Soil moisture measurement unit and method

Abstract

The invention relates to a soil water content measuring instrument and a method. The instrument comprises a pulse signal generator for generating a pulse signal and transmitting the pulse signal to a measurement probe; the measurement probe for reflecting at the start end and the tail end after receiving the pulse signal to respectively generate two pulse reflection signals; a pulse detection circuit for detecting and sampling the two pulse reflection signals provided by the measurement probe to obtain two sampled pulse reflection signals; and a micro-control unit for obtaining the water content per unit volume of soil according to the two sampled pulse reflection signals. According to the invention, time domain reflection resulting from impedance mismatch between the start end and the tail end of the measurement probe is formed by using the pulse signal, and the actual water content per unit volume of the soil to be detected can be obtained by measuring the time difference of mirror reflection waves. The invention has the advantages of high measurement speed, high accuracy, low cost, easy batch production, etc.

Description

technical field [0001] The invention relates to the field of high-frequency measurement, in particular to a soil moisture measuring instrument and method. Background technique [0002] In the process of agricultural production, soil not only provides physical support for plant growth, but also serves as a nutrient bank for plant growth. Water is the lifeblood to ensure the growth of crops. A series of reactions in the soil, energy and material exchange are all related to water, which is directly related to crop yield and quality. TOPP (1980) gave the approximate relationship between soil dielectric constant and soil moisture content through experiments, called TOPP formula, and practice has proved that this experimental formula can achieve higher accuracy under different types and compositions of soil conditions ( 0.022m3m-3, Jacobsen and Schjonning, 1994). Therefore, the research on the measurement method of soil moisture content based on soil dielectric properties has at...

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Problems solved by technology

However, since the length of the soil probe usually does not exceed 20cm, the reflection time difference based on the TDR measurement principle based on soil moisture is much smaller than the reflection time difference of the cable fault diagnosis and location, and the conventional reflection measurement technology cannot realize the soil moisture instrumentation design.

So far, the soil moisture measuring instruments based on the TDR principle basically use the step pulse with a steep front as the excitation signal. The key technology for measuring the reflection time difference is not yet mature, and the soil moisture instrumentation design cannot be realized.

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