Costas signals are widely used in modern radar systems as frequency coded. The Costas-code-based waveform can achieve a nearly thumbtack shape of the ambiguity function (AF). However, the highest AF's sidelobe levels (SLLs) of Costas waveform equals just 1/ N times of its main lobe level height, where N is the length of the Costas code. In this study, the authors suggest a generalised Costas waveform as a ‘burst’ of weighted pulses having variable time spacing between them, calling it as weighted variable time spacing Costas (WVTSC). They computed the AF analytical formulas of the designed WVTSC. They developed an adaptation model to adapt the WVTSC to target scattering coefficients, using the interior-point algorithm. The adaptive WVTSC yields much better Doppler cut and improved delay cut in the main lobe area of the AF, in the sense of SLL reduction. Moreover, they constructed an optimisation model resulting in optimal variable time spacing between the sub-pulses. The optimised WVTSC also yields considerable improvement in the AF's recurrent SLLs, using the genetic algorithm. The adapted optimised WVTSC design is proven, through simulation, to have better sidelobe performance than that of the initial waveform, without influencing the original delay-Doppler resolution, and without need to increase N .

中文翻译：

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基于Costas码的雷达波形设计，使用具有目标散射系数的自适应权重和具有改进的歧义函数的最佳可变时间间隔

Costas信号以频率编码方式广泛用于现代雷达系统中。基于Costas码的波形可以实现歧义函数（AF）的近似图钉形状。但是，Costas波形的最高AF旁瓣电平（SLL）仅为1 / ñ 其主瓣水平高度的倍数，其中 ñ是Costas码的长度。在这项研究中，作者建议将广​​义Costas波形表示为加权脉冲的“突发”，它们之间具有可变的时间间隔，称其为加权可变时间间隔Costas（WVTSC）。他们计算了设计的WVTSC的AF分析公式。他们使用内点算法开发了一种自适应模型，以使WVTSC适应目标散射系数。从减少SLL的角度来看，自适应WVTSC在AF的主瓣区域产生更好的多普勒截止和改进的延迟截止。此外，他们构建了一个优化模型，从而在子脉冲之间产生了最佳的可变时间间隔。使用遗传算法，优化后的WVTSC还可以显着改善AF的复发性SLL。经过验证的经过优化的WVTSC设计已被证明ñ 。