Application of Wigner Distribution for the Detection of Accelerating Low-Altitude Aircraft using HF Surface-Wave Radar

摘要

Real radar data has been analysed using the Fourier transform method and the type-III Wigner distribution. The results show that whenever the target was detectable by the Fourier transform method, the target was detectable also by the smoothed type-III Wigner distribution method. In the other trials the target was not detectable by the Fourier transform method but the target was detectable by the smoothed type-III Wigner distribution method to varying degrees of success. Based on the analysis of real radar data, we conclude that the smoothed type-III Wigner distribution provides a promising method of detecting accelerating targets. However, more work has to be done to find an optimum smoothing method. It may turn out that different smoothing methods have to be used depending on the acceleration and the closeness of the target to the clutter region. Another important contribution of the present work is the use of the type-III Wigner distribution rather than the type-I Wigner distribution which has been used by many other researchers. When the type-I Wigner distribution is used, the range of unambiguously measurable normalized velocities is pi. Moreover, targets that are it radians away from the clutter region in the spectral domain will get masked by the clutter and cannot be detected. The type-III Wigner distribution helps us to overcome these problems. When the type-III Wigner distribution is used, the range of unambiguously measurable normalized velocities is 2 pi, and target that are it radians away from the clutter region can be detected.