| The space environment around the earth is becoming more and more complexwith the increasing of space activities, and the phased array radars with multiple targetobservation ability are playing an important role in space target detection and tracking.However, against the weak targets which are tens of thousands of kilometers awayfrom the ground or have small RCS, the traditional phased array radars are powerless.To improve the performance of phased array radar for the weak target detection,accumulation is required to be performed over time to gather sufficient energy.Considering both the multi-target observation ability of phased array radar andthe fast calculation method with FFT of coherent integration, a quasi-random pulsetrain echo model is presented in this paper first, which divide the pulse train into a fewsub-pulse-trains (time is uniform within the sub-pulse-train while nonuniform amongsub-pulse-trains). Then, this article proposes four coherent integration algorithmsbased on this model. Algorithm I, II, IV are coherent integration algorithms whilealgorithm III is associated coherent-noncoherent integration algorithm. Algorithm I issuitable for the completely nonuniform pulse train while algorithm II, III, IV can beapplied to this model only. We conclude the principles in practical application forselection of the four algorithms according to the theoretical analysis of integrationperformance and computational complexity, and the simulation analysis andexperimental verification. Finally, we present the application of phased array radar inintegration and detection for the weak space target based on its lead orbit.According to the research, algorithm II can reach a better performance when theinterval between sub-pulse-trains is small, and algorithm IV can obtain a betterperformance when the interval between sub-pulse-trains is big, and algorithm III canget an outstanding performance in the aspect of computation and sensitivity to theintervals among sub-pulse-trains. |
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