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Record companies like to ensure that radio and nightclub DJs have new music
releases ready to play on the official release day. The problem is that if
records go out in advance, some DJs can be tempted to break the embargo. So
Warner Music in the US is planning to prevent this electronically (WO 01/15428).
A batch of music CDs for DJs will be encrypted so that they can only be played
back on a modified player. The encryption is time-coded and the key tied to the
official release date. To stop DJs cheating the system by moving on the clock in
the player, the time code is beamed down from the fleet of 24 GPS satellites
orbiting the Earth. So everyone around the world gets to start playing their
records at the very same time.