either characters or background of the pages 10 intended to be received by this apparatus. Apparatus according to claim 10 or 11, wherein the information on the pages intended to be received by selected receivers (7) is encrypted, characterized in that it comprises means to recover dependent control signals in response to received control signals. it sent information on decryption. Apparatus according to claims 10-12, characterized in that it further comprises a modem (33) adapted to transmit a request via a telephone connection (34) to the transmitter (5) to transmit one or more given teletext -pages. 25 Apparatus according to claim 13, characterized in that it further comprises a magnetic card reader (36) and it is arranged to be able to send a signal to the transmitter (5) via said correct card in the magnetic card reader (36). modem (33) and telephone connection (34). Apparatus according to claims 10-14, characterized in that it is arranged to be able to read any 35 of the stored teletext pages and that the read-out can be at least in the form of a normal TV signal. 21 DK 172915 B1 16. Use of teletext signals transmitted from a transmitter (5) to a number of receivers (5, 7) where a number of consecutive and numbered teletext pages are continuously transmitted and where certain receivers are assigned to every 5 a digital address and includes a repository for storing teletext pages, to transmit, in addition to the teletext pages destined for all recipients, only intended to be received by one or more selected recipients (7) sending control signals on a given teletext page to the selected recipient (s), where named control signals include addresses of the recipient or recipients and information on what time or times will subsequently be transmitted teletext pages intended for said recipients, after which the 15 pages designated for said recipients are transferred from the transmitter (3) to said recipients (7) and stored in each recipient's storage.