Soil Moisture Measurement Method Based on TDR Using Phase Detecting Technology
Time domain reflectometry (TDR) is widely used in soil moisture measurement due to its advantages of high accuracy and stability. In this paper a new method is presented to determine soil moisture based on TDR using phase detecting technology (called P-TDR). Single-frequency sinusoidal voltage signal was adopted as test signal to replace voltage pulse with very short rise-time, i.e. phase detector was used instead of high-speed sampling oscilloscope for P-TDR. The phase error between reflected signal and incident signal was measured in order to calculate the travel time of test signal along the probe embedded in moist soil, from which the soils volumetric water content will be inferred. The system shows high accuracy and resolution in travel time measurement. Through calibration, measuring deviations is less than 0.02m3/m3 between P-TDR system and standard gravimetric sampling method,which can be achieved in loam soil with volumetric water content up to 0.5m3/m3.
soil moisture time domain reflectometry dielectric constant phase detecting
WANG Kedong WANG Yiming
College of Information and Electrical Engineering,China Agricultural University, Beijing 100083, P.R.China
国际会议
2008 International Conference on IAEA(2008农业信息化、自动化与电气化国际会议)
镇江
英文
717-721
2008-11-01（万方平台首次上网日期，不代表论文的发表时间）