CAM (Conditional Access Module)
This module contains the decryption algorithms for pay tv. You put this module into your receiver and your smartcard into the module. This scheme makes it possible to use one receiver for more than one pay tv. Most pay tv receivers which are built for pay tv, contain two of those slots. You have to buy the module seperatly. They cost from 100-300 US$.
System which use CAMs: Irdeto, Viaaccess, Cyrptoworks and some others more.