U.S. Philips Corporation

U.S. Philips Electronics

Henricus A Van Gestel

Eddy A Odijk

Rogatus H Wester

Gerardus J Reintjes

Johannis M Jansen

There exists a problem of backwards compatibility and future proofness of data transmission systems and, more particularly, interactive television broadcast transmissions. In view hereof, service providers must take into account that their service is to be processed by receivers having different capabilities. To this end, operational signals for different receiver types are identified by respective level data (operation.sub.-- level) defining which receiver capabilities are required to perform the operation. Two operation levels (full.sub.-- operation.sub.-- level and minimum.sub.-- operation.sub.-- level) are sufficient. More levels can be defined by means of chaining techniques. In a practical embodiment, a plurality of operations is packed in a transmission block. Events (e.g., user actions) are represented by an index to the list, the index depending on whether the receiver has full or minimal capabilities.

Compatible transmission and reception of operational signals to be

An arrangement and method is disclosed for transmitting data items to a receiver for selective display on said receiver. The data items may collectively constitute an electronic television program guide or a database of products and services for electronic shopping purposes. By transmitting auxiliary presentation and navigation information, the information provider may determine how a receiver displays the data items and how the receiver needs to respond to user actions. Sometimes, however, it is desirable for a receiver to respond in a setmaker-defined manner, even if navigation and presentation data are provided by the setmaker. In order to solve possible conflicts between the information provider's interests and the setmaker industries' interests, the transmission includes a copyright bit which allows an information provider to indicate explicitly whether or not a receiver is allowed to ignore the transmitted presentation and/or navigation data.

Transmission of data items

A system for transmitting a plurality of data items from a transmitter to one or more receivers. Each data item (Di) is identified by a unique number (i) within a given range. According to the invention, a field (F) comprising both ends (k.sub.1,k.sub.2) of the given range is also transmitted. This allows a receiver to check whether all data items have been received and to check which data item(s) is (are) missing, if any. The invention may generally be used in systems delivering data items to multimedia stations. The invention is particularly suitable for transmitting electronic program guide information in a television broadcast system.

By encoding references to teletext pages as an offset to a referenced teletext page, significant gains in transmission efficiency can be realized. The current teletext standard provides a mechanism for linking teletext pages, but the maximum number of different links supported by the teletext standard is insufficient to cover the need for more links for novel media services such as the transmission of Electronic Program Guides (EPG). An efficient extension of the number of links which can be supported is provided by coding further links as an offset with respect to the existing links in a conventional teletext link packet.

Method and device for transmitting and receiving teletext data

Conventional teletext decoders only respond to teletext data lines in the vertical blanking interval of a television signal. The decoders erroneously respond to conventional full-channel teletext transmissions in which all lines of the television signal are used for teletext. The method in accordance with the invention transmits teletext pages in the vertical blanking interval of the television signal in a conventional manner. Additionally, pages are also transmitted in the active video interval. A supplemental page header in each active video interval is provided to prevent teletext rows in the vertical blanking interval from being interpreted as rows of a page which is transmitted in the active video interval.

Method and arrangement for transmitting teletext pages in the vertical

Teletext page signals are transmitted in a format providing basic pages and extension pages, and a table which includes a code for indexing extension pages to the basic pages with which they are to be used. The code includes a multibit value for selecting an extension page from a list, and a single bit for selecting or not selecting a predetermined common extension page. Each extension page includes signals for enhancing the basic page or pages to a higher level display.

Method of transmitting teltext pages including an index table with a

Method, transmitter and receiver for transmitting, receiving and displaying teletext pages. A Level 1 teletext page transmitted in a known manner is extended to a higher display level using extension signals. To activate a desired attribute in an area covering a plurality of rows, the extension signals include a height code which indicates the number of further rows in which the further attributes must be repeated.

Method of transmitting teletext pages

A table contains codes for consecutive decimally numbered pages and pages whose numbers contain hexadecimal digits. Codes for all the pages having decimal units numbers are arranged in rows and columns such that a column contains codes for pages having a same units number, and codes for pages having a same tens number (whether decimal or hexadecimal) are in the same row. Codes for pages having a hexadecimal units number are arranged in a continuation of the rows and columns, hexadecimal units being arranged in the columns under the corresponding decimal units.

Method of transmitting teletext page codes for hexadecimal pages

Teletext page signals are transmitted in a format providing only basic characters and colors, along with extension signals enlarging the character set, colors, and other presentation information which is used by decoders and display systems having more extensive capabilities. Decoders ignore extension signals intended for a higher level display than the associated apparatus. A code is added identifying the level of display for which extension signals are intended, so that extension signals can be transmitted for use only by a display of a given capability, without undesired use by a higher level display.

Method of transmitting teletext pages with format-related codes

A television receiver includes a teletext decoder which is adapted to check whether a keyword entered by the user occurs in a teletext cycle. The teletext pages with the searched keyword, or their page numbers, are identified and stored for later display or selection. The receiver has arrow keys for selecting the keyword on the display screen so that an alphabetical keyboard is not necessary. The receiver also includes a non-volatile memory in which a personal index of keywords can be programmed.

Teletext decoder and television receiver provided with a teletext decoder

Teletext decoder including an error detection and correction circuit in which the detection and correction of bit errors is effected in a serially manner in Hamming bytes. The teletext decoder includes selection means for selecting predetermined bits from the received bytes, modulo-2 accumulators for generating a syndrome word which indicates the presence and position of bit errors, decoding means for generating a correction value and correction means for correcting faulty data bits during the serial transfer. The error detection and correction circuit can also be used with other data communication systems as well as with digital storage means.

Teletext decoder with error detection and correction

In a teletext decoder circuit the character generator supplies picture elements at a rate of nominally approximately 6 MHz under the control of display pulses occurring at the same rate. These display pulses are derived from reference clock pulses which occur at a rate which is not a rational multiple of 6 MHz. The character generator comprises a generator circuit which receives the reference clock pulses and selects, from each series of N reference clock pulses, as many pulses as correspond to the number of horizontal picture elements constituting a character, while the time interval of N reference clock pulses corresponds to the desired width of the characters to be displayed. The character generator supplies picture elements of distinct length, while the length of a picture element is dependent on the ordinal number of this picture element in the character.

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Eindhoven, Netherlands

Henricus A Van Gestel