用于星间通信的高灵敏度快捕算法

High sensitivity fast acquisition algorithm for inter-satellite communication

摘要:

为实现微小卫星快速协同工作,满足星间通信链路对扩频信号捕获算法提出的高灵敏度与快速捕获的要求,对常用捕获算法的原理进行分析,针对传统信号捕获方法存在的捕获灵敏度低、捕获时间长、信噪比要求高等缺陷,提出一种适用于星间链路的FFT快速捕获算法,该算法在传统FFT码相位捕获法的基础上通过多路并行架构、特殊同步序列、降速率抽取、非相干累加等优化策略对传统算法的捕获灵敏度及捕获速度进行改善。基于对改进算法的可行性进行检验,首先通过理论公式推导了算法的极限灵敏度、抗干扰能力与理论捕获时间,其次,在MATLAB软件中设置典型任务环境对算法的各项性能进行仿真,最终通过搭建硬件测试平台对算法进行性能实测。仿真及硬件测试表明:该算法相对于传统捕获算法性能有明显提升,改进算法的极限捕获灵敏度可达-130 dBm,捕获时间小于100 ms,符合卫星通信环境设计需求,并已在自主研制的天平二号卫星的星间通信机中验证了其可行性；改进算法还可通过调节算法的并行路数、非相干累加次数等算法要素兼容不同应用环境需要。

Abstract:

In an effort to achieve the rapid cooperation of Either micro-satellites or microsatellites and meet the requirements of high sensitivity and fast acquisition of spread spectrum signal proposed by inter-satellite communication link, the principle of common acquisition algorithms was analyzed. In view of the shortcomings of traditional signal acquisition algorithms such as low acquisition sensitivity, long acquisition time and high signal-to-noise ratio requirements, a fast FFT acquisition algorithm for inter-satellite link was proposed. Based on the traditional FFT code phase acquisition method, the algorithm improves the acquisition sensitivity and acquisition speed of the traditional algorithm through multiple parallel architecture, special synchronization sequence, rate reduction decimation, incoherent accumulation and other optimization strategies. In order to test the feasibility of the algorithm, firstly, the limit sensitivity, anti-interference ability and theoretical capture time of the algorithm were derived through theoretical formula. Secondly, the typical task environment was set in MATLAB software to simulate the performance of the algorithm. Finally, the performance of the algorithm was measured by building a hardware test platform. Simulation and hardware tests show that the performance of this algorithm is significantly improved compared with the traditional acquisition algorithm. The ultimate acquisition sensitivity of the improved algorithm is -130 dBm, and the acquisition time is less than 100 ms, which meets the design requirements of satellite communication environment. Its feasibility has been verified in the inter-satellite communication machine of the self-developed tianping-2 satellite. The improved algorithm can also be compatible with different needs of applications in various environments by adjusting the number of parallel paths, non-coherent accumulation times and other elements of the algorithm.