Receive-Coherent Synthesis Method of Moving Target for Airborne Distributed Coherent Aperture Radar Based on Parameter Space Division

Airborne distributed coherent aperture radar (ADCAR) benefits from the signal coherent synthesis of multichannel echoes to improve signal gain and detection performance significantly. However, the complex detection environment formed by the geometrical configuration between ADCAR and the region of interest always causes distance–velocity envelope shifts with different properties and relative phase deviations, severely reducing the signal coherent synthesis efficiency. We make contributions toward addressing these limitations. First, the signal model and description of target coherent parameters (TCPs) for ADCAR in the receive-coherent (RC) stage are considered, and a parameter space division using the dimensionality reduction (DR) condition for TCPs is proposed. Then, a multiple transmit–receive pairs joint TCPs estimation method based on maximum likelihood estimation is proposed, and the RC synthesis strategies are performed with the DR and non-DR conditions by the proposed TCPs estimation method. On this basis, two fast implementations based on particle swarm optimization and conjugate gradient are proposed for the RC synthesis and the TCPs output. Finally, the results of simulation experiments and real-measured data indicated that the performance of the proposed methods for signal coherent synthesis, TCPs estimation, and target detection is significantly improved compared with the traditional methods.