Research On The Data Acquisition System For Acoustic Signal Of Leaking Water Supply Pipes

With the rapid development of the world population and economy, the waste of water resources has become one of the main factors which restrain the development of social economy. Every year, our country suffers an astonishing loss because of water supply pipeline leak. The water leak not only wastes the precious water but also creates huge economic loss. The main research purpose of the experts who are engaged in the water supply pipeline jobs is to provide effective leak detection methods and instruments for the pipeline engineers.This paper develops a data acquisition system for acoustic signal of leaking water supply pipes. According to the needs of leak localization, this system has the function of signal conditioning, data acquisition and transmission, USB communication, liquid crystal display, etc. It provides the essential data for the signal processing of the leak detection.Based on the theoretical research on the leak acoustic signal and correlation positioning as well as LMS time delay estimation, this paper studies the noise influence on the variance of time delay estimation, gives some methods to suppress the noise both from leak detection environment and system circuit. As the system often carries on the field operation, the data acquisition system also have low power consumption.In this paper, SCM (Single Chip Microprocessor) is selected to be the master control unit. After analyzing the demands of noise and power consumption, we presented the integral design scheme of the data acquisition system. As the amplitude of leak signal is varied with the pipe internal pressure and leak situation, band pass filter and programmed gain amplifier are used to improve signal acquisition ability and reduce the quantization error. USB is adopted to realize fast order and data transmission. Liquid crystal display is used to enhance the system man-machine interaction ability. The embedded software is designed by using C language ,and liquid crystal display character model is established manually. Software programming thought has also been introduced.The tests of the circuit noise and power consumption indicate the system has achieved the low noise, low power consumption design goal. The experiments of the filter effect and the ADC effective number of bits testify the system can suppress the out-band noise effectively. At last, we apply the data acquisition system to the water pipe leak detection, experimental results show that the system can collect the leak signal correctly and meet the signal processing needs of leak detection and localization.