A signal processing system comprises inputs for an analog audio signal and a digital data signal. The digital data signal is modulated to an analog data signal in an inaudible frequency band. Filters are used to ensure that the audio signal is restricted to audible frequencies and that the analog data...http://www.google.fr/patents/US5612943?utm_source=gb-gplus-shareBrevet US5612943 - System for carrying transparent digital data within an audio signal
System for carrying transparent digital data within an audio signal
