Efficient configuration calibration using ground auxiliary receivers at inaccurate locations

Abstract

The target localization accuracy is very sensitive to the knowledge of radar positions in an airborne distributed system. However, perfect knowledge of radar positions is generally unavailable, leading to the degradation in the target localization accuracy and furthermore the deterioration in signal coherence at the destination. Thus, this work deals with the configuration calibration problem in the airborne distributed system with the assistance of several ground auxiliary receivers (GARs) at inaccurate positions, such that absolute radar positions can be obtainable through jointly using the inter-radar direct path time measurements (DPTMs) and external DPTMs from radars to GARs. The analysis on Bayesian Cramer-Rao lower bound (BCRLB) affirms the required minimum of GARs is two for precise calibration, provided that the position of a radar and orientation from the projection of the radar on the ground to a GAR are known. It proceeds to introduce the idea of iteration and second-order Taylor series expansion to enable the formulation of the pseudolinear estimator relating radar and GAR positions. The previous work is also extended to a more practical scenario, where exact positions of GARs are inaccessible. Simulations confirm well with the theoretical developments.