Nonlinear filters for long range radars

Accurate estimation of the state vector of ballistic missiles tracked by long range radars is an important and difficult nonlinear filtering problem. In particular, the problem of ldquofalse cross range observabilityrdquo is discussed in, and essentially the same problem is addressed in. The radars of interest are phased arrays with ranges of thousands of kilometers, as described in. As explained in, the measurement error volume of such radars are highly non-Gaussian in Cartesian coordinates, and the degree of non-Gaussianess becomes more severe at longer ranges and with improved range measurement accuracy, owing to pulse compression. This paper was written for normal engineers, who do not have homotopy for breakfast.