Time-Frequency Joint Imaging Algorithm for Borehole Radar Logging

In borehole radar logging identification technology, there are two key issues: target detection range and spatial resolution. Existing imaging algorithms suffer from significant drawbacks, including poor imaging performance for long-distance targets, inadequate tracking performance for moving targets, and weak identification capability for small cross-section targets. To address the contradiction between detection range and resolution as well as the bottleneck in small target identification, we propose a novel joint time-frequency imaging algorithm. This algorithm includes key steps such as amplitude normalization, time-base synchronization calibration, multi-cycle signal superposition, hybrid-domain digital filtering, and time-varying amplification. Experimental results from extensive investigations show that our algorithm increases the target detection range from the decimeter level (traditional method) to the 10-meter level, and enhances the spatial resolution from the meter level (traditional method) to the centimeter level. The proposed algorithm provides crucial support for the development of a time-domain borehole radar logging system that achieves both long-distance detection and high resolution.