For many years a soil water content sensor with low cost, reliability and sufficient accuracy has been desirable. Thus, an improved measurement method based on the frequency domain (FD) principle for determining soil ...For many years a soil water content sensor with low cost, reliability and sufficient accuracy has been desirable. Thus, an improved measurement method based on the frequency domain (FD) principle for determining soil water content was considered. Unlike other measurement principles, a new measurable index, η, which was independent of the output impedance and the amplitude of the oscillator while relying on the electrical impedance of a multi-pin probe, was pro- posed. Moreover, a model for processing the impedance of the multi-pin soil probe was developed, and several important electrical parameters for establishing their operating ranges applicable to this probe were evaluated. In order to confirm the theoretical analysis, an experiment was conducted with a 4-pin probe. Using the developed model, the relationship between the proposed index η and soil volumetric water content was shown to be linear (R2 = 0.9921). Thus, as the measurable index, η seemed satisfactory.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 30270775 and 30370823) and the DoctorResearch Foundation of the Ministry of Education of China (No. 20030019012)
文摘For many years a soil water content sensor with low cost, reliability and sufficient accuracy has been desirable. Thus, an improved measurement method based on the frequency domain (FD) principle for determining soil water content was considered. Unlike other measurement principles, a new measurable index, η, which was independent of the output impedance and the amplitude of the oscillator while relying on the electrical impedance of a multi-pin probe, was pro- posed. Moreover, a model for processing the impedance of the multi-pin soil probe was developed, and several important electrical parameters for establishing their operating ranges applicable to this probe were evaluated. In order to confirm the theoretical analysis, an experiment was conducted with a 4-pin probe. Using the developed model, the relationship between the proposed index η and soil volumetric water content was shown to be linear (R2 = 0.9921). Thus, as the measurable index, η seemed satisfactory.
