Abstract: An interactive television broadcast system comprises a source for broadcasting a plurality of television channels and data. A plurality of remote receiving units, each include a tuner to enable the unit to be tuned to receive a selected TV channel broadcast by the source, a processor responsive to data received from the source to determine the channel to which the unit is tuned, and a transmitter for sending information relating to the channel to which the unit is tuned to a common data collector.

Abstract: Apparatus for interactively generating a display signal. The apparatus comprises: a receiver (2) for receiving a broadcast signal (15), the broadcast signal comprising a plurality of datastreams each including image data defining a background object (22–270), and control parameters (28–39); a foreground computer generated imagery (CGI) device (3) for generating a foreground computer generated object (CGO); a mixer (4) for combining the foreground CGO with background object image data to generate the display signal; and interaction means (3) for receiving the control parameters from the receiver, monitoring the position of the foreground CGO, and adapting the display signal with reference to the monitored position of the foreground CGO and the received control parameters.

Abstract: An interactive broadcast system comprising a plurality of user interfaces each comprising a local clock signal generator. Each user interface delivers interactive applications to a respective user with reference to its respective local clock signal. A central control system broadcasts data to the user interfaces. The CCS detects adjustment of the local clock signals to identify fraudulent users.