Adaptive filters for direct path and multipath interference cancellation: Application to FM-RTL-SDR based Passive Bistatic Radar

Passive Bistatic Radars (PBRs) are able to detect and track objects using reflections from foreign sources such as broadcast and/or radio communication stations. Direct path and Multipath Interference (DPI and MPI) are one of the major problems encountered in PBR systems. They are defined as signals received directly from the transmitter through the surveillance channel; which is only dedicated to receiving targets' echoes. Except their Doppler shifts, DPI, MPI and the received echoes are coherent. To filter these interferences, different adaptive techniques are considered in passive radars' literature. In this paper, we aim to evaluate the well-known adaptive filters as the Normalized Least Mean Square (NLMS) and the Recursive Least Square (RLS) by investigating their impact on the detection of FM (Frequency Modulation) passive radar based on a real source of signals using RTL-SDR (RTL2832U Realtek Software Defined Radio).