<title>Application of Rayleigh quotients for rapid classification of rotary-wing and fixed-wing targets using high-resolution radar signatures</title>

Abstract

Modern radar performs target recognition and target imaging tasks, in addition to conventional tasks of detection and tracking. New processing techniques, like stepped frequency wave-forms, modulation due to rotary parts, etc. and RF hardware are now becoming available and will soon result in lower-cost high resolution radar for commercial as well as military applications. Feature extraction, namely modulation due to rotary wings can be used to discriminate fixed wing verses rotary wing aircraft. Further advantage of wide band operation allows generation of synthetic range with resolution of few centimeters required for target identification. An important class of wave-forms used for high resolution mapping and target imaging, falls under the category called stretch wave-form processing. The simplest wave-form processing uses Fourier transform (FFT or IFFT). Range profiles thus generated, show the scattering centers of the target, and are being used for one-dimensional target identification procedures. These range profiles, however are very sensitive to target registration due to zero sampling inherent in the FFT procedure. This phenomenon together with the well known aspect sensitivity of the target profiles, plays havoc in the automatic target recognition procedures. In this paper we present a new method of obtaining range profiles or frequency spectrums. These spectrums do not sample zeros and are robust with respect to range motion or range registration. Based on the super-resolution techniques, analysis is given for the Rayleigh's Quotient procedure. It is shown that all the peaks of the range profiles are preserved and none of the zeros are sampled.