Nonbiased geometric centroid for high resolution radar angle tracking

An efficient algorithm is presented for tracking the true and nonbiased geometric centre of an array of scatterers on a single target. This algorithm is specifically designed for the monopulse radar angle tracking system with stepped frequency pulse train. The crosscorrelation function of the sum and difference channels normalised by the autocorrelation of the sum channel is used to calculate the geometric centre of each uniquely separated pair of scatterers. Dividing by the autocorrelation function eliminates the effects of different targets radar cross-sections (RCS), however, the zero separation term of the error function (DC term) is still biased toward the bigger scatterer. The nonzero terms (AC terms) are the down range distance separations between scatterers and are independent of their RCS. By simply dropping the zero separation term, and averaging the remaining terms together, the aim-point becomes the unbiased geometric centre of the array