通信工程文献翻译——摘要：土壤水分检测是自动灌溉控制系统的关键因素。 通过土壤探针测试下的恒流源，能够对土壤进行反应.A水分变化的电阻和电容组合模型研究。 根据模型，指出土壤水分的信号采样应尽可能接近瞬态过程的初始值，检测电路实现湿度脉冲宽度的转换，采用捕获脉冲宽度 方法可以准确得到湿度值，并且对于湿度变化非线性曲线，在自动控制系统中的检测控制策略中，经过实际测试，控制系统的设计具有良好的稳定性和分辨精度。

关键词：土壤水分检测; 容量模型; 检测电路设计; 控制策略

土壤水分，也称土壤含水量，是植物生长的重要因素。在园林花园和温室自动灌溉控制系统中，土壤水分检测的准确性和稳定性是控制系统成功的关键。现有的土壤水分测量方法基本上是电信号测量方法，也就是说，当土壤作为载体通过电信号时，电信号特性有一定变化。但实际土壤结构和组成非常复杂，土壤为固体，液体，气相组成的物质[1]，这些物质的平衡较弱。当探头插入土壤或电信号通过时，土壤中的平衡发生变化，使测量精度和稳定性差。在测量过程中如何确保稳定性和准确度是通过电信号测量土壤水分的关键问题。

1恒流源土壤水分模型

设计土壤水分检测结构如图1所示，使用直径约1mm，100mm长的不锈钢针作为土壤探针，探头之间的距离为100 mm。当控制开关打开时，恒流源输出稳定电流（0.5 mA），并在两个探头之间输出电压波形，以获得图2中的电压瞬变曲线。如果测量不同湿度的土壤，可以得到图2的曲线簇。

（1）在恒流源的作用下，土壤水分越高，输出电压波形的瞬态过程越长，输出电压振幅的变化越大。

（2）在恒流源条件下，当达到新的平衡时，输出电压的大小趋于一致。

（3）在恒流源的作用下，土壤水分越高，过渡过程中输出电压的初始值越小。 土壤水分越小，输出电压的初始值越大。

理论上，土壤水分检测的电气模型可以......

Abstract: Soil moisture detection is a key factor in automatic irrigation control system. Through the constant current source under the soil probe test, can be able to react soil .A Study on Resistance and Capacitance Combination Model of Moisture Variation. According to the model, it is pointed out that the signal sampling of soil moisture should be as close as possible to the initial value of the transient process and The detection circuit to achieve the humidity pulse width of the conversion, the use of capture pulse width method can accurately get the humidity value, and for the humidity change nonlinear curve to the Out of the automatic control system in the detection control strategy, after the actual test, the design of the control system has a good stability and differentiation accuracy.

Key words: soil moisture detection; capacity model; detection circuit design; control strategy

Soil moisture, also known as soil moisture content, is an important factor in plant growth. In the automatic irrigation control system such as garden flowers and vegetable greenhouses, the accuracy and stability of soil moisture detection is the key to the success of control system. The existing soil moisture measurement methods are basically the electrical signal measurement method, that is, when the soil as a carrier through the electrical signal, the electrical signal characteristics of a certain change. But the actual soil structure and composition is very complex, the soil is solid, liquid, gas phase composition of the material [1], these substances in a weak balance. When the probe is inserted into the soil or the electrical signal passes, the balance in the soil is changed, making the measurement accuracy and stability poor. How to ensure stability.......