ApplicationNo. 05/970835 filed on 12/19/1978
US Classes:370/204, Plural diverse modulation techniques370/206, Quadrature carriers370/491, Pilot370/493, Combined voice and data transmission370/503, Synchronizing370/529Information superimposed on other information
ExaminersPrimary: Olms, Douglas W.
Attorney, Agent or Firm
International ClassesH04J 1/14 (20060101)
H04J 1/00 (20060101)
Foreign Application Priority Data1977-12-22 DE
AbstractIn a radio broadcoast channel, an additional message is superimposed on the normal message so as to be inaudible to the listener. To accomplish this, the additional message, consisting of digital signals, is modulated on a subcarrier lying in the ear-physiological masking range of the normal message. During breaks and very quiet intervals of the normal transmission, the signal transmission is interrupted because no masking occurs during those times. To make this possible, the transmission of the normal message is delayed by at least one signal length.