A system for securely providing restricted display information having an encoder-transmitter for transmitting selected update data using information identification codes as enabling reception keys and a plurality of uniquely identified decoder-receivers for receiving the update data for display on a...http://www.google.fr/patents/US5321750?utm_source=gb-gplus-shareBrevet US5321750 - Restricted information distribution system apparatus and methods
Restricted information distribution system apparatus and methods
