Abstract
Global navigation satellite system (GNSS) multipath signals received by a geodetic-quality GNSS receiver can be used to estimate the water content of soil around the antenna. The direct signals from satellite to GNSS antenna are the most valuable signals in geodetic measurement, such as positioning, navigation, GNSS control network, deformation monitoring, and so on. However, the GNSS antenna also captures the reflected signals from the ground, which contain information of surrounding environment, so that useful information about the reflection surface can be inferred by analyzing the reflected signal. This technique is termed as GNSS-interferometric reflectometry. The signal-to-noise ratio (SNR) data recorded by a receiver contains SNR component of reflected signals, which is related to the soil moisture of the ground. The changes of soil moisture content will cause the change of soil permittivity and reflectivity which are the key factors that make further change of the SNR of reflected signals. We used the measured data to evaluate the correlation between amplitude of multipath induced SNR time series and real soil moisture. An improved soil moisture estimation algorithm based on multipath induced SNR amplitude data is proposed in this paper. The performance of the proposed soil moisture estimation method is evaluated using the 15-month data recorded by PBO H2O GNSS station and a 14-day experiment in Wuhan, China. The experimental results show that the estimated soil moisture has a strong correlation with the real soil moisture and the estimation accuracy in terms of root-mean-square error (RMSE) is 0.0345 cm3cm−3 and 0.0339 cm3cm−3, respectively. Meanwhile, the application scope of the method is given.
Highlights
In addition to the basic functions of positioning, navigation, and timing, a global navigation satellite system (GNSS) can be utilized for a range of other applications including communications, surveillance, and remote sensing such as atmosphere sensing, earthquake monitoring, and deformation monitoring [1,2,3]
The direct and reflected signals can be received by a single GNSS receiver antenna and the technique is termed as GNSS interferometric reflectometry (GNSS-IR)
The main reason why GNSS-IR works is that the magnitude of the signal-to-noise ratio (SNR) time series recorded by receiver varies as the water content of the soil around the GNSS antenna changes [20]
Summary
In addition to the basic functions of positioning, navigation, and timing, a global navigation satellite system (GNSS) can be utilized for a range of other applications including communications, surveillance, and remote sensing such as atmosphere sensing, earthquake monitoring, and deformation monitoring [1,2,3]. The effect of plant coverage on reflected SNR data was observed so that the effect needs to be mitigated to achieve better estimation of the soil moisture [32]. This is in accordance with results of a field test experiment reported in [33]. The change in phase offset is affected by soil moisture, and satellite elevation, and the reflected signal signal-to-noise ratio (SNR) sequence is not a standard trigonometric function. More details about the proposed method will be described
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
