Research On Radar Level Gauge System Oriented To Open Channel Irrigation

The serious waste of irrigated water resources is a significant issue facing China’s agricultural water.To solve this problem,"water saving priority" is used as the working policy.By ameliorating existing agricultural irrigation methods,water resources are utilized scientifically,and macro and micro distribution capacities of water resources are improved.The remote automatic control metering diversion gate project combines the concepts of water saving priority and scientific water use with agricultural irrigation practice to construct a reasonable,efficient and automatic irrigation water distribution system.This system can regulate the flow of the branch irrigation channel according to the real-time demand of downstream irrigation water consumption.Present,the remote metering gate system needs to measure the water level of the main channels in the irrigation area and monitor the hydrological status of the main irrigation channels in real time.The non-contact radar water level gauge is an effective way to solve this problem.The following aspects are completed in this dissertation:The working principle of FMCW radar was analyzed,and the triangular wave was selected as the modulation signal of radar input.The overall scheme of radar level gauge was designed,including the radar sensor,STM32F4 series main control,modulation wave generation,signal processing and communication modules as well as the software system.The design of the hardware circuit primarily contains the modulation waveform,difference frequency amplification,high-pass filter,inverse proportional amplification,low-pass filter,voltage bias,STM32 minimum system,RS485 communication and individual power supply circuits.The design of the software system was completed,including the overall design of the software system,the digital waveform generation,ADC sampling,and data processing programs along with the experimental testing of each module.The overall functional test of the radar level gauge was completed and tested in indoor and simulated irrigation channels.Through on-site experiment and debugging of indoor and simulated irrigation channels,the experimental data in the range of 2 meters to 15 meters were compared and analyzed.It was concluded that the radar water level gauge can satisfy requirements of the remote metering gate system for the water level measurement of the main open channels in the irrigation area while achieving the expected design goals.