Author :
Ghouz, H.H.M. ; Elghany, F.I.A. ; Qutb, M.M.
Abstract :
For pt.I see ibid., p.B8/1-B8/8 (2000). In phased array radar systems, a tracking process is performed using an electronic scan of a predetermined sector to provide a continuous information about the detected targets. In practice, the presence of interference (noise, clutter, and jamming signals) either prevent or deceive the tracking circuit to follow the real targets, and consequently, the tracking process is terminated. This paper presents an adaptive technique of filtering to suppress the interference in phased array tracking radar systems. The aim is to provide a key feature for discrimination between the desired and the interference signals. Unlike the time processing techniques, the present filtering process is based upon the target Doppler shift as well as the interference spatial distribution to suppress adaptively the undesired signals. This technique of filtering is referred to as adaptive coherent space-time (ACST) filter. The objectives are to investigate and evaluate in detail the performance of the adaptive filter under different interference environments. This includes total intercepted power, type and spatial distribution of the interference. The spatial covariance matrix of the interference is estimated using the direct matrix inversion (DMI) algorithm. Then the optimum Wiener solution for the adaptive filter is obtained. The results of our simulation show that an appreciable improvement in the signal to interference plus noise ratio at the filter´s output “SINRo ” is obtained. Also, the filter´s performance is very sensitive to the interference type that has a direction either coincident with or close to the desired signal direction. In this case, a trade-off between the filter´s complexity and the minimum SINRo required for a continuous target tracking should be considered. In conclusion, the presented filter is an attractive and robust solution for solving the tracking problem of low target RCS immersed in interference (e.g., stealth aircraft)
Keywords :
Doppler shift; adaptive filters; covariance matrices; filtering theory; interference suppression; jamming; matrix inversion; noise; phased array radar; radar clutter; radar cross-sections; radar tracking; space-time adaptive processing; target tracking; SINR; adaptive coherent space-time filter; adaptive filter performance; adaptive filtering; adaptive space-time processing; clutter; desired signal direction; detected targets; direct matrix inversion algorithm; electronic scan; filter complexity; interference; interference environments; interference signals; interference spatial distribution; interference suppression; interference type; jamming signals; low target RCS; noise; optimum Wiener solution; phased array tracking radar systems; signal discrimination; signal to interference plus noise ratio; simulation results; spatial covariance matrix estimation; spatial distribution; stealth aircraft; total intercepted power; tracking circuit; Adaptive filters; Covariance matrix; Filtering; Interference suppression; Phased arrays; Radar detection; Radar tracking; Signal processing; Signal to noise ratio; Target tracking;
