| 摘要 |
PURPOSE:To execut reproduction and amplification of a narrow band, by amplitude-modulating a carrier wave of an ultrasonic band by a signal of audio frequency, and inputting this signal to an acoustic transducer having non-linearity. CONSTITUTION:An audio frequency band electric signal is inputted to a terminal 1. A carrier wave electric signal generator 3 has oscillation frequency of an ultrasonic frequency band. An amplitude modulator 2 amplitude-modulates a carrier wave of the ultrasonic frequency band by an audio frequency band electric signal, and applies it to an acoustic transducer 5 whose input/output characteristics have non-linearity, through an amplifier 4. From the transducer 5, only a fundamental wave component of an input audio frequency electric signal and the second higher harmonic component can be listened. In this way, the band width of the transducer 5 can be made small, therefore the transducer 5 is designed easily. |
