An improved SDIF algorithm for anti-radiation radar using dynamic sequence search

In the traditional anti-radiation radar detection, a crucial task is to separate the useful target radar signal from random overlapping pulse flow. The Time Difference Of Arrival (TDOA) histogram is an effective tool for pulse train de-interleaving, however, the classic Sequential Difference (SDIF for short) histogram algorithm cannot deinterleave the PRI jittered signals efficiently, since the statistics of the TDOA can be easy to be affected by PRI jitters, and thus prone to the loss of targets. Then, in order to improve the robustness of the SDIF, an improved SDIF algorithm is proposed, where the overlapping PRI bins are adopted and can detect the PRI jittered signals, however, in some cases, it might lead to multiple PRI estimations that actually belongs to only one target. As a second step of the signal sorting, in the sequence search algorithms after the estimation of PRI, the velocity of the traditional direct sequence search algorithms is not fast enough since multiplication operation is involved in this signal processing procedure. Also, it requires detail information of the first pulse in the traditional sequence search algorithms such as curve fitting, and even worse, the multiplication operation is involved, these limitations reduced the radar signal processing speed directly. In order to overcome these deficiencies, and to deinterleave PRI jittered signals quickly and accurately, in the paper, an improved SDIF algorithm based on dynamic sequence search is proposed. By introducing the overlapping box and dynamic sequence search algorithm based on classic SDIF method, it no longer requires the precise information of the first pulse, and no multiplication operation is needed. Besides, the entire searching procedure turns out to be in linear form and fast. Consequently, this algorithm has the characteristics of anti-interference and is able to overcome the pulse loss factor. An illustrative simulation is present to verify the proposed method. The results showed that the algorithm can well deinterleave the PRI jittered signals with jitter quantity within 10%, which is useful in real application in the modern warfare circumstance.