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基于前导序列的突发通信载波同步算法 总被引:2,自引:0,他引:2
在突发通信中,载波同步技术是解调系统的核心和关键技术。给出了一种基于恒包络零自相关序列(CAZAC)作为前导的突发通信载波同步算法,该算法基于CAZAC序列零自相关特性,先用载波频差前向校正、载波相位前向校正进行载波初始同步捕捉,再用锁相环技术进行跟踪,能够在低信噪比下进行快速载波恢复。仿真结果表明,本算法的同步速度快,捕获的频率范围较宽。 相似文献
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突发模式PSK信号的联合载波位时钟恢复算法 总被引:3,自引:0,他引:3
快速载波和位时钟恢复是突发模式传送系统的一个关键因素。本文提出了适用于突发模式PSK信号捕获阶段的一种快速联合载波位时钟恢复算法。算法基于一个特定图案的前导字,采用前向结构直接、同时估计各个同步参数。可估计的载波频差范围是大的,约为符号率的,并且算法所需的计算负载非常低,适合数字硬件实现。仿真结果验证了算法的可行性和有效性。 相似文献
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针对高动态环境下扩频信号的载波捕获与跟踪问题,本文分析了多普勒频移对锁相环、锁频环以及环路滤波器设计的影响,以及高动态环境中载波快速捕获问题,在此基础上提出了一种数字复合软环的设计方法,计算机仿真结果表明这种数字复合软环能有效地解决载波快捕与精跟踪的问题. 相似文献
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基于离散傅里叶变换的高动态突发信号检测及频率估计 总被引:1,自引:0,他引:1
针对高动态突发通信应用环境,提出了一种新的基于频率域的突发信号检测及载波频偏估计算法,通过一次离散傅里叶变换( DFT)实现突发信号存在性检测及频率估计,并与经典Power-Law算法进行了比较。仿真结果表明:在低信噪比条件下,新算法检测信噪比门限改善超过1 dB,频率估计均方根误差小于符号率的1‰,并且对载波频偏及信号电平动态不敏感,实现结构简单,适合实时处理及工程应用。 相似文献
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针对大动态脉冲编码-频率调制(PCM/FM)遥测信号的载波频率同步,提出了基于快速傅里叶变换(FFT)及频谱重心的载波频率估计方法,并采用了频谱叠加及频谱截取的优化方法提高算法估计精度.相对于其他基于FFT的频率估计算法,频谱重心法有着更高的估计精度及更好的抗噪声性能,而且复杂度代价很小.仿真的均方误差结果表明,基于FFT长度为2048和2块叠加以及保留信号99.9%能量的频谱截取方案有最好的估计性能.在最大多普勒频率、多普勒一阶变化率及二阶变化率分别为0.5倍、0.3倍及0.2倍符号率的大动态条件下,基于频谱重心法的二阶锁频环能够较好地完成载波频率跟踪.误码率曲线表明,经过频偏校正后的多符号非相干解调(MSD)性能与无频偏情况相比,无性能损失. 相似文献
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As the synchronization of binary offset carrier (BOC) signals couldn’t be realized in high dynamic environment by traditional acquisition algorithms,an acquisition algorithm based on fractional Fourier transform (FRFT) and discrete polynomial-phase transform (DPT) was proposed.Firstly,the algorithm determined how to process the received signal according to the dynamic order obtained by the order operation.And then the acquisition was achieved by searching the spectral peak of the FRFT algorithm to obtain the estimation of dynamic parameters and code phase.Theoretical analysis and simulations show that the proposed algorithm eliminates the influence of second-order doppler shift rate based on original FRFT acquisition algorithm,which can successfully capture high dynamic BOC signals.The proposed algorithm further enhances the dynamic adaptability and anti-noise performance and has superior performance in detection probability and acquisition time in comparison with other algorithms. 相似文献
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正交相移键控(QPSK)调制解调方式广泛应用于深空通信、数字卫星通信等高速系统中,高动态QPSK信号具有较大的多普勒载波频偏,针对现有的解调算法对QPSK信号频偏估计范围小、精度较低等问题,提出了一种改进的高动态QPSK信号解调算法。该算法利用基于Zoom-FFT的Quinn频率估计算法对载波频偏进行估计,将频偏估计分为粗估计和精估计两个过程,对估计所得频偏进行补偿后利用Costas环完成载波同步。在MATLAB中对算法进行了仿真,仿真结果表明,该算法能够实现对高动态大频偏QPSK信号的有效捕获,与传统的解调方式相比,该算法对载波频偏的估计范围更大,且具有更高的频偏估计精度和更好的误码性能。 相似文献
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由于发射和接收机振荡器的不稳定或/和信道的多普勒效应,使载波同步与补偿成为QAM信号接收的关键环节。针对非协作通信中各类载波同步算法只能校正较小的频率偏移的局限,根据QAM信号的基本特点,利用传输符号的统计独立特性,提出了一种新的数字载波频率估计方法。该算法采用开环方式,不需要导频数据,可以估计较大的频率偏移;没有反馈环路,复杂度低,实现起来比较简单。同时,该算法作适当改进,可以直接用于载波的估计。计算机仿真结果表明:该算法可以较好地对各种QAM信号中存在的较大频率偏移进行估计并做补偿;适当改进后可以直接用于估计载波频率,估计效果良好有效。 相似文献
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Enrico Vassallo Monica Visintin 《International Journal of Satellite Communications and Networking》2002,20(6):391-415
Several carrier phase recovery schemes for Gaussian minimum shift keying (GMSK) modulated signals are derived and analysed in terms of squaring loss and acquisition time. Two bandwidths are considered for the GMSK signal: BTb=0.5 and 0.25, following the recommendations of the Consultative Committee for Space Data Systems. Pre‐encoding is assumed to remove the inherent differential encoding of the GMSK modulations. The carrier phase recovery schemes are derived from the approximate expression of the GMSK signal as an OQPSK signal or as the superposition of two OQPSK signals maximum a posteriori/maximum likelihood phase estimation is considered, with perfect clock reference; both non‐data‐aided and decision–directed schemes are analysed. Moreover, in the case of GMSK with BTb=0.25, an equalizer is also included in the synchronizer loop to remove inter‐symbol interference. High and low signal to noise ratio (SNR) approximations are considered to simplify the structure of the synchronizers. It is shown that, for the considered BTb values, the complex synchronizers initially derived do not provide any improvements over their simplified versions; the introduction of the equalizer for GMSK with BTb=0.25 leads to a better performance. Moreover, it is shown that GMSK with BTb=0.5 has a better performance than unfiltered OQPSK, which is better than GMSK with BTb=0.25. The SNR values above which the high SNR approximation turns out to be convenient with respect to the low SNR approximation are also given. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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A wireless body area network (WBAN) is a radio‐frequency‐based wireless communication technology that consists of a number of different sensor and actuator nodes interconnected with a body gateway. Considering the constrained resources in WBAN devices, simple and noise‐robust synchronization algorithms are required. Frame synchronization and frequency offset estimation are extremely important in the design of a robust WBAN receiver. In this paper, a detection strategy such as frame synchronization and frequency estimation is described in the WBAN system, which can improve the receiver performance. In doing so, algorithms are designed or chosen for the frame detection, carrier frequency offset synchronization, and joint fine‐time and phase‐offset estimation by exploiting the spike‐like property of the physical layer convergence protocol preamble and the frame structure in the WBAN system. The performance of the WBAN synchronization receiver is verified by computer simulation. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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高动态环境下的"北斗"导航信号含有较大的多普勒频率及其变化率,传统锁相环(PLL)在跟踪时难以保证较高的跟踪精度.在分析高动态环境下"北斗"信号模型的基础上,提出了一种基于交互式多模型-扩展卡尔曼滤波(IMM-EKF)的自适应滤波算法,对载波相位及其高阶分量进行估计.IMM-EKF采用多个跟踪模型来解决滤波过程中单个模型不准确的问题,并结合改进的Sage-Husa自适应算法,在线估计和修正过程噪声及测量噪声的统计特性,增强了滤波的稳定性.仿真结果表明,IMM-EKF相比于PLL和EKF,估计精度更高,算法稳定性更强. 相似文献