Ship And Maneuvering Target Detection Algorithm For Skywave Over-the-horizon Radar

High-frequency skywave over-the-horizon radar (OTHR) can detect ultra longrange targets and get the target information. It has the features of wide areassurveillance, low cost per unit area, anti low flying aircraft and anti stealth.Doppler frequency of ship targets is close to the sea clutter spectrum, theionospheric contamination will lead to the sea clutter broadening in Doppler domain,which will smear the neighbor ship target signals. To solve this problem, this paperproposed the phase gradient-singular value decomposition algorithm to correctionospheric distortion and suppress the sea clutter.The echo signal of ballistic missile target has the problem of Doppler aberrationand range migration, which will reduce the detection performance. This paper presentedthe high ambigulty fuction-envelope replacement method to improve the detectionperformance.The main work is as follows1. The distance demodulation scheme of OTHR is deducted in detail, and thesimulation results are given.2. This paper analysizes the impact of the ionosphere on electromagnetic wavepropagation, establishes the ionospheric phase contamination model. The HRRalgorithm, the polynomial phase transform algorithm and the phase gradient algorithmwere analyzed and simulated. The cascade algorithm of phase gradient and singularvalue decomposition is proposed to improve ship detection performance.3. This paper researches the acceleration compensation and signal detection ofmaneuvering target. Derived the general method of acceleration compensation. Giventhree algorithms to estimate the target motion parameters. With the advantage of highprecision and low computation amount, the HAF algorithm is widely applied.Unfortunately, the algorithm has a high SNR threshold and cross-terms. To solve thisproblem, the three phase function algorithm and fractional Fourier transform are usedfor maneuvering target detection.4. The characteristics of ballistic missile target in the boost phase has been analyzed, and a ballistic missile flight model has been established. For high velocity ofthe ballistic missile at the end of the boost phase, the range migration will degrade thecoherent integration gain. The detection algorithm based on envelope replacement isused to solve the problem and verified by simulation.5. The method for ballistic missile target detection of the boost phase is proposed.First the HAF algorithm is used to compensate the acceleration, then the envelopeinterpolation replacement algorithm is used to solve the range migration. Simulationexamples demonstrate that the proposed algorithm is suited for detecting ballisticmissile targets, aircraft target and two goals at the same time.