Time domain reflecting soil moisture tester and measurement method

Abstract

The invention discloses a time domain reflecting soil moisture tester and a measurement method. The method comprises the following steps: dividing sine voltage signals of single frequency generated by a high-frequency sine voltage source into two paths of signals by using a signal distributor, transmitting one path of signals to a probe through a coaxial cable by a circulator and transmitting the other path to a phase detector through a delay cable; reflecting test signals at the probe and then returning the reflected test signals to the circulator through the coaxial cable; separating the reflected signals from incident signals by using the circulator and transmitting the reflected signals to the phase detector; and then converting phase differences between the incident signals and the reflected signals into direct current voltage signals in proportion to the phase differences by using the phase detector to detect the moisture content of soil to be detected. The time domain reflecting soil moisture tester can be technically implemented, has much lower cost than foreign products, is easy to popularize and apply in China and is proved to reach the level of the conventional TDR soil moisture tester through experimental check.

Description

technical field [0001] The invention relates to time-domain reflectometer technology, in particular to a time-domain reflective soil moisture tester and a measurement method based on the principle of phase detection. Background technique [0002] Time Domain Reflectometry (TDR) is one of the most advanced rapid soil moisture measurement technologies in the world today. Compared with other methods, TDR has the following advantages: 1) High precision, and the measurement error of volumetric water content is generally within 2%; 2) The measurement results are less affected by the soil type, and generally do not need to be calibrated separately for specific soils; 3 ) No radiation, less destructive to the soil; 4) The geometric structure of the probe has little influence on the measurement results; 5) Long-term automatic monitoring can be carried out in cooperation with the data recorder. The application of TDR instruments in foreign countries also plays an important role in mo...

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Problems solved by technology

[0026] Aiming at the problems that the traditional time-domain reflection soil moisture measurement method (TDR) is technically difficult and the system cost is high, the purpose of the present invention is to provide a new time-domain emission soil moisture tester based on phase detection, especially to provide a Use a single frequency sinusoidal signal instead of a step signal, use a phase detector to convert the phase difference between the incident signal and the reflected signal into a proportional DC voltage signal, without using the traditional TDR technology's fast step signal generator and high Time Domain Transmitting Soil Moisture Meter Based on Frequency Sampling Oscilloscope Technology

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