Fast Extensive Cancellation Algorithm in Passive Radar Signal Processing

In the processing of passive radar, the signals used are typically not designed for radar systems. Consequently, the high clutter floor induced by these signals can obscure the target, making it challenging to detect targets of interest. To address this issue, various clutter suppression algorithms have been developed to improve the signal-to-clutter ratio (SCR), among which the Extensive Cancellation Algorithm (ECA) plays a crucial role. ECA projects signals onto a direction orthogonal to the clutter space to suppress it, but calculating the orthogonal operator requires matrix multiplication and inversion, resulting in significant computational load. In this paper, we introduce the Fast ECA (FECA), which is theoretically equivalent to the ECA and can also be applied to various signal formats. By reusing the orthogonal operator, FECA significantly reduces the time complexity. Furthermore, we propose two flexible suppression frameworks to apply FECA, and its performance is validated in simulation scenarios, particularly highlighting its advantages in time complexity. Finally, we apply FECA to real-world data, where it successfully uncovers targets that were previously hidden beneath a clutter-induced ambiguity floor, confirming the practical utility of the algorithm in complex, large-scale clutter environments.