Spatial adaptive filtering for LPI signal detection

Summary form only given, as follows. This paper presents two algorithms for jointly detecting and direction finding (DF) low probability of intercept (LPI) signals based upon spatial adaptive filtering concepts: adaptive event processing (AEP) for narrowband short duration (SD) signals and spatial spectral whitening (SSW) for wideband direct sequence spread spectrum (DSSS) signals. AEP jointly exploits spatial and temporal differences between consecutive observation intervals to null narrowband interference, evaluate an energy-based detection statistic, and upon detection compute a DF estimate of a newly turned-on signal. SSW exploits both spatial and spectral differences between the DSSS signal-of-interest (SOI), which has a constant direction of arrival (DOA) over a wide spectral extent, and strong spectrally localized interference to simultaneously form a decision statistic and a DF estimate. Aspects of both algorithms are discussed, and data obtained from a four element wideband array operating in the HF band is used to illustrate performance