| 摘要 |
In a system of prior art utilizing a feature of the hearing system, that is, the masking effect, a data signal is added into a digital audio signal. A transmitter transmits all information required for separating the combined signal on a separate data channel. The channel-coding causes, however, that data bits hidden in the audio signal are lost. This can be avoided in that in the transmission end the audio signal is channel-coded and immediately thereafter it is decoded and the samples thus obtained are compared with the samples obtained by delaying the audio signal by the delay of the channel coder and the coder. Only in the bit locations which remained unchanged in the encoding/decoding process, substituting data bits are placed. Information about the location of said bits is transmitted on the data channel. <IMAGE> |
