Abstract:
A control information message is communicated from a control information generator and encoder (3) in a server installation (1) to one or more computer installations (2) by encoding the message into a single sequence of a relatively short duration, which is incorporated into an overall audio or video information carrying signal and transmitted to the user computer installation through a wired or wireless transmission media. In the user computer installations the received signal sequence is retrieved from the overall signal and decoded into the original message which is then used to initiate an action controlled by a prestored program in the user computer installation (2).