System for broadcast of data in an audio signal by substitution of imperceptible audio band with data

摘要

A system for broadcasting data (D) that can transmit information in the passband of a broadcast audio-frequency signal (S). The system can determine at least one frequency band (F'.sub.13, . . . , F'.sub.24) and the amplitude (A'.sub.13, . . . , A'.sub.24) of the audio- frequency signal (S). The system compares this amplitude with an auditory masking level (Nm(13), . . . , Nm(24)) associated with this frequency band and eliminates the frequency components of the audio-frequency signal in the frequency band if the amplitude of the signal is lower than the auditory masking level of the band. The system can insert the data in this frequency band at a level lower than or equal to the auditory masking level of the frequency band.