| 摘要 |
Information is transmitted between a transmitter, on board of an aircraft for example, having a PTT-key and a receiver, at an air traffic ground control station for example, by generating an AF signal at the transmitter with speech data from a speech transducer. The AF signal is converted into an RF signal and the transmission of the RF signal is initiated by activating the PTT-key. Additional data for transmission from the transmitter to the receiver is combined with speech data by suppressing a predetermined portion of an AF speech spectrum of the AF signal and embedding the additional data in the suppressed portion of the AF speech spectrum. The RF signal is demodulated at the receiver and used.
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