Alternative scheme for guidance signal filtering in a strapdown seeker

Abstract

A new scheme has been proposed for mitigating noise contamination in the guidance signal (line of sight rate) of a strapdown active electronically scanned array (AESA) seeker which occurs due to the coarse resolution of the beam shifter. An earlier work has been reviewed and its shortcomings, which include difficulty of implementation and sensitivity to the gain of the monopulse angle measurement subsystem, have been discussed. The above shortcomings of the earlier work have been eliminated in the proposed scheme where a signal is tapped from an accessible point and passes through an additional path in the signal processing loop of the strapdown seeker. Using the proposed scheme, the impulsive noise due to the finite resolution of the beam shifter (and bit transition spikes) can be completely eliminated in the nominal condition for any arbitrary transfer functions of the seeker blocks, without adversely affecting the bandwidth/speed of response of the extracted line of sight rate signal. The scheme also has reasonable performance under off-nominal conditions. Efficacy of the proposed scheme has been demonstrated quantitatively with examples of nominal and off-nominal conditions.