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数字锁相环技术在恢复位时钟中的应用 总被引：3，自引：0，他引：3
详细介绍了如何在FPGA中利用VHDL语言实现超前滞后型数字锁相环,以便从位流数据中恢复出位时钟;并指出了其结构参数对于环路性能的影响。 相似文献
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USB2.0高速实时数据采集系统的设计与实现 总被引：2，自引：0，他引：2
介绍了一种基于USB2．0的高速实时数据采集系统的硬件及固件程序设计方案,及在不同的DSP、单片机之间移植固件程序的方法和调试过程中可能出现的问题及解决办法。 相似文献
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A generalized ionospheric dispersion simulation method is presented to verify and test wideband satellite-ground-link radio systems for dispersion robustness. In the method, ionospheric dispersive effects on wideband radio waves are modeled as an allpass nonlinear phase system, thus greatly decreasing the need for signal priori information. To accurately simulate the ionospheric dispersion and reduce the implementation complexity, the system is decomposed into three new allpass subsystems: with a linear phase passing through zero frequency, a constant phase, and a nonlinear phase with zero-offset and quasi-parabolic form respectively. The three subsystems are implemented respectively by the combination of integer-interval delay and fractional delay filter, digital shifting phase and the complex-coefficient finite impulse response (FIR) filter. The ionospheric dispersion simulation can be achieved by cascading the three subsystems in a complex baseband and converting the frequency to a radio frequency. Simulation results show that the method has the ability to accurately simulate the ionospheric dispersion characteristics without knowing the signal priori information and has a low implementation complexity. 相似文献
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Modified implementation architecture for sinusoidal frequency modulation is introduced to extract the range information from the received radar echo. Range ambiguity problem arises because the range is calculated from the estimated phase of the received signal which is wrapped into （0, 2π]. By integrating Doppler frequency shifts, the variation of range can be estimated and used as an auxiliary information to help eliminating the corresponding range ambiguity. The performance of the new technique is evaluated by simulations. The results show that this technique is robust to sever phase noise and can be used effectively for ambiguity elimination of the modified sinusoidal frequency modulated continuous wave radar. 相似文献
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The si mulation of radar echo is a dynamic pro-cess,including generation,transmission and process-ing of the radar echo.Many techniques,such assemiconductor,computer and signal processing areusedin the process of si mulation.The si mulation ofradar echo is a combination of the digital si mulationtechnique and the radar technique.Its basic tech-niques include the computer and signal processingtechniques.Its object is to test the algorithmand thequality of theintegrated system,as well as to eval… 相似文献
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Aiming at improving acquisition performance for direct sequence spread spectrum (DSSS) signals, a new acquisition algorithm based on fast Fourier transform (FFT ) is proposed. The code phases are parallel searched throughout the Doppler freq uency domain. Since the influence of Doppler frequency errors on peak-to-avera ge ratios of correlation power shows a pattern similar to the sinc function, it is our belief that by judging on peak-to-average ratios for different Doppler frequency errors false alarm prob... 相似文献
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针对现有相位干涉仪角度估计算法在近场条件下性能不佳的问题,该文提出一种远近场均性能良好的改进的导向矢量匹配算法。该算法采用对称结构天线接收来波信号,利用近场条件下对称位置天线的到达相位差中距离相关项对消的特性设计新的代价函数。代价函数最大值位置对应的入射角即为目标信号的入射角估计。在此基础上,利用相关函数的梯度正比于角度误差的特性设计角跟踪环路。作为一种局部极值估计算法,角跟踪环路相比其它全局最大值估计算法具有更好的相位噪声鲁棒性。仿真实验验证了该算法在不同相位噪声以及远近场条件下的优良性能。 相似文献