The Nearly-Linear Theoretical Model Inversion Of The Soil Moisture Based On The GNSS-R

GNSS-R (GNSS-Reflections or GNSS-Remote Sensing) technology since the1990s and gradually developed a new branch, which in the country and abroad is to detect the field of remote sensing and navigation technology research hotspot. GNSS reflected signal inversion of soil moisture is the use of satellite remote sensing of Earth signals the direction of the surface vegetation specific applications, is a passive bistatic multiple-based remote sensing technology.The reflected GNSS navigation signals by the surface carry characteristic information of the reflection surface,such as GNSS signal waveform, polarization characteristics amplitude, phase and frequency parameters of the inversion analysis of the physical characteristics of the reflecting surface, so processing and receiving data to accurately estimate the reflection of GNSS signals is key to the use of GNSS-R for soil moisture inversion. In this paper, making use of soil moisture retrieval experiment is based on FPGA+DSP architecture, commissioning and successful implementation of GNSS-R receiver hardware intended function, roughness analysis of soil moisture in the concrete need to consider temperature, soil surface and under the premise of different soil moisture status and other factors on the dielectric constant influence on GNSS reflected signals, the design of the experimental soil moisture retrieval and completed experiments in space provided by the National Institute of vegetables using GNSS-R receiver as the main experiment hardware equipment, through direct satellite signals and carry reflective surface characteristics of the reflected signal receiving and processing, the use of the ICF model inversion results were analyzed to obtain significant results, the feasibility of the use of GNSS reflected signal inversion of soil moisture, lay the foundation for Nearly-Linear proposed theoretical model. Nearly-Linear theoretical model that was nearly linear measurement model inversion data of each satellite soil moisture at five different regions, the establishment of a database, the database by each satellite data stored in the reflected power at different soil moisture after fitting the curve obtained for each satellite at different soil moisture normalized mean treatment directly in the subsequent inversion of the soil, the direct use of the measured power of the reflected signal to a theoretical model for the inversion of the soil, the model eliminates the complicated steps of traditional use GNSS-R for soil inversion through the Fresnel reflection coefficient and dielectric constant intermediate variables and then push the soil volumetric water content, and at the technical level is highly innovative and realizability.