Proportional Navigation on Nonstationary Targets

In a missile flying a proportional navigation course, the missile heading rate is made proportional to the indicated line of sight rate. While for stationary targets the resulting differential equations of motion can be readily integrated, this is no longer the case for moving targets. To obtain closed-form expressions convenient for the evaluation of trajectory parameters, the assumption is made in this paper that for moving targets, the angular rate of the closing velocity vector is made proportional to the line of sight rather than the actual heading rate.     

Optimum Cross-Coupled Tracker for Pulse-Doppler Radar

Although there is a well-defined relation between range and range rate, in conventional pulse-Doppler tracking radars the range-gate and frequency control loops are usually closed independently. In this paper, the optimum cross- coupled stationary tracking filter is derived, in which the range error signal is used to boost the frequency loop, and vice versa. The filter is derived for a general case of target dynamics and uncorrelated white noise in both the range gate and frequency control channels. It is shown that its tracking performance is superior to that of the conventional uncoupled tracking loop for reliable frequency channel operation. In solving the usually difficult degenerated Riccati matrix equation, a simple solution is obtained by applying the method of completion of the square to matrixes.