FIELD: security equipment. SUBSTANCE: in order to prevent illegal use of subscription card 5 for private television by a person who found or stole it, data for identification of user is stored in protected read-write area. When usage of new card 6 starts, transmitter 2 compares identity of new card and old one and outputs control signal only if both identification signals are same. EFFECT: increased security. 6 cl, 2 dwg
