An intuitive error analysis for FDTD and comparison to MoM

The accuracy of the Finite-Difference Time-Domain (FDTD) algorithm is commonly treated in two ways: a local analysis of the error in a finite-difference stencil, and the numerical dispersion relation for plane-wave propagation. This article presents a simple solution error estimate that connects these two approaches. This error estimate is nearly identical to a solution error estimate for the Method of Moments, except that the FDTD error includes an additional dependence on the electrical problem size.     

An accurate error analysis model for fast Fourier transform

An error propagation model is proposed for the in-place decimation-in-time version of the radix-2 FFT algorithm. With the model, an accurate error expression and error variance for the computation of FFT are derived. This correspondence deals with fixed-point and block floating-point arithmetic. Simulation results agree closely with the theoretical predicted ones. We find that some roundoff errors at different stages correlate with each other. The density of correlations is closely associated with the round-off approach used in butterfly calculations     

Node-to-node error sensitivity analysis using a graph based approach for VLSI logic circuits

Shrinking the transistors size and supply voltage in the advanced VLSI logic circuits, significantly increases the susceptibility of the circuits to soft errors. Therefore, analysis of the effects on other nodes, caused by the soft errors occurring at each individual node is an essential step for VLSI logic circuit design. In this paper, a novel approach based on the Mason’s gain formula, for the node-to-node sensitivity analysis of logic circuits is proposed. Taking advantage of matrix sparsity, the runtime and the memory requirement of the proposed approach become scalable. Also, taking the effects of reconvergent paths into account, the accuracy of the proposed approach is improved considerably. According to the simulation results, the proposed approach runs 4.7× faster than those proposed in the prior works while its computational complexity is O(N^1.07) on the average.     

An efficient algorithm for sensitivity analysis of nonuniform transmission lines

This paper presents a new algorithm that addresses an important issue arising in computation of sensitivity for nonuniform transmission lines using the idea of model reduction through integrated congruence transform. This issue is related extending the concept of implicit basis construction, which was introduced earlier to simulate nonuniform transmission lines, to the task of sensitivity analysis. A new algorithm is presented to compute the orthogonal basis needed to obtain the reduced system used in sensitivity analysis. The proposed algorithm incorporates a new orthogonalization procedure which can be used to find an orthogonal basis for a set of moments derived from inhomogeneous differential equations, but without having to compute those moments explicitly. Numerical results demonstrate that reduced-order systems constructed by the proposed algorithm have improved numerical accuracy in sensitivity computation.     

An analysis of the block error probability performance of iterative decoding

Asymptotic iterative decoding performance is analyzed for several classes of iteratively decodable codes when the block length of the codes N and the number of iterations I go to infinity. Three classes of codes are considered. These are Gallager's regular low-density parity-check (LDPC) codes, Tanner's generalized LDPC (GLDPC) codes, and the turbo codes due to Berrou et al. It is proved that there exist codes in these classes and iterative decoding algorithms for these codes for which not only the bit error probability P/sub b/, but also the block (frame) error probability P/sub B/, goes to zero as N and I go to infinity.     

转轴转角定位误差测量方法与误差分析

提出了一种基于光纤激光自准直转轴转角定位误差测量的方法,建立了包含转轴运动误差以及安装误差的误差模型,仿真分析了23项误差对转角定位误差测量的影响,结果表明仅有参考转轴与待测转轴之间的4项安装误差的影响量与转轴旋转角度相关,且只需精细调整其中两项角度安装误差即可保证影响量小于0.2。利用所搭建的测量装置对某分度盘的转角定位误差进行了测量,三次测量重复性偏差约为0.9,与光电自准直仪对比的最大偏差约为0.6。结果表明:利用该测量方法和测量装置可以实现转轴转角定位误差的全周范围高精度测量,验证了所提出模型的有效性。     

Compression and error sensitivity of two-dimensional facsimile coding techniques

Seven proposals were submitted to the International Telegraph and Telephone Consultative Committee (CCITT) for selection of a standard two-dimensional code as an extension of the current CCITT standard one-dimensional code. The CCITT specified the use of particular parameters and procedures to compare the candidate techniques on a quantitative basis. The compression ratio and error sensitivity of all seven coding techniques were measured for a wide range of operational conditions. For example, tests are performed with small K-factors for application to error-prone transmission over switched circuits, and also at infinite K-factor to simulate packet switching networks possessing error control. Particular attention is paid to the error detection/correction procedure to insure that the error sensitivity parameter is as realistic as possible. The essential differences between the seven proposed coding techniques are presented, and the measurement parameters and procedures are reviewed.     

短波慢跳频系统误码率分析

本文分析了在慢跳频系统中由于多径效应引起的误码率，并推导了经过自适应均衡后的误码率。模拟分析结果表明：基于平方根卡尔曼算法的判决反馈均衡器的引入大大降低了误码率。     

遥测试验数据误码统计分析

遥测数据误码直接影响飞行试验数据结果的分析和评估,建立合适的误码率模型对遥测数据处理的质量起着关键作用。本文在Rice衰落模型以及信号强度测距模型基础上对飞行试验多站数据进行分析,估计出接收端误码分布情况,得到了误码分布模型。从统计结果看出,遥测数据帧内误码分布为独立同分布,与位置无关,而帧间误码随飞行器与接收天线之间的距离减小而减少。多站数据误码分布的讨论为多站数据融合提供理论支持。     

Noise sensitivity of sparse signal representations: reconstruction error bounds for the inverse problem

Certain sparse signal reconstruction problems have been shown to have unique solutions when the signal is known to have an exact sparse representation. This result is extended to provide bounds on the reconstruction error when the signal has been corrupted by noise or is not exactly sparse for some other reason. Uniqueness is found to be extremely unstable for a number of common dictionaries.     

An analysis of error inducing parameters in multihop sensor node localization

Ad hoc localization of wireless sensor nodes is a fundamental problem in wireless sensor networks. Despite the recent proposals for the development of ad hoc localization algorithms, the fundamental behavior in systems using measurements has not been characterized. In this paper, we take a first step toward such a characterization by examining the behavior of error inducing parameters in multihop localization systems in an algorithm independent manner. We first derive the Crame Rao Bound for Gaussian measurement error for multihop localization systems using distance and angular measurements. Later on, we use these bounds on a carefully controlled set of scenarios to study the trends in the error induced by the measurement technology accuracy, network density, beacon node concentration, and beacon uncertainty. By exposing these trends, the goal of this paper is to develop a fundamental understanding of the error behavior that can provide a set of guidelines to be considered during the design and deployment of multihop localization systems.     

An automatic phase error compensating multiphase LC oscillator: analysis and design

In this work a self phase error compensating multiphase LC oscillator is proposed. Mismatches in LC tanks are considered as the main source of phase errors. Considering this, an analytical approach is proposed to find a relationship between phase errors and their corresponding coupling factors as a necessary condition for phase error cancellation then a self compensating circuit is proposed accordingly. The compensation circuit first detects the phase errors then employs them in a current tuner to change each stage coupling factor to reduce phase errors. The building blocks of the proposed circuit are investigated and the transistor level implementation of each one is presented afterwards. The theoretical results are evaluated and confirmed through simulations using ADS software in 0.18 μm CMOS technology. Simulation results show that not only phase errors are reduced with respect to the previous methods but also this procedure does not impose any further power consumption and phase noise to the circuit.     

An error probability analysis of the optimum noncoherent multiuser detector for multipath and multiantenna diversity communications over Rayleigh-fading channels

The optimum noncoherent multiuser detector is obtained for generalized diversity symbol-synchronous communication systems that employ nonorthogonal multipulse modulation. A unified approach is adopted to simultaneously address various forms of diversity such as time, frequency, multipath, and/or receiver-amenna diversity. Upper and lower bounds on the average bit-error probability of the optimum noncoherent detector are derived. While these bounds are numerically computable, they are too complicated to give insights about the relative influence of system parameters on the essential behavior of the bit-error rate. To address this issue, an asymptotic (low noise) analysis of the bit-error probability is undertaken. It is shown that the upper and lower bounds are indeed asymptotically convergent. A formula for the asymptotic efficiency of the optimum noncoherent detector is thereby derived. Interestingly, the asymptotic efficiency is found to be positive, and independent of the signal strengths of the interfering users.     

An application-oriented error control scheme for high-speednetworks

Many new network applications demand interprocess communication (IPC) services that are not supported by existing transport protocol mechanisms. Large bandwidth-delay products of high-speed networks also render some of the existing error and flow control mechanisms less efficient. In particular, new error control schemes that can provide variable degrees of error recovery according to the application's requirements are desirable. This paper presents the design, evaluation, and implementation of an application-oriented error control-scheme that is aimed at supporting efficient IPC in high-speed networking environments. Our results indicate that the proposed error control scheme allows effective control of the trade-off between the amount of error an application can tolerate and the amount of delay it has to suffer     

An error correcting scheme for defective memory

A scheme for storing information in a memory system with defective memory ceils using "additive" codes was proposed by Kuznetsov and Tsybakov. When a source message is to be stored in a memory with defective cells, a code vectorxmasking the defect pattern of the memory is formed by adding a vector defined by the message and the defect pattern to the encoded message, and thenxis stored. The decoding process does not require the defect information. Considerably better bounds on the information rate of codes of this type which are capable of masking multiple defects and correcting multiple temporary errors are presented. The difference between the upper and lower bounds approaches the difference between the known best upper and lower bounds for random error correcting linear codes as the word length becomes large. Examples of efficient codes for masking double or fewer defects and correcting multiple temporary errors are presented.     

一种高效数字滤波器结构及其灵敏度分析

本文基于矩阵分解,提出了一种新的数字滤波器结构,并导出了其传递函数的灵敏度表达式。该结构实际上是文献[10]中提出结构的改进型,比后者更加简单,易于实现。同时,本文对此结构同传统的几个主要结构进行了性能上的比较。仿真结果表明,同经典最佳结构相比,新结构抵抗有限字长误差的能力与其非常接近,但由于结构的简洁性,新结构在实时信号处理中具有更大的实用价值。     

Stability and error analysis of the LED-logarithmic electrometer

Theoretical analysis of the stability and error in the LED-logarithmic electrometer is presented. It has been shown that a resistance in series with the log element improves the response by a factor of 7 at 1pA. Error analysis of the electrometer, involving mainly device parameter sensitivity, is also presented. It has been found that variation in temperature and change in value of the device constant are more important factors than other device parameters in influencing the variation in the output voltage. An eight-decade temperature compensated LED-logarithmic electrometer is designed for the measurement of low currents from 1pA to 0.1mA and has been tested for its performance in the temperature range of –20 to 70°C.     

Combined error concealment and error correction in rate-distortion analysis for multiple substream transmissions.

We propose a new framework for multiple scalable bitstream video communications over lossy channels. The major feature of the framework is that the encoder estimates the effects of postprocessing concealment and includes those effects in the rate-distortion analysis. Based on the framework, we develop a rate-distortion optimization algorithm to generate multiple scalable bitstreams. The algorithm maximizes the expected peak signal-to-noise ratio by optimally assigning forward error control codes and transmission schemes in a constrained bandwidth. The framework is a general approach motivated by previous methods that perform concealment in the decoder, as in our special case. Simulations show that the proposed approach can be implemented efficiently and that it outperforms previous methods by more than 2 dB.     

基于恒模直线阵的系统敏感性研究

以恒模直线阵为对象，研究了智能天线系统存在瞄准误差、阵元位置误差、阵元失效等误差情况下对恒模直线阵干扰抑制能力等系统性能的影响。仿真结果表明，瞄准方向误差和阵元失效对恒模直线阵的影响较小，而对阵元位置误差敏感性稍高。但与传统的波束形成器相比，恒模直线阵中信号恢复对阵列结构的非理想性并不敏感。为进一步研究智能天线的实用化与鲁棒自适应算法提供了基础。     

Fundamentals of error analysis

This paper discusses the process of assessing the uncertainty of measurement results through error analysis. We restrict the discussion to sources of errors, measurement errors, modeling errors, and calibration errors in the context of physical experiments.