Soil Moisture Sensor Resonant Frequency Comparison
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Solution Overview
Problem
Conventional soil moisture measurement methods are cumbersome, time-consuming, and prone to inaccuracies due to complex equipment requirements and indirect frequency measurement techniques, which hinder real-time and precise moisture content determination.
Innovation Solution
A soil moisture sensor system that generates high-frequency signals in both a probe circuit and a reference circuit, comparing frequencies to accurately determine soil moisture content without varying the input signal frequency, and optionally includes a temperature sensor for compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional frequency scanning method is used to measure resonant frequency, then measurement can be performed, but measurement time increases and accuracy decreases due to indirect calculation
Solution Approach 1:
The patent replaces the conventional mechanical frequency scanning method with an electrical oscillation method. By using an oscillation circuit that naturally oscillates at the resonant frequency, the system directly measures frequency through electrical signal period detection rather than mechanical scanning, achieving both faster measurement and higher accuracy.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the oscillation circuit with components (capacitor, inductor, transistor) that enable the circuit to automatically oscillate at the target resonant frequency. This eliminates the need for sequential frequency scanning and allows immediate measurement upon circuit activation.
2Measurement precision
If complex frequency variation process is used, then resonant frequency can be measured, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the complex frequency variation process from the measurement system. By using a fixed oscillation circuit that operates at a predetermined frequency, the system removes the need for frequency modulation components and control mechanisms, simplifying the device while maintaining measurement precision.
Solution Approach 2:
The oscillation circuit serves itself by automatically generating and maintaining oscillation at the resonant frequency without external frequency control. The circuit self-regulates through its inherent feedback mechanism, eliminating the need for complex frequency variation equipment.
3Productivity
If conventional moisture measurement methods are used, then moisture content can be determined, but measurement speed is slow and equipment is expensive
Solution Approach 1:
The patent changes the measurement parameter from indirect methods (weight, conductivity, neutron radiation) to direct frequency-based measurement. By measuring the resonant frequency of the oscillation circuit that is influenced by soil moisture, the system achieves rapid measurement with simpler, less expensive equipment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid, accurate, and cost-effective real-time moisture content determination, reducing manufacturing costs and eliminating the need for complex frequency variation processes, while ensuring stability and precision.
Implementation Method 1
a resonance circuit whose resonant frequency changes in response to a change in the equivalent inductance attributable to a change in the moisture content contained in the soil
Implementation Method 2
measuring and comparing frequencies for the high-frequency signals in the two circuits
Data Source
AI summary
Disclosed herein are a soil moisture sensor and an operating method thereof. The soil moisture sensor includes a first probe including a pair of first electrodes extending in a first direction; a first resonance circuit connected to the pair of first electrodes of the first probe through a pair of first ports, and configured such that a first AC signal is applied thereto; a second resonance circuit having the same impedance as the first resonance circuit, and configured such that a second AC signal having the same characteristics as the first AC signal while being a reference AC signal is applied thereto; and a determination circuit configured to receive a first electrical signal and a second electrical signal and to determine the moisture in the soil based on the first resonant frequency of the first electrical signal and the second resonant frequency of the second electrical signal.