摘要
本文提出一种以对连续波进行锁相来实现声速测量的方法。它利用压控振荡器的正弦信号在介质中产生连续超声波,然后将来自相隔一定距离的超声波发射点和接收点的两个信号输入鉴相器,鉴相器的输出经低通滤波后即成为压控振荡器的控制电压。这样的锁相环路所锁定信号频率能保证发、收两点间的距离与超声波波长之比为固定值,该频率反映了声速的大小。文章介绍了使用本方法,以斜探头产生的表面波对钢带和钢筋进行的声弹性测量试验;和用收发一体化换能器对特殊形状螺栓所作的轴向力测量试验。试验情况表明,锁相法使超声波频率能灵敏地跟踪介质中声速的变化,而且还能对四端网络传递函数极点位置进行锁定和跟踪。
A method of continuous wave phase-locking for sound speed measurement is proposed in this paper. Continuous ultrasonic wave is generated in the medium by the sine signal of a ACO. The control voltage of VCO is the output of a low-pass filter, which is connected to the output of a phase discriminator, having two input signals from tramsmitting and receiving points of ultrasonic wave pla- ced at some distance apart. The signal frequency locked by the phaselocked loop makes the ratio between the distance from the transitting point to the receiving point and the wavelength of the ultrasonic wave constant. This frequency is a measure of sound speed. Some experiments using this method are presented. The results of experiments show that using this method the frequency of ultrasonic wave can track the variation of sound speed in a medium sensitively and can lock and track the apotheosis position of a quadipole transfer function.
出处
《海洋技术》
1991年第2期53-59,共7页
Ocean Technology
