How do you control who can play back movies sold on pay-per-view? British recording engineer John Metcalf has a possible solution: a system that lets people watch what they download 鈥� but only in their own homes (World Patent WO 2004/44670).
Metcalf鈥檚 idea relies on the falling cost of GPS: the new set-top box has a GPS satellite positioning receiver card inside it which works out the set-top鈥檚 longitude and latitude. When someone buys a movie, it is encrypted and can only be unlocked when the set-top box verifies that its GPS coordinates are the same as those the subscriber gave when signing up for the pay-per-view service.
