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Abstract

GNSS reflectometry has been proved to possess the capabilities for deformation monitoring by observing the carrier phase difference between the direct and reflected signals. However, to obtain the carrier phase measurement, the requirements to signal quality and monitoring geometry is relatively strict, and the application of this method is limited because of the requirement of continuous observation and the involvement of software defined radio (SDR) receiver. We present an innovative deformation monitoring method of observing signal-to-noise ratio (SNR) oscillation pattern of the interference of direct and reflected signals, by using daily repeated GNSS-R data. The direct and reflected signals were merged by radio frequency combiner, then fed into an off-the-shelf commercial GNSS receiver. Then the SNR of the interference signal can be directly outputted and recorded, and the oscillation pattern between observation days have been aligned by geometry model, and the phase shift of the oscillation pattern can be analyzed for deformation monitoring. The field experiment results show sub-centimeter level accuracy with more than 300 meters monitoring range. This new method possesses the advantages of robust, low data size and computational burden, and long monitoring range. Especially, without need of continuous observation and applicable for commercial GNSS receiver make this method more practical for long-term quasi-static deformation monitoring.