基于误码检测机制的滴灌系统红外光雨水传感器的设计

降雨使作物生长土壤中的水分含量增加而营养成分含量降低,智能化滴灌系统必须感知降雨的开始和结束,并对灌溉系统中的水分与营养成分进行相应调整与控制,既节水节能又保持作物良好生长环境。雨水水流对红外发射器和接收器间光通信产生散射干扰,并造成误码。该文设计一种基于误码检测机制的红外光雨水传感器,它由集雨器、导流管、红外光发射器和接收器组成,微控制器检测通信误码感知降雨,解决了传统雨水传感器在滴灌系统应用中只能监测降雨的开始而不能监测降雨结束的弊端。该文提出降雨时通信误码率最大,无降雨时通信误码率最小的数据码选择方法,该方法表明,数据码"1"码数目对通信误码率影响显著。试验结果表明,检测降雨最优码是255。该传感器对连续水流检测的误码率大于0.9983,对离散水滴检测的误比特率是0.7742至0.8307,该传感器对雨水的感知性能优于传统雨水传感器。

Design of infrared rain sensor of irrigation system using error detection mechanism

Rain will increase water content and reduce nutrition in the soil. Intelligent drip irrigation system is able to predict the beginning and ending of rain, and control the water-nutrition proportion in the irrigation system, thus saving water usage and building an optimum growing environment for crops. However, rain may disturb the communication between infrared transmitter and receiver, and cause errors in communications. A new error-detection-based infrared rain sensor was designed, which consists of a rain trap, a water tube, an infrared transmitter and receiver. The microcontroller can detect rain with the error in communication, while traditional rain sensors can only detect the beginning of rain, but not the ending. In addition, a method was proposed for optimal communication code selection, which was the selected code resulting in the largest error byte rate (EBR) when it was raining and the least EBR when it was not. The method showed that the code "1" had a significant effect on the EBR. Both theoretical analysis and experiments results proved that the optimal code was "255". Further experiments showed that the correction detection rate was larger than 0.9983 for continuous water flow, and between 0.7742 and 0.8307 for water drops. It is proved by experiment results that, the proposed sensor is better than the traditional rain sensors.