Enhanced visibility of maneuvering targets for high-frequency over-the-horizon radar

This paper describes a processing algorithm based on high-order ambiguity function (HAF) that increases visibility of maneuvering targets in HF over-the horizon radar (OTHR). For the presence of the echo backscattered by the target that has significantly varying radial velocity within a coherent integration time (CIT), it is difficult for traditional coherent processing to centralize energy and peaks in Doppler spectrum. Due to the polynomial phase property in the Doppler spectrum of maneuvering target radar echo, HAF is introduced as an efficient parametric tool to estimate the parameters of the polynomial-phase model. And a compensation process follows to eliminate the coherent integration loss (CIL) caused by irregular motion of target. Finally, this method is generalized to the case of multiple maneuvering targets. The corresponding information of acceleration and higher-order radial components after motion decomposition can be extracted directly and is benefit for consequent missions, such as detection and tracking. The experimental results are given to illuminate the validity and efficiency of the proposed method.