共查询到19条相似文献,搜索用时 203 毫秒
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针对船舶动力机械装置未知时变窄带噪声的有源控制问题,基于锁相环信号跟踪生成原理,通过在锁相环中引入次级通道执行机构,推导了新的未知时变窄带噪声有源控制方法.首先,通过EPLL(Enhanced Phase Locked Loop)环节中引入次级通道,形成基于EPLL的未知时变窄带噪声有源控制方法;其次,通过近似分析得到其等效线性差分方程,研究了窄带噪声信号幅值和次级通道特性对算法收敛性能的影响;再次,通过引入幅值归一化和次级通道归一化改进措施,提出了基于Pseudolinear(PL)-EPLL的窄带噪声控制方法.相比原方法,改进算法幅值、频率/相位收敛方程的收敛特性与窄带噪声信号幅值和次级通道特性无关,对不同强度分量的多频窄带噪声控制,具有较为一致的收敛速度.最后,通过仿真分析,验证所提出方法的有效性. 相似文献
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在免提电话和视频会议系统中,自适应滤波器估计的回声路径通常是稀疏的.改进的比例归一化最小均方(IPNLMS)算法能够加快自适应滤波器在估计稀疏系统时的收敛速度,但与归一化最小均方(NLMS)算法相比,其稳态失调的波动性较大.为了解决这一问题,本文提出了一种时变参数IPNLMS(TV-IPNLMS)算法.该算法根据系统的均方误差(MSE)与噪声功率的比值,使用一个sigmoid函数来调整时变参数的值.该时变参数能够降低IPNLMS算法在滤波器到达稳态时的比例增益.仿真结果表明,时变参数方法能够降低IPNLMS算法稳态失调的波动性.该算法可用于回声消除、主动噪声控制等领域. 相似文献
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针对冲击噪声背景下,常规波束形成算法性能下降的问题,本文提出一种适用于任意未知统计特性的代数拖尾冲击噪声环境下的基于归一化的线性约束特征干扰相消器(N-LCEC)算法。该算法在附加线性约束的条件下,以噪声功率最小化为目标函数;通过对输入信号进行无穷范数归一化,使变换信号的二阶统计量在代数拖尾的冲击噪声环境下存在且有界,然后将自适应权矢量约束于噪声子空间的方法,提高了波束形成器在冲击噪声背景下的性能。N-LCEC算法无需噪声特征指数的先验信息,适用冲击噪声环境更广;N-LCEC算法具有运算简单,干扰抑制能力强,同时保持静态方向图的副瓣特征等优点。仿真结果验证了该算法的有效性和优越性。 相似文献
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为了有效解决主动降噪耳机系统的低频噪声,采用变步长FXLMS自适应滤波算法,克服传统定步长收敛速度与稳态误差相互制约的不足,通过构造合适的变步长因子,不但改善算法的收敛速度,而且减少了稳态误差.构建主动降噪耳机模拟控制系统,模拟次级通道路径,对噪声进行处理,仿真实验表明,该算法可以有效降低频噪声,相较于传统算法,该算法具有较好的性能. 相似文献
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目标跟踪系统的数学模型或统计特性的不确定性,往往会导致机动目标跟踪精度降低甚至跟踪发散。在综合平方根求容积卡尔曼滤波算法和改进的Sage-Husa估计器的基础上,提出一种自适应求容积平方根卡尔曼滤波算法。该算法通过实时估计未知系统噪声,抑制由于噪声统计特性未知时变而导致的滤波误差,从而实现机动目标的自适应跟踪。仿真结果表明,在系统噪声未知时变,且与先验系统噪声存在一定差异时,自适应平方根求容积卡尔曼滤波器能有效地改进标准平方根求容积卡尔曼滤波器的跟踪精度和跟踪稳定性。 相似文献
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This paper presents a low phase noise and low reference spur quadrature phase-locked loop(QPLL) circuit that is implemented as a part of a frequency synthesizer for China UWB standard systems.A glitch-suppressed charge pump(CP) is employed for reference spur reduction.By forcing the phase frequency detector and CP to operate in a linear region of its transfer function,the linearity of the QPLL is further improved.With the proposed series-quadrature voltage-controlled oscillator,the phase accuracy of the QPLL is guaranteed.The circuit is fabricated in the TSMC 0.13μm CMOS process and operated at 1.2-V supply voltage.The QPLL measures a phase noise of -95 dBc/Hz at 100-kHz offset and a reference spur of -71 dBc.The fully-integrated QPLL dissipates a current of 13 mA. 相似文献
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This paper presents an adaptive bacterial foraging optimization (ABFO) algorithm for an active noise control system. The conventional active noise control (ANC) systems often use the gradient-based filtered-X least mean square algorithms to adapt the coefficients of the adaptive controller. Hence, there is a possibility to converge to local minima. In addition, this class of algorithms needs prior identification of the secondary path. The ABFO algorithm helps the ANC system to prevent falling into local minima. The proposed ANC system is also simpler since it does not need any prior information of the secondary path. Moreover, the adaptive strategy of the algorithm results in improved search performance compared with the basic bacterial foraging optimization algorithm, as well as other conventional algorithms. Experimental studies are performed for nonlinear primary path along with linear and nonlinear secondary path. The results show the effectiveness of the proposed ABFO-based ANC system for different kinds of input noise. 相似文献
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This paper presents a Volterra filtered-X least mean square (LMS) algorithm for feedforward active noise control. The research has demonstrated that linear active noise control (ANC) systems can be successfully applied to reduce the broadband noise and narrowband noise, specifically, such linear ANC systems are very efficient in reduction of low-frequency noise. However, in some situations, the noise that comes from a dynamic system may he a nonlinear and deterministic noise process rather than a stochastic, white, or tonal noise process, and the primary noise at the canceling point may exhibit nonlinear distortion. Furthermore, the secondary path estimate in the ANC system, which denotes the transfer function between the secondary source (secondary speaker) and the error microphone, may have nonminimum phase, and hence, the causality constraint is violated. If such situations exist, the linear ANC system will suffer performance degradation. An implementation of a Volterra filtered-X LMS (VFXLMS) algorithm based on a multichannel structure is described for feedforward active noise control. Numerical simulation results show that the developed algorithm achieves performance improvement over the standard filtered-X LMS algorithm for the following two situations: (1) the reference noise is a nonlinear noise process, and at the same time, the secondary path estimate is of nonminimum phase; (2) the primary path exhibits the nonlinear behavior. In addition, the developed VFXLMS algorithm can also be employed as an alternative in the case where the standard filtered-X LMS algorithm does not perform well 相似文献
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传统的线性主动噪声控制算法在噪声信号或噪声通道呈现非线性特性的情况下控制效果不佳。核-滤波最小均方误差算法(Kernel Filtered x Least Mean Square,KFxLMS)通过将输入噪声信号映射到高维再生核希尔伯特空间,再用线性方法在高维空间中进行处理。然而,随着新噪声信号的输入,KFxLMS算法递增的核函数运算需要较高的成本。为进一步改进KFxLMS算法,本文提出了随机傅里叶特征核滤波最小均方误差算法(Random Fourier Feature - Kernel Filtered x Least Mean Square,RFF-KFxLMS)。在仿真实验部分讨论了算法的参数选择,给出了算法的计算耗时,并验证了提出的RFF-KFxLMS算法在非线性噪声通道情况下,针对不同频率分量的正弦噪声都能够达到理想的性能。 相似文献
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Omar Al-kharji Al-Ali Mahmoud Al-Qutayri Saleh Al-Araji 《International Journal of Electronics》2013,100(6):746-761
This article proposes a time-delay digital tanlock loop (TDTL), which uses a new phase detector (PD) design that is optimised for noise reduction making it amenable for applications that require wide lock range without sacrificing the level of noise immunity. The proposed system uses an improved phase detector design which uses two phase detectors; one PD is used to optimise the noise immunity whilst the other is used to control the acquisition time of the TDTL system. Using the modified phase detector it is possible to reduce the second- and higher-order harmonics by at least 50% compared with the conventional TDTL system. The proposed system was simulated and tested using MATLAB/Simulink using frequency step inputs and inputs corrupted with varying levels of harmonic distortion. A hardware prototype of the system was implemented using a field programmable gate array (FPGA). The practical and simulation results indicate considerable improvement in the noise performance of the proposed system over the conventional TDTL architecture. 相似文献
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自偏置锁相环电路结构自提出以来便受到了极大的关注,人们普遍认为其可以改善锁相环的相位噪声。为了验证这种结构能否改善传统锁相环电路的相位噪声性能,根据锁相环的基本理论设计并实现了一种可进行重新配置的锁相环电路结构,电路中的锁相环结构可以在传统锁相环、自偏置锁相环和普通偏置锁相环之间进行切换。使用信号源分析仪分别测试得到了这3种结构的相位噪声性能:自偏置锁相环的带内相位噪声比普通锁相环恶化了约6 dB,而采用普通偏置锁相环使环路等效分频比减小5的相位噪声比普通锁相环改善了约14 dB。理论与测试结果均表明,自偏置锁相环和普通锁相环相比,环路反馈回路中的分频比并没有有效降低,因此自偏置锁相环的相位噪声性能并没有得到改善。 相似文献