共查询到17条相似文献,搜索用时 171 毫秒
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嵌入式自动变模控制的快速全数字锁相环 总被引:1,自引:0,他引:1
对如何提高嵌入式全数字锁相环的锁定速度进行了研究。应用MATLAB分析了影响锁相环快速锁定的主要因素。提出了一种具有高精度自动变模控制的快速全数字锁相环。它能够根据量化相位误差的大小,自动调节数字环路滤波器的模值,避免了环路在捕捉过程中出现连续的同向相位调整,减少了因相位超调所产生的振荡,从而提高了控制精度,进一步加快了锁定速度。经计算机仿真和硬件试验证实,该锁相环既可大大缩短捕捉时间,又能够大幅减少噪声对环路的干扰。 相似文献
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在通信领域中,频率合成器起着越来越重要的角色,它可以为不同标准的无线收发机提供可编程低噪声的稳定本振信号,其性能可决定整个无线收发系统的性能。本文即是对应用于无线数字通信领域的锁相环式频率合成器系统级设计的研究。本论文结合相关文献,总结出了一套基于ADS-PLL Design Guide软件的可适用于锁相环式频率合成器的系统级设计方法。在所要求的L波段频率范围内(29042984MHz),该设计方法可以快速有效的实现频率合成器的锁定设计,仿真结果显示,对于整个所需频率范围内,采用优化后的二阶环路无源滤波器,环路均能锁定频率输出,锁定时间小于250μs。 相似文献
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提出基于坐标变换理论的新型数字锁相环,用以在三相电网电压出现频率偏移时,快速跟踪系统频率的变化,实现锁相功能.建立基于新型数字锁相环的三相电压型PWM整流器模型,分析了所提出的锁相环的电路结构和工作原理.通过仿真验证,新型数字锁相环能够准确快速锁定系统相位,PWM整流器可实现单位功率因数运行. 相似文献
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智能模值控制的数字锁相环的FPGA设计与分析 总被引:1,自引:1,他引:0
锁相环器件的数字集成化,使得全数字锁相环在数字通信中得到了极为广泛的应用;传统的K模计数器构成的数字锁相环虽然实现简单,但无法同时顾及到环路锁定时间和相位抖动噪声,因此设计了一种基于FPGA的智能控制K模计数器模值的数字锁相环;该设计能够在环路工作的不同阶段自动调整K模计数器的模值大小,从而实现了在缩短环路锁定时间的同时减小相位噪声误差;实际应用结果表明,该设计在低频段的频率跟踪应用中,系统的捕获时间有明显的缩短,相位抖动噪声也得到良好的控制。 相似文献
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介绍了一种应用VHDL语言设计数字锁相环的设计方法,阐明其基本工作原理和设计思想,给出了系统主要模块的设计过程和仿真结果;用可编程逻辑器件FPGA予以实现。该方案提高了DPLL的快速锁定性能,同时保证了锁定精度。 相似文献
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提出一种基于锁相环技术的无位置传感器控制策略,该控制策略将系统输出的相位与给定信号相位的相位差值锁定为一个固定值,根据锁相环特性就可以得出电机位置、频率信号。仿真结果表明,该方法实现了全速范围内转子位置、速度的准确、快速检测。 相似文献
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数字锁相环的优化设计与应用 总被引:3,自引:3,他引:0
胡永红 《计算机测量与控制》2006,14(8):1085-1086,1092
为了提高数字锁相环的工作频率、改善环路性能,提出了提高环路的优化设计方法,给出了数字锁相环(DPLL)的工作原理,通过对数字锁相环电路的设计分析,详细论述了利用数字微分将锁相环的鉴相器和环路滤波器完全数字化的电路设计方法,仿真结果表明:环路的工作频率由原来的几百kHz提高到几MHz,目前该数字锁相环已成功地应用于某测控系统中,应用结果证实:该数字锁相环具有工作频率高、捕获时间及精度可调、接口简单、通用性好等特点,可推广应用于远程测量与控制系统中. 相似文献
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The techniques for making decisions, that is, branching, play a central role in complete methods for solving structured instances
of constraint satisfaction problems (CSPs). In this work we consider branching heuristics in the context of propositional
satisfiability (SAT), where CSPs are expressed as propositional formulas. In practice, there are cases when SAT solvers based
on the Davis-Putnam-Logemann-Loveland procedure (DPLL) benefit from limiting the set of variables the solver is allowed to
branch on to so called input variables which provide a strong unit propagation backdoor set to any SAT instance. Theoretically,
however, restricting branching to input variables implies a super-polynomial increase in the length of the optimal proofs
for DPLL (without clause learning), and thus input-restricted DPLL cannot polynomially simulate DPLL. In this paper we settle
the case of DPLL with clause learning. Surprisingly, even with unlimited restarts, input-restricted clause learning DPLL cannot
simulate DPLL (even without clause learning). The opposite also holds, and hence DPLL and input-restricted clause learning
DPLL are polynomially incomparable. Additionally, we analyze the effect of input-restricted branching on clause learning solvers
in practice with various structured real-world benchmarks.
This is an extended version of a paper [27] presented at the 13th International Conference on Principles and Practice of Constraint Programming (CP 2007) in Providence,
RI, USA. The first author gratefully acknowledges financial support from Helsinki Graduate School in Computer Science and
Engineering, Academy of Finland (grants #211025 and #122399), Emil Aaltonen Foundation, Jenny and Antti Wihuri Foundation,
Finnish Foundation for Technology Promotion TES, and Nokia Foundation. The second author gratefully acknowledges the financial
support from Academy of Finland (grant #112016). 相似文献
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提出了一种新的用于实现SDH设备时钟的数字锁相环,采用时数转换器来实现数字锁相环中的鉴相器;该时数转换器的时间测量精度达到200 ps,因而极大地改进了鉴相器的鉴相精度;改进后的数字锁相环具有很好的频率稳定度和相位特性,对时钟源有很好的跟踪能力,且能实现时钟源的平滑切换,完全满足了ITU-T G.813规范要求。 相似文献
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In digital communication systems, typical methodologies in determining loop parameters of the digital phase-locked loop (DPLL) are based on the mapping transformation from the analog domain to the digital domain. However, such transform based algorithms are relatively complicated and not straightforward, and they also cause the problem that loop parameters are affected by the pre-detection integration time greatly. To solve these issues, an effective direct method of determining loop parameters of the second-order DPLL in the z-domain is proposed in this paper. Through ascertaining specific positions of the closed-loop system function's poles inside the right-hand side of the z-plane's unit circle, unknown parameters are calculated directly and flexibly in this method, which enables the DPLL to acquire good low-pass filtering characteristic and system stability. This novel method not only reduces the complexity of solving the parameters, but also eliminates the effect of the pre-detection integration time on loop parameters. Simulation results are provided to confirm the feasibility of the proposed method and to show that the DPLL obtained by this method achieves the similar tracking performance to the discretized PLL. 相似文献