Abstract: Method of transmitting picture data from a transmitter to a selected receiver. The picture data to be transmitted are split up into specific picture data intended for an individual receiver and common picture data intended for a plurality of receivers. The common picture data is stored in each receiver and the specific picture data is transmitted via a transmission medium. In the receiver, the specific and common picture data are combined to form a combined picture for display on a display screen. In a further embodiment, the common picture data is transmitted via a further medium, for example teletext.

Abstract: In a local communication system a frame forming device is provided which makes it possible to connect signal sources that are designed to have a private connection to a destination device (and therefore produce signals that are unspecific for selection of destination devices), via a shareable bus to the destination device. To determine to which destination device a signal source is connected, the frame forming device contains an address generator. By making functions of the address generator programmable via the bus the system connections are made flexible.

Abstract: A communication system is described comprising different buses which are interconnected via one or more gate connecting elements. There is a transmitter station transmitting a frame that comprises a target address field and one or more destination address fields. If the send and receiver stations are connected to the same bus, the contents of the target address field are sufficient to define the receiver station. In other cases the target address field defines a gate connecting element, whereas the latter fills the the target address field with the contents of one of the other fields. In this way receiver station addresses, which have already been defined on a previous bus, can again be used on the next bus. Furthermore, in a short-frame format, receiver stations on the same bus as the transmitter station can be addressed with very low overhead.

Abstract: A ring-shaped TDM digital communication system and method for enabling stations connected thereto to obtain access to a common message channel available for all of the stations. Access is unambiguously determined by an arbitration procedure which selects the station which obtains access to the message channel and excludes all other stations. Such message channel is also used for the arbitration procedure, which is based on recognizing the channel as being unoccupied if the value of the information in a time slot field thereon remains the same in successive cycles around the ring of a TDM frame comprising such field. The messages which are transmitted are structured so that error detection and correction, addressing, congestion indication, etc., can easily be included.