True root mean square value detection-based soil moisture sensor

A technology of true RMS and soil moisture, applied in the direction of using microwaves to test moisture content, instruments, measuring devices, etc., it can solve the problems that the length of the probe should not be too long, limit the depth range of the soil layer, etc., and achieve simple input and output interfaces. The effect of low consumption and simple structure

Active Publication Date: 2011-04-20
SOUTH CHINA AGRI UNIV
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Problems solved by technology

However, at present, most of the various commercial dielectric soil moisture sensors are needle-type structures. This structure has the characteristics of simple geometric structure and convenient manufacture. However, due to the influence of the strengt

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  • True root mean square value detection-based soil moisture sensor
  • True root mean square value detection-based soil moisture sensor
  • True root mean square value detection-based soil moisture sensor

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[0031] The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0032] like figure 1 Shown is a schematic block diagram of a soil moisture sensor based on true RMS detection of the present invention, which is mainly composed of a power supply filter circuit and a square wave excitation signal generation unit connected in sequence, a signal attenuator, a probe and a true RMS detection The device is composed, and the power filter circuit is connected with each unit.

[0033] The power supply filter circuit is used to reduce ground potential jumps and power supply noise, and provides stable and ripple-free working voltage for each unit in the circuit; the square wave excitation signal generating unit is used to generate square wave signals;...

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Abstract

The invention relates to a true root mean square value detection-based soil moisture sensor, which comprises a power supply filter circuit, an active crystal oscillator, a Schmidt trigger, a signal attenuator, a probe and a true root mean square value detector. The Schmidt trigger shapes a high-frequency sine wave or square wave signal output by the active crystal oscillator into a standard waveform square wave signal, the amplitude of the standard waveform square wave signal is reduced by the signal attenuator, a resistor-capacitor (RC) circuit consisting of the signal attenuator and the probe is charged and discharged periodically, a periodic charging and discharging curve waveform is obtained on the probe, and the true root mean square value detector converts a waveform signal on the probe into equivalent direct current voltage serving as a sensor output signal. When soil moisture is different, the equivalent capacitance of the probe is different, the charging and discharging waveforms are different, and the final output signals are different, so that the soil moisture is measured according to the principle. The soil moisture sensor has the characteristics of simple structure, small volume, low power consumption, low cost, high soil adaptability, simple input/output interface and the like, is easy to apply and facilitates the development of secondary instruments.

Description

technical field [0001] The invention relates to the technical field of soil moisture measurement, in particular to a soil moisture sensor based on a dielectric method and high-frequency signal true effective value detection. Background technique [0002] Soil moisture is one of the important factors affecting the growth of crops, and it is closely related to the growth status of crops. In precision agricultural production, long-term monitoring and timely acquisition of moisture content information in the soil are required to achieve precise irrigation, so as to meet the physiological water requirements of crops without wasting water resources. This requires a soil Moisture testing device. [0003] The measurement methods of soil moisture are: drying method, neutron method, resistance method, capacitance method, TDR (time domain reflection method), FDR (frequency domain reflection method) and SWR (standing wave method). The drying method has high measurement accuracy, but s...

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Application Information

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IPC IPC(8): G01N27/60G01N22/04
Inventor 洪添胜李加念岳学军冯瑞珏李震文韬刘志壮
Owner SOUTH CHINA AGRI UNIV
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