Analyzing the Effective Coherent Integration Time for Space Surveillance Radar Processing

Coherent integration is an effective method to improve the detection sensitivity of a radar system. While a number of useful coherent integration algorithms exists, the critical question of determining the length of the coherent processing interval (CPI) often remains unanswered. In this paper, we present a practical approach to calculating the CPI length for a space surveillance scenario. Our approach takes into account the fluctuating RCS and the dynamic trajectory of a target in the low Earth Orbit. We simulate the target using a 3D CAD model and model its trajectory using a Keplerian orbit. The target RCS is estimated using physical optics method with the help of POFACETS 4.1 software. We calculate the CPI length based on the RCS correlation width and the accuracy of the target motion model by demanding that the maximum possible phase error remains below an allowed tolerance. The results show that integrating beyond the proposed limit is computationally inefficient and does not increase the SNR gain.