谐振式光学陀螺检测电路的噪声分析

噪声是限制陀螺精度的重要原因,因此为提高陀螺精度,首先要分析噪声的水平和来源。本文介绍了一种应用于谐振式光学陀螺数字检测电路的噪声逐级检测方法,并分析了检测电路中各部分的噪声源。通过对现有某陀螺检测电路进行实验数据的分析,找到了对该谐振陀螺噪声贡献最大的部分。又从信噪比角度给出确定该陀螺输入光功率的方法,计算出了它的灵敏度。实验表明此方法可以分析出陀螺检测电路中各部分的噪声源,与理论分析一致。为抑制检测电路噪声,提高陀螺精度提供依据。     

基于MUSIC的含噪声信号频率估计

频率估计是数字信号处理的重要内容,特别是对含有高斯白噪声的信号进行频率估计一直是信号处理的经典课题。频率估计不仅在理论上,而且在实际应中,都有非常重要的研究价值。本文采用空间谱估计的典型代表MUSIC算法,对含高斯白噪声的信号进行频率估计,同时也通过MATLAB软件对其进行了仿真。仿真结果表明对单、多个含噪声的正弦信号而言,MUSIC算法有良好的频率特性,并能达到预期效果。     

Alternate characterization technique for static random‐access memory static noise margin determination

The cell static noise margin (SNM) is widely used as a stability criterion for static random‐access memory cells design. This parameter is typically determined through electrical simulations since direct experimental characterization of SNM is not achievable. In this work, we present a methodology that provides an indirect measurement of the SNM on a per‐cell basis for six‐transistor SRAMs. It is based on combining an Adaptive Neuro‐Fuzzy Inference System (ANFIS) with circuit‐level cell experimentally measurable parameters as input variables to the tool. We show that it is possible to obtain the SNM for individual memory cells using the same experimental setup and data than that required for shmoo plot measurements. Results confirm that the SNM can be experimentally estimated with a relative error compared with electrical simulations that is below 0.5%. Copyright © 2012 John Wiley & Sons, Ltd.     

Automating the sizing of transistors in CMOS gates for low‐power and high‐noise margin operation

This paper presents an automatic method for sizing the transistors in CMOS gates. The method utilizes a feedback control system to efficiently optimize the transistor sizes in small and large fan‐in gates, with the primary goal of enhancing noise robustness (as characterized by the static noise margin). The gates retain their robustness under threshold‐voltage variations over a range of supply voltages. The optimized gates not only expend reduced power and energy, but also take up less area than the conventional ones. These multi‐faceted gains, however, do incur some performance loss. Copyright © 2014 John Wiley & Sons, Ltd.     

基于FPGA的调频噪声信号源的设计

介绍了雷达上噪声干扰的一种宽带调频噪声信号源的设计。主要由基带噪声产生,噪声调制数字处理和噪声调制信号输出三部分组成。其中基带噪声产生和噪声调制信号输出部分属于模拟电路,噪声调制数字处理部分是由FPGA逻辑资源实现。测试结果表明,该方案设计的调频噪声信号源满足系统现阶段的研究要求,并达到项目要求的指标。     

美军标MIL-STD-883K中噪声容限测试方法的适用性研究

提出了美军标MIL-STD-883K噪声容限测试方法在使用中的一些问题.基于对业界所用噪声容限测试方法的分析,比较了各种方法间的区别和优缺点,分析了美军标中噪声容限测试方法很少修订却长期存在的原因.通过对相关标准和测试方法的梳理,明确了美军标及其他噪声容限测试方法的适用范围,提出了我国相应标准制修订方向的建议.测试结果表明,最大乘积法和动态最大等边法在较大的范围内都适用,可以在我国相应标准中加以采用.     

云测试网络中数字噪声探头技术研究

云噪声测试网络可检测区域声音污染形态,将噪声值和噪声分布等信息发送至云服务器等处,协助有关部门实现噪声信息化监测。网络的底层,即物理层为噪声监测数字探头,是关键技术之一。文章详细描述了基于DSP 5509数字声级计技术,选用IIR数字滤波器实现噪声的A计权和C计权滤波,嵌入Zigbee无线通讯接口实现信息互联。实验表明,该数字声级计探头能够实时采集监测20 Hz~20 k Hz频域范围、40 d B~100 d B幅值动态范围的噪声信号,误差可控制在±1 d B范围之内。     

Reducing correlated noise in digital hearing aids

The intelligibility of speech in communication systems is generally reduced by interfering noise. This interference, which can take the form of environmental noise, reverberation, competing speech, or electronic channel noise, reduces intelligibility by masking the signal of interest. The reduction in intelligibility is particularly troublesome for listeners with hearing impairments, who have greater difficulty understanding speech in the presence of noise than do normal-hearing listeners. Numerous digital signal processing (DSP)-based speech enhancement systems have been proposed to improve intelligibility in the presence of noise. Several of these systems have difficulty distinguishing between noise and consonants, and consequently attenuate both. Other methods, which use imprecise estimates of the noise, create audible artifacts that further mask consonants. The objective of the present study is to develop a new noise-reduction method that can reduce additive noise without impairing intelligibility. The new method could be used to improve intelligibility in a wide variety of applications, with special attention given to digital hearing aids and other portable communication systems (e.g., cellular telephones). Here, the authors present a new wavelet-based method for reducing correlated noise in noisy speech signals. The authors provide background information on the intelligibility problem and on previous attempts to address it. A theoretical framework is then proposed for reduction of correlated noise, along with some preliminary experimental results     

数字量输入式合并单元的白噪声处理

为了提高数字化采样的可靠性及精确度,白噪声问题一直是工业界和学术界的研究热点。首先,结合智能变电站的应用实例,给出了电子式互感器的输出波形,并对白噪声分量进行频谱分析。进而,考虑滤波效果、算法稳定性、延时时间等因素,设计了相应的数字滤波器,并给出了滤波参数及处理结果。最后,结合非周期分量衰减时间常数、最大峰值瞬时误差等指标,分析和评估了滤波算法对暂态性能的影响。分析结果表明,数字滤波算法可以使白噪声削弱一半以上,且不会影响暂态性能。     

The design of low noise digital filters with controlled dynamic range

A novel digital filter structure, that allows proper positioning of the zeros of the noise transfer functions to reduce the output roundoff noise, is introduced. Relations between zero locations, roundoff noise and dynamic range are derived and are then utilized in an heuristic optimization method for synthesizing a low noise scaled digital filter structure. Illustrative examples supporting the proposed approach are included.     

Noise margin criteria for digital logic circuits

Techniques for evaluating the noise margin for families of digital logic circuits are discussed and evaluated. It is shown that the technique of evaluating the -1 slope points on the inverter transfer function as used in most modern textbooks is not a valid and reliable approach to evaluating noise margin values. It is argued that the most reliable and reasonable criterion is to maximize the product of the two noise margins. This is equivalent to maximizing the area of a rectangle embedded within the loop formed by the transfer curves of an inverter pair. Most of the material presented can be found in the early literature on noise margin. However, because of the widespread use of the -1 slope criterion in modern textbooks, it is believed that a reexamination of basic approaches to noise margins is in order     

锁相环相位噪声的研究与仿真

锁相环在数字电路中一个重要的应用就是作为频率合成器产生高性能的时钟。本文介绍了锁相环的工作原理,重点研究了锁相环输出时钟的相位噪声的影响因素。通过对其线性环路模型进行频域分析,运用反馈控制理论,讨论了环路内各器件的噪声对其输出信号相位噪声的影响。得到了锁相环能良好改善环路带内噪声的分析结果,并且利用ADS搭建仿真电路,验证分析结果,为今后高性能频率合成器的设计和应用提供参考依据。     

Digital generator of corona noise on power line carrier channels

A procedure is presented for the design of a digital simulator which generates a random time sequence having the statistical characteristics of the corona noise that occurs on transmission line carrier channels. The method involves the synthesis of an autoregressive filter excited by a white-noise generator is a part of the overall digital transmission system, which includes the generating and receiving sections, and the PLC (power line carrier) channel. The proposed procedure is applied to simulate corona noise on practical HVAC transmission lines     

Recursive digital filters with low roundoff noise

A novel method is introduced for designing recursive digital filters with very low roundoff noise. The proposed method is based on reducing the magnitudes of the noise transfer functions on the unit circle by ensuring the presence of zeros, while simultaneously synthetizing the prescribed transfer function. The final structure, which exhibits steady-state roundoff noise with low variance, is simple and economical, and canonic with respect to delay elements, although not always canonical with respect to multipliers. An illustrative example is included. The realization method is also shown to reduce the multiplier coefficient sensitivities.     

Rejection of narrow-band noise and repetitive pulses in on-site PDmeasurements

This paper deals with the possibilities of noise suppression in partial discharge (PD) measurements under on-site conditions. After the presentation of previous work, a new concept of designing a digital FIR filter with a fixed order to suppress narrow-band disturbances is presented. The method is compared to a design using adaptive filters. A filter device, which was developed as an extension for a conventional PD detector, is presented. In the second part of the paper, a method for suppressing pulse shaped noise synchronous to the test voltage is discussed. The disturbing pulses are detected automatically in a PD signal by comparing several recorded cycles of the test voltage. There are two possibilities to suppress the pulses. The first one is an off-line method that allows attenuation degrees up to 30 dB, the second one works on line, and can process continuous PD signals. For the latter case a suppression of 14 dB for worst case pulses is possible with the developed hardware. In order to demonstrate the abilities of the filters, several measurements are shown     

A simple low-cost laboratory hardware for noise generation

Circuit hardware for custom noise generation is presented, described, and explained. Its very low circuit complexity, along with the spectral and statistical features of the noise signal obtained, make it specially suitable for student use in laboratory sessions related to digital and analog communications systems     

Roundoff noise properties of second-order digital notch filters

With regard to their roundoff noise properties, canonical second-order recursive digital notch filters, with zeros on the unit circle and poles near them, are shown to fall in three distinct groups depending upon the zeros of their noise transfer functions (NTF's). One of the groups, having all-pole NTF'S, shows large noise magnitudes but the noise behaviour is well defined. The second group shows low noise magnitudes that heavily depend upon the location of the zeros of their NTF's; these zeros are related to the transfer function coefficients in a particularly simple manner. When this dependence gets complicated, as for the third group, the noise properties are ill behaved.     

无线电骚扰的统计测量方法研究

提出了一种估测数字通信系统误码率的新方法--概率信噪比评估法,该方法基于无线电噪声和电磁骚扰的统计测量.无线电噪声和电磁骚扰的统计测量方法是当前国际上研究的热点问题,通过统计测量结果可以评估噪声环境对数字通信系统的影响.给出了无线电噪声和电磁干扰统计测量所依据的理论基础和实验测试结果,建立了干扰的幅度概率分布(APD)统计模型.通过实验数据说明了干扰的统计测量特性与数字通信系统性能之间的关系.     

一种AGC控制的低噪声水声接收机

在深水隔水管监测系统上,为了接收水下节点发射的信号,研究设计了一款低噪声低功耗水下接收机。在海洋环境下,由于发射机发射功率,传播损失以及传播过程中噪声干扰等影响,造成接收信号畸变、衰减、动态范围增大等问题,不利于后端数字处理。本系统选择低噪声芯片,优化电路结构、降低系统噪声,通过六阶椭圆滤波器,选择所需频带信号通过,采用AGC实现大动态范围的压缩。海试结果显示,该系统具有高灵敏度、低噪声、低功耗、接收动态范围大等优点。     

磁悬浮陀螺转子信号的局部均值分解降噪研究

磁悬浮陀螺转子电流信号对环境变化高度敏感,信号采样过程中不可避免会引入噪声,针对该问题提出一种基于局部均值分解（local mean decomposition, LMD）,融合豪斯多夫（Hausdorff）距离与阈值降噪（threshold denoising, TD）的算法以减弱噪声干扰。首先对原始信号进行局部均值分解,得到若干乘积函数（PF）分量和一个余量,然后根据各PF分量与原始信号间的豪斯多夫距离判定噪声、信号分量,再对噪声分量进行阈值处理,最后将阈值处理后的噪声分量、信号分量及余量进行叠加得到重构信号,实现陀螺仪转子电流信号的降噪。仿真实验结果表明,重构信号的信噪比相对于原始信号平均提高了12.86 db,均方根误差平均降低了9.25×10^-6 A;实测信号降噪结果表明,该降噪算法对四条导线边的滤波增益分别为40.0%、93.5%、30.8%和50.0%。