| 摘要 |
PROBLEM TO BE SOLVED: To provide an efficient method and a device to distribute and receive information in a communication system application, such as digital audio broadcasting(DAB). SOLUTION: Audio information is distributed to a user in a partially encrypted form by an in-band on-channel(IBOC) DAB system of multi-stream type. The information is coded, divided into a plurality of bit streams, and at least some of them are left uncoded. These plurality of bit streams correspond to the sub-bands of at least first and second digital sidebands of a host carrier signal. Both the encrypted and unencrypted bit streams are received by the user and stored in a storage device. The user is allowed to access to information of a first quality level during restricted period can listen to and record the information with FM quality, without an encryption key by using only the unencrypted bit stream. |
