U.S. Philips Corporation

Wilhelmus J Christis

Peter J Janssen

Herman J Schmitz

Wilhelmus F Fekkes

Michael P Geerings

Hendrik Kolk

In a television transmission system, for example, a community antenna television system the transmitter station transmits a teletext page in an information channel, which page indicates in which TV channels this transmitter station transmits programmes. A receiver associated with this system is directly tuned, after switching on, to this information channel or starts a searching action for this channel. Once tuned to this information channel the relevant teletext page is captured and the information regarding the TV channels is separated therefrom, decoded and stored in the form of tuning data in a tuning data memory. Each tuning datum corresponds to one of these TV channels. In this manner the tuning data memory is automatically programmed, i.e. without the users' interposition, for all receivable TV programmes.

Apparatus using teletext to provide channel identification information

In order to obtain fast and simple processing of a recieved page address (65, 67, 69) into a write command (95) for a multi-page memory (99) of a teletext processing circuit, a page-number memory (81) is used which can be addressed by the received page address and in which a write command for the multi-page memory is stored for the desired pages.

Teletext signal processing circuit for a teletext receiver

An error correction circuit in a television receiver for receiving, for example, Teletext information, Viewdata information or information of comparable systems. The codes representing symbol information received by the receiver are classified into one out of two or more classes in dependence on the frequency of their occurrence, this classification being an indication of the extent to which it is probable that a received code is correctly received. In FIG. 1, a picture text television receiver has a receiving section, audio and video amplifiers 4 and 9 and a picture tube 10, 11. A text decoder 21 receives symbol information which is stored in a store 25 for display. An error detector circuit 40 including a comparison circuit 43 and two parity circuits 41 and 42, and checks for parity between newly received and already stored symbol information. A reliability circuit 60 is also included.

Error correction circuit using character probability

An effective control of the degree of suppression in a sound suppression filter in a television receiver is obtained when the required control signal is derived from the product of the amplitudes of the sound intercarrier signal and the chrominance sub-carrier signal, this product being in practice a measure of the disturbing difference frequency component between the chrominance sub-carrier signal and the sound intercarrier signal.

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Eindhoven, Netherlands

Wilhelmus J Christis