DIGITAL TELEVISION SYSTEM

摘要

PROBLEM TO BE SOLVED: To attain communication between a CA module or a decoder without providing the built-in CA module or a special connector to a television receiver or the decoder by connecting the CA module to a communication network bus so that the communication among a signal source, the CA module and the television receiver or the decoder is executed via the bus. SOLUTION: A television receiver 2 provided with a decoder 3 is connected to a bus 1 and a digital television signal from a satellite receiver 4 is sent to the bus 1. Decoding of the coded digital television signal is conducted by a conventional method through cooperation between a CA module 5 and a smart card 6. The communication between the decoder 3 and the CA module 5 is executed by a protocol in use via the bus 1. Thus, no special connector to connect the CA module to the television receiver 2 or the decoder 3 is required and a digital video recorder 7 uses the CA module 5.