| 摘要 |
PROBLEM TO BE SOLVED: To correctly detect a signal component even if the S/N of an echo signal is low by synchronizing and integrating the echo signal and taking out a component signal in synchronization with the ultrasonic synchronization being transmitted by a transmitter/receiver and eliminating a noise component. SOLUTION: The output of a preamplifier 10 receiving an echo signal from a transmitter/receiver 3 is inputted by a synchronous integration circuit 13. Then, an X component signal where a signal being taken out of switches SW1 and SW2 is added is integrated by an integration circuit 132, and a Y component signal where a signal being taken out of switches SW3 and SW4 is added is integrated by an integration circuit 133. Integrated result is inputted by an operator 17, and the signal component of echo waves is detected and the level of a reflection surface 4 is calculated. In this case, by integrating the X component signal, a wavelength and an area being sandwiched by time axes are obtained and the integral value of the Y component signal is 0. Therefore, with the synchronous integration of the synchronous integration circuit 13, the integral value of only a frequency component that is equal to an ultrasonic frequency being transmitted by the transmitter/receiver 3 is calculated, the integral value is equal to 0 in other frequency components, and noise components are eliminated. |
