Research On Ultrasonic Ranging Alarm System Of Hydrological Telemetry Platform Based On ARM

The good work of hydrological measurement and prevention has important significance to make better use of hydrology and water resources services for the modernization of production. Hydrological telemetry platform is the main hydrological mobile measurement equipment in the hydrographic survey work; According to actual needs, the real-time distance measured from the surface of the water to itself needs uninterrupted detection,not only povide reference data for mersurement of itself, but also provide protection for the safe operation of the telemetry platform. Research on ranging alarm system that can be used to hydrological telemetry platform is essential. Based on years of research efforts of hydrological automated measurement equipments by Taiyuan University of Technology, combined with the problems of actual measurement work of telemetry platform in primary hydrological station,the research on ultrasonic ranging alarm system of hydrological telemetry platform presented,in which system*embedded ARM processor used as control center, ultrasonic ranging technology of high accuracy and wide range transit time method [TOF], wireless data communications technology, liquid crystal display technology, sound and light alarm technology and key detection technology are all intergrated.The development principle of embedded ARM processor and theory of ultrasonic ranging are researched in this paper. Design of hardware circuit and software algorithms form two-pronged approach to improve the ultrasonic ranging accuracy and mersurement range from. In hardware design, according to the laws of attenuation of the ultrasonic energy, the time gain compensation (TGC) circuit is designed to compensate gain loss due to the increase of the measured distance; Peak time detecting circuit is designed to avoid echo leading edge detection error in echo signal processing; temperature compensation circuit is designed to reduce the influence, that ultrasonic propagation velocity in the medium affected by temperature; an adjustable three-tier classification ranging capabilities is designed to use, not only close-up of high-precision measurement is achieved, but also a large range of long-distance ranging becomes possible. The delay timing method is used in the software design in order to avoid the interference of aftermath signal and reduce the minimum measurement distance (blind spot); the median method algorithm is used to reduce the error caused by data jitter; step-by-step approach method is used to set the TGC gain value in different distance.Sound-light alarming function of system limit Location is realized by buzzer buzzing and bright LED light flashing, frequency of buzzing and flashing, which means alarming distance; key detection function is designed to adjust the alarm limit. The ranging information displayed by LCD12864with backlight and Chinese font. In the field of modern instruments design, problems of communication and data storage is crucial, RS232serial ports are designed for communicate with hydrological telemetry platform and communicate with upper pc though wireless data transmission modul. The capability of measured data receiving and storage is realized.Finally, the experiments have carried on the system; the system has a good application performance verified by experimental results:distance form telemetry platform to the surface of water measured accurately, measurement results displayed clearly, alarming accurately when reaches the limit position, communicate with upper PC stablely. And various technical indicators have reached the research requirements.