A communication system for a digital television system including an interactive response system (20) in communication with a television (10) of the digital television system (40) is described. The interactive response system (20) is arranged to accept an input from a user in response to an output signal...http://www.google.com.au/patents/US20020147986?utm_source=gb-gplus-sharePatent US20020147986 - Interactive response system for digital television
