Calibration concept for a GPR monitoring system and methods for arrival time picking

Calibration of ground penetrating radar (GPR) measurement systems is indispensable to enable quantitative and high resolution data analysis especially for high resolution soil research as well as inversion approaches for a wide range of applications. This work presents a concept for an in situ calibration of GPR monitoring systems which enables to perform a calibration that is not solely based on signals traveling in air. A classical calibration via signals traveling in air is not feasible in our setup, since the system is permanently positioned around a test specimen, e.g. a soil column. The calibration concept is based on the ability to use each antenna as both transmitter or receiver and, thereby, perform reciprocal measurements. Initial test measurements indicate the reliability of reciprocal measurements for an in situ calibration of our monitoring system with relative accuracies of down to 2 ps.