Coherent integration for targets with constant Cartesian velocities based on accurate range model

Abstract

Long-time coherent integration (LTCI) is one of the most important techniques to improve radar detection performance of weak targets. In the existing LTCI methods, polynomial models with finite terms are used to formulate signal model. However, for the targets moving with constant Cartesian velocities (CCV), infinite polynomial terms are required to precisely describe target range evolution. The model mismatch may lead to performance degradation and limitation on integration time and coverage of target speed. Here, a novel generalized Radon Fourier transform method for CCV targets is presented, based on the accurate range evolving model, which is a square root of a polynomial with terms up to the second order with target speed as the factor. The accurate model instead of approximate polynomial models enables effective energy focusing on characteristic invariant with feasible computational complexity. The target samplings are collected and the phase fluctuation among pulses is compensated according to the accurate range model. The high order range migration and complex Doppler frequency migration caused by the highly nonlinear signal are eliminated simultaneously. Integration results demonstrate that the proposed method can not only achieve effective coherent integration of CCV targets regardless of target speed and coherent processing interval, but also provide additional observation and resolution in speed domain.