High Resolution Radar techniques are applied to the problem of resolving a multiple target array and locating its geometric center without the usual biasing toward the brightest targets. Monopulse radar techniques are combined with high resolution stepped frequency pulse train signal processing in an amplitude tracking radar. A single pulse monopulse system's aimpoint is biased toward the brightest point targets in an array. However, by using a stepped frequency pulse monopulse radar, the cross range distance to each individual scattered may be found. Unlike the single pulse monopulse system, the aimpoint is independent of the reflectivity of the targets. The geometric center of a multiple scattered array is found by averaging the cross range components along both axes. For the stepped frequency high resolution monopulse system, the center of each uniquely separated pair of point targets is calculated by examining the cross-correlation function of the sum and difference channels. The autocorrelation of the sum channel is used to normalize the cross-correlation data thereby eliminating the effects of the different targets radar cross sections (RCS). The zero separation term of the error function (DC term) remains biased toward the bigger scattered, even after normalization. The nonzero terms (AC terms) are the cross range distances from the antenna's boresight to each scattered and are independent of their RCS. By simply dropping ones together, the aimpoint becomes the unbiased geometric center of the array. The special cases of one, two and three resolvable point scatterers are examined in detail. Analysis of a nondiscrete complex scattering array is not presented, since the requirement of separation pair uniqueness cannot be assumed. The monopulse tracking simulation work was done on an IMB AT using Microsoft Fortran-77.
Available at: http://works.bepress.com/alan_young/98/