| 摘要 |
PURPOSE:To obtain efficient sound by forming a signal by a single side band modulation where the amplitude modulation index is nearly 2 so as to eliminate distortion. CONSTITUTION:Since the interference between the two waves, a side band and a carrier is utilized in both cases utilizing a high frequency side band wave and a low frequency side band wave, no distorted component 2ws is generated. Further, if an asymmetric and undesirable double resonance peak around the resonance frequency as a center exists in the resonance characteristic of an ultrasonic wave element, only the undesirable characteristic is utilized. Moreover, only the upper side band is used, then the resonance frequency of the ultrasonic wave element has only to be at the outside of the audible band and this leaves more room for element selection. |
