| 摘要 |
<p>The signal in each channel of a stereo is modulated at an inaudible frequency by a replica of the original signal. The modulated signal is broadcast into a room by a loudspeaker (48) and is picked up by a microphone (41). The microphone is coupled to the stereo, which includes a demodulator (51) for separating the replica from the signal as received at the microphone. By comparing (56, 66) the replica with the original signal, data is extracted to compensate for the acoustic characteristics of the loudspeaker and the room in which the loudspeaker is located.</p> |
