直扩MSK调制解调技术研究
发布时间：2019-01-26 07:35
【摘要】：最小频移键控(MSK)调制结合扩频通信体制,具有MSK信号的优点和扩频通信技术截获概率低、保密性好、抗干扰能力强的特点,在战术数据链、导弹制导指令数据传输、民用航空地空数据链、卫星通信等领域得到了广泛应用。因此,开展直扩MSK调制解调技术研究具有重要的理论意义和应用价值。本文研究了伪随机序列特性,选择拥有良好自相关和互相关特性的Gold码作为扩频码。提出串行直扩MSK调制方式,推导直扩MSK信号的线性表达式,设计了直扩MSK调制及解扩解调实现方法,通过仿真分析验证直扩MSK调制及解扩解调方案设计的可行性及其性能。详细研究并分析了高动态下直扩MSK信号的捕获和跟踪技术。对基于匹配滤波器的常规码捕获方案进行改进,通过两级码捕获平衡捕获时间与硬件复杂度,采用双差分相干码捕获法优化捕获性能。针对高动态扩频系统中存在的多普勒频移,选用FFT算法进行频偏估计,针对FFT频谱估计在低信噪比下性能不佳的问题,提出基于多普勒频率补偿-频域匹配的直扩信号快速捕获算法,改善了低信噪比下码捕获性能。使用全数字非相干超前-滞后延迟锁定环实现码跟踪,详细讨论了环路参数ζ和BL对码跟踪环路性能的影响。采用科斯塔斯(Costas)载波相位跟踪方案,推导出环路鉴相特性,通过仿真验证科斯塔斯环可有效的实现载波相位跟踪。
[Abstract]:The minimum frequency shift keying (MSK) modulation combined with spread spectrum communication system has the advantages of MSK signal, low probability of interception, good confidentiality and strong anti-jamming ability of spread spectrum communication technology. It is used in tactical data link, missile guidance and instruction data transmission. Civil aviation ground-air data link, satellite communication and other fields have been widely used. Therefore, the research of DS MSK modulation and demodulation technology has important theoretical significance and application value. In this paper, pseudorandom sequence characteristics are studied, and Gold codes with good autocorrelation and cross-correlation characteristics are selected as spread spectrum codes. This paper presents a serial direct spread MSK modulation method, deduces the linear expression of the direct spread sequence MSK signal, designs the realization method of the direct spread sequence MSK modulation and despreading demodulation, and verifies the feasibility and performance of the design of the direct spread sequence MSK modulation and despreading demodulation scheme by simulation analysis. The acquisition and tracking techniques of DSSS MSK signals under high dynamic conditions are studied and analyzed in detail. The conventional code acquisition scheme based on matched filter is improved. The dual differential coherent code acquisition method is used to optimize the acquisition performance by balancing the acquisition time and hardware complexity. In view of the Doppler frequency shift existing in the high dynamic spread spectrum system, FFT algorithm is used to estimate the frequency offset, and the FFT spectrum estimation has poor performance under low SNR. A fast acquisition algorithm for DS signals based on Doppler frequency compensation-frequency domain matching is proposed, which improves the performance of code acquisition under low SNR. The full digital incoherent lead-lag delay locking loop is used to realize the code tracking. The influence of the loop parameters 味 and BL on the performance of the code tracking loop is discussed in detail. The characteristic of loop phase detection is deduced by using Kostas (Costas) carrier phase tracking scheme. The simulation results show that Kostas loop can effectively realize carrier phase tracking.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN915.05
本文编号：2415267
[Abstract]:The minimum frequency shift keying (MSK) modulation combined with spread spectrum communication system has the advantages of MSK signal, low probability of interception, good confidentiality and strong anti-jamming ability of spread spectrum communication technology. It is used in tactical data link, missile guidance and instruction data transmission. Civil aviation ground-air data link, satellite communication and other fields have been widely used. Therefore, the research of DS MSK modulation and demodulation technology has important theoretical significance and application value. In this paper, pseudorandom sequence characteristics are studied, and Gold codes with good autocorrelation and cross-correlation characteristics are selected as spread spectrum codes. This paper presents a serial direct spread MSK modulation method, deduces the linear expression of the direct spread sequence MSK signal, designs the realization method of the direct spread sequence MSK modulation and despreading demodulation, and verifies the feasibility and performance of the design of the direct spread sequence MSK modulation and despreading demodulation scheme by simulation analysis. The acquisition and tracking techniques of DSSS MSK signals under high dynamic conditions are studied and analyzed in detail. The conventional code acquisition scheme based on matched filter is improved. The dual differential coherent code acquisition method is used to optimize the acquisition performance by balancing the acquisition time and hardware complexity. In view of the Doppler frequency shift existing in the high dynamic spread spectrum system, FFT algorithm is used to estimate the frequency offset, and the FFT spectrum estimation has poor performance under low SNR. A fast acquisition algorithm for DS signals based on Doppler frequency compensation-frequency domain matching is proposed, which improves the performance of code acquisition under low SNR. The full digital incoherent lead-lag delay locking loop is used to realize the code tracking. The influence of the loop parameters 味 and BL on the performance of the code tracking loop is discussed in detail. The characteristic of loop phase detection is deduced by using Kostas (Costas) carrier phase tracking scheme. The simulation results show that Kostas loop can effectively realize carrier phase tracking.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN915.05
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