RFI Suppression for Synchronous Impulse ...

This paper focuses on suppression of Radio FrequencyInterference (RFI) for ultra-wideband (UWB) radarsignals, sampled using the synchronous impulse reconstruction(SIRE) time equivalent sampling scheme. This equivalent sampling scheme is based on the Army Research Lab’s (ARL) efforts to build an ultra-wideband (UWB) radar in forward looking mode that samples returned radar signals using low rate andinexpensive analog-to-digital (A/D) converters. The cost effectiveness of this SIRE UWB radar makes it plausible for actual groundmissions for detecting buried explosive devices. However, the equivalent time of sampling scheme complicates RFI suppression as the RFI samples are aliased and irregularly sampled in real time. In this paper, the RELAX and multi-snapshot RELAX algorithms are presented as an intermediate step to the previously proposed averaging scheme by the Army Research Laboratory, in order to enhance RFI suppression for this sampling scheme. The proposed suppression technique involves modelling the narrow band RFI signals as a sum of sinusoids and applying the afore mentioned algorithms. The RELAX algorithm improves the RFI suppression performance without altering the target signatures compared to AR modelling. The multi-snapshot RELAX algorithm which provides a more accurate sinusoidal model than the RELAXalgorithm, improves on the RELAX algorithm in terms of suppression. However, the target signatures are suppressed as the number of sinusoids increases. The analysis of the algorithmsis was performed by using collected sniff (passive) data using the SIREradar in addition to simulated wide-band echo signals (pointtargetsignatures).