A real-time correction method based on time-varying zero offset for the equivalent sampling of ground penetrating radars

Echoes can be distorted due to the temperature drift of the ground penetrating radar (GPR) system,the low-pass effect of lossy media,and the decline in the coupling between the antenna and the ground.The mixing of effective radar echoes and zero-offset components makes it difficult to detect weak signals.The conventional front-end correction and post-processing methods,which aim to improve the transmission efficiency and remove the clutter noise,fail to improve the signal-to-noise ratio (SNR) and sensitivity of the system.To overcome these obstacles,this study improved the equivalent sampling circuit using a real-time correction method based on time-varying zero offset.Specifically,the zero-offset coefficient of each sampling was controlled separately and was updated in real time on each sampling.No DC and low-frequency components were sent into the subsequent programmable amplifier along with effective signals,ensuring the correct acquisition of weak signals and the dynamic range of the system.Experiments have proved the validity and feasibility of this method,which has been applied to a new type of digital GPR product.