The factors affecting the threat level of the target are analyzed in amphibious assault ship (AAS) to air self-defense.And the attribute values of each factor are quantified.The weights of each factor are determined by combination weighting method based on entropy eveluation method and analytic hierarchy process (AHP).According to the weapon performances of AAS and the situation at that time,the incoming air targets are further divided into four categories.On this basis,the threat assessment model of AAS to air self-defense is established.Finally,two typical situations are designed for simulation calculation and the results show the model is economic.

Orthogonal frequency division multiplexing (OFDM) radar signal has good resolution and high spectral efficiency; and OFDM radar signal based on chaotic binary-phase coded modulation is widely favored due to its flexible structure, better pulse compression performance and strong anti-jamming capability. However, the high peak-to-average power ratio in the system makes the OFDM radar limited in practice. A selective mapping (SLM) algorithm based on chaotic particle swarm optimization (CPSO) is proposed to reduce the peak-to-average power ratio for the OFDM radar signals modulated by different chaotic binary-phase coding sequences. The experimental results show that the SLM algorithm based on CPSO has better effect in reducing the peak-to-average power ratio of OFDM radar signal than traditional SLM algorithm and basic particle swarm optimization SLM algorithm.