Fast methods of estimating ground scatter interference

A bounding method for estimating terrain interference using the three-dimensional model of terrain scattering and the normalized scattering coefficient is presented. Instead of using the brute-force method of integration, the bounding method partitions the integration region into two regions: one in which the integral is evaluated and the other in which it is bounded. If the bound is less than 10% of the value obtained by integration, the value of the estimated interference is replaced by the value obtained from the exact integral evaluated over a much smaller region. Otherwise, the region of the integration is increased and the bound over the smaller residual region is evaluated. Since this process can be repeated several times with decreasing residual regions and since the value of the bound is a monotonically decreasing function of the residual region this recursive process is convergent. The value of the interference can therefore be determined by integrating over a much smaller region than is presently done and using much less computer resources