| 摘要 |
PURPOSE:To increase the maximum modulation frequency by setting the width of a modulation frequency to + or -(0.05-0.05)fc in an ultrasonic wave transceiver. CONSTITUTION:A center frequency is limited to 40kHz in the ultrasonic wave transmitter whose adjacent resonance frequency exists in the range of + or -(0.03- 0.25)fc to the center frequency fc and the modulation frequency is observed while using the modulation width as an object. In setting the maximum modulation frequency to 1,500Hz, the effective modulation width changes from + or -0.005fc to 0.04fc and the maximum modulation frequency being >=4,000Hz is obtained. |
