Adaptive optimum attitude extrapolation for precise antenna pointing control

An adaptive attitude extrapolator is described for the precise control of an airborne radar antenna. The extrapolator is an optimum design that provides extrapolation output with minimal mean-square angular prediction error. The effects of INS (inertial navigation system) attitude measurement noise, aircraft maneuver, and environmental gust condition are automatically taken into account. Because the extrapolation filter coefficients are computed on the basis of a real-time estimate of the aircraft attitude motion autocorrelation lags, it is capable of adapting to the varying operating conditions. Analysis and simulation results show a significantly lower antenna pointing error with the use of the adaptive extrapolator than with the conventional deterministic attitude extrapolator. The adaptive extrapolator is applicable to airborne phase-array radar systems making monopulse angular measurements for which the precise pointing of the radar antenna is crucial