Statistical analysis of initialization methods for RLS adaptivefilters

Theoretical analysis is used to evaluate the mean and second-moment properties of recursive least squares algorithms incorporating the fast exact initialization and soft constrained initialization methods during the initialization period. It is shown that the weight vector mean and covariance produced by fast exact initialization are undefined for this period. Theoretical results are derived for soft constrained initialization that show that the weight vector mean and covariance are finite, and expressions are given for these quantities. Simulations for various cases are presented to support the accuracy of these theoretical results     

Finite-precision analysis of a covariance algorithm for leastsquares FIR filtering and AR modeling

A numerically stable, fast, order-recursive algorithm for solving the covariance problem in signal modeling is described. The propagation of finite arithmetic errors as well as data acquisition errors is studied in detail. First, linearization of the main algorithmic recursions is carried out. Then, a suitable transformation converts the resulting state equations of the accumulated errors into their residual form. Subsequently, bounds for the residuals are computed. The derivation of these bounds depends heavily on the Levinson type structure of the algorithm and the low displacement rank of the problem. The main result is that the algorithm is weakly numerically stable. The proposed order-recursive algorithm is subsequently utilized as a block adaptive method. Its performance is also demonstrated by long run simulations     

Relaxed Annihilation-Reordering Look-Ahead QRD-RLS Adaptive Filters

The optimum architecture design and mapping of QRD-RLS adaptive filters can be achieved through filter architecture selections, look-ahead transformations, and hierarchical pipelining/folding transformations. In this paper, a relaxed annihilation-reordering look-ahead (RARL) architecture is proposed, and shown to be more power and area efficient than pipelined processing architecture which was considered the most area efficient. The filters with this architecture are based on relaxed weight-update through filtering approximation, where a filter tap weight is updated upon arrival of every block of input data, and are speeded up with annihilation-reordering look-ahead transformation. As a result of the computational complexity reduction, this architecture does not change the iteration bound and filter clock frequency, and leads to speed up with linear increase in power consumption, while the pipelined processing architectures result in speedup with quadratic increase in power consumption. Upon hardware mapping, this architecture is also more advantageous to achieve low area designs. Two design examples are presented to illustrate mapping optimization using above transformations. These results are important for mapping designs onto ASICs, FPGAs or parallel computing machines. The results show significant improvements in throughput, power consumption and hardware requirement. It is also interesting to show through mathematics and simulations that the RARL QRD-RLS filters have no performance degradation in terms of convergence rate.     

稀疏自适应Volterra滤波的QRD-RLS算法

求解非线性问题时,非线性Volterra滤波的性能明显优于线性滤波;稀疏结构Voherra滤波器有效降低了Volterra滤波的工程应用复杂度;本文针对稀疏Volterra滤波,改进了基于QR分解的RLS算法,在更换滤波器抽头的时候保留了先前的数据信息,从而加速当前抽头的收敛,加快了滤波器核矢量的更新和替换.仿真结果表明改进的QRD-RKS算法具有快速自适应能力;一同验证了稀疏Volterra滤波的有效性.     

JPEG2000中小波滤波器的定点分析及其VLSI实现

对JPEG2 0 0 0中推荐的 5 /3整数滤波器和 9/7实数滤波器进行了硬件实现时所需要的有限精度分析 ;确定了小波变换过程中各个参数的最佳数据宽度 ,还确定了整个变换系统的数据通路的数据宽度。基于lifting的小波变换的特点结合嵌入式延拓算法提出了两种小波变换———折叠结构和长流水线结构 ;对两种结构进行了分析比较。最后 ,对折叠结构和相关的其它结构在所需存储单元的数量、存储单元的访问次数、处理能力以及功耗等方面进行了分析比较 ,可以看出文中提出的结构在性能上有明显优点。     

A class of adaptive step-size control algorithms for adaptivefilters

A class of new adaptive step-size control algorithms, which is applicable to most of the LMS-derived tap weight adaptation algorithms, is proposed. Analysis yields a set of difference equations for theoretically calculating the transient behavior of the filter convergence and derives an explicit formula for the steady-state excess mean-square error (EMSE). Experiments for some examples prove that the proposed algorithm is highly effective in improving the convergence rate in both transient and tracking phases. The theoretically calculated convergence is shown to be in good agreement with that obtained through simulations. Alternative formulae of the step-size adaptation for specific tap weight adaptation algorithms are also proposed     

Acoustic echo control. An application of very-high-order adaptivefilters

We have discussed the application of high-order adaptive filters to the problem of acoustical echo cancellation with particular application to hands free telephone systems. We described a means to achieve robust performance. We further presented methods for reducing computational complexity that allow implementation in low-cost, fixed-point digital signal processors. Progress in technology will allow the use of more sophisticated algorithms at lower cost in the near future     

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.     

内场干涉仪测向误差分析及相位误差校正方法

根据干涉仪测向的基本原理,分析了干涉仪测向误差产生原因,提出了近场试验条件下的相位误差校正方法,可消除试验条件对测向误差的影响,提高试验结果可信度。仿真结果说明,本文提出的内场干涉仪测向误差校正方法可显著减少内场测试的影响。     

Performance Analysis of Blind Adaptive MOE Multiuser Receivers Using Inverse QRD-RLS Algorithm

The inverse QR (IQRD) recursive least-squares (RLS) algorithm (IQRD-RLS) is very popular because it has good numerical stability and can be mapped onto COordinate Rotation DIgital Computer (CORDIC) processor-based systolic arrays, which are suitable for very large-scale integrated circuits (VLSI) architecture and real-time applications. In this paper, the blind optimal minimum output energy (MOE) detector which is developed for multiuser detection (MUD) in direct-sequence code-division multiple-access (DS-CDMA) systems is implemented using the linearly constrained IQRD-RLS algorithm. Specifically, the max/min approach is combined with subspace tracking for producing the optimal MOE multiuser detector. A new fast subspace tracking algorithm based on Lagrange multiplier methodology and the IQRD-RLS algorithm is developed. A comparative analysis among the recently emerged channel-estimation techniques is conducted using the IQRD-RLS algorithm. The corresponding robust MOE receivers at low SNR are implemented using the IQRD method, and their performances are assessed in terms of SINR, BER, and computational complexity. A robust multiuser receiver is developed by adding a quadratic inequality constraint to the optimal max/min MOE detector. The feasibility of systolic array implementation of the IQRD-based optimal MOE detector is explored. Several simulation experiments are conducted in a severe near–far environment to analyze the IQRD-based receivers and the subspace tracking algorithms.      

Adaptive linearly constrained inverse QRD-RLS beamforming algorithm for moving jammers suppression

A general, linearly constrained (LC) recursive least squares (RLS) array-beamforming algorithm, based on an inverse QR decomposition, is developed for suppressing moving jammers efficiently. In fact, by using the inverse QR decomposition-recursive least squares (QRD-RLS) algorithm approach, the least-squares (LS) weight vector can be computed without back substitution and is suitable for implementation using a systolic array to achieve fast convergence and good numerical properties. The merits of this new constrained algorithm are verified by evaluating the performance, in terms of the learning curve, to investigate the convergence property and numerical efficiency, and the output signal-to-interference-and-noise ratio. We show that our proposed algorithm outperforms the conventional linearly constrained LMS (LCLMS) algorithm, and the one using the fast linear constrained RLS algorithm and its modified version.     

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.     

不同衍射计算方法比较及误差分析

对多种衍射计算方法进行了比较及误差分析,为衍射计算方法的合理选择提供了指导.研究表明衍射距离小于波长的情况下,经典标量衍射或矢量衍射都有较大误差,需要使用电磁场仿真软件进行计算;波长量级下矢量衍射模型较为准确;一般距离下,矢量衍射与标量衍射计算结果几乎一致.标量衍射模型中积分法和角谱法计算结果的差距随着衍射距离的增加逐...     

运动视觉误差分析的模型设计与实现

针对运动目标模型三维建模中,视觉误差导致建模的准确性不好的问题,提出一种基于运动视觉误差补偿的三维模型设计方法。采用全息投影方法进行三维运动模型图形采集,结合边缘像素特征提取方法进行三维模型的体绘制,根据运动视觉误差补偿方法构建图像重构的三维数据场,进行运动模型的边缘轮廓特征提取和Harris角点检测,实现运动模型的三维重建和视景仿真重构。仿真结果表明,采用该方法进行运动模型重建,输出三维模型的噪点较小,轮廓特征配准精度较高,运动图像识别的视觉误差收敛到零,提高成像质量。     

Multiple error detection and identification via signature analysis

Signature analysis has been used widely for fault detection as a part of Built-In Self Test (BIST). In this paper we show how signature analysis can be used not only for fault detection but also for identification of multiple errors produced by faults in the circuits under test. We construct Signature Analysis Registers (SARs) to detect and identify any specified number of errors in the input polynomials by choosing proper characteristic polynomials. To detect and identifyr errors in an input bit stream ofm bits, we use a polynomialg _r (x)=1cm (f ₁ (x), f ₃ (x), ..., f _2r?1 (x)) as the characteristic polynomial for the SAR for any polynomialf ₁ (x), where lcm represents the least common multiple of polynomials al $$fi(x) = Res_t (f_1 (t),x - t^i ), i = 3,...,2r - 1,$$ Res _t denotes thet-Resultant, andm is less than the order off ₁ (x). Given a faulty signature produced by an SAR constructed as described, we present an algorithm for the identification of the actual error bits in the input polynomial to the SAR. We also extend the use of BCH codes for error detection and correction to include nonprimitive polynomials.     

Stability and phase error analysis of FD-TD in dispersivedielectrics

Four FD-TD extensions for the modeling of pulse propagation in Debye or Lorentz dispersive media are analyzed through studying the stability and phase error properties of the coupled difference equations corresponding to Maxwell's equations and to the equations for the dispersion. For good overall accuracy the author shows that all schemes should be run at their Courant stability limit, and that the timestep should finely resolve the medium timescales. Particularly, for Debye schemes it should be at least Δt=10^-3τ, while for Lorentz schemes it should be Δt=10^-2τ, where τ is a typical medium relaxation time. A numerical experiment with a Debye medium confirms this. The author has determined that two of the discretizations for Debye media are totally equivalent. In the Lorentz medium case the author establishes that the method that uses the polarization differential equation to model dispersion is stable for all wavenumbers, and that the method using the local-in-time constitutive relation is weakly unstable for modes with wavenumber k such that kΔx>π/2     

Design and analysis of vector color error diffusion halftoningsystems

Traditional error diffusion halftoning is a high quality method for producing binary images from digital grayscale images. Error diffusion shapes the quantization noise power into the high frequency regions where the human eye is the least sensitive. Error diffusion may be extended to color images by using error filters with matrix-valued coefficients to take into account the correlation among color planes. For vector color error diffusion, we propose three contributions. First, we analyze vector color error diffusion based on a new matrix gain model for the quantizer, which linearizes vector error diffusion. The model predicts the key characteristics of color error diffusion, esp. image sharpening and noise shaping. The proposed model includes linear gain models for the quantizer by Ardalan and Paulos (1987) and by Kite et al. (1997) as special cases. Second, based on our model, we optimize the noise shaping behavior of color error diffusion by designing error filters that are optimum with respect to any given linear spatially-invariant model of the human visual system. Our approach allows the error filter to have matrix-valued coefficients and diffuse quantization error across color channels in an opponent color representation. Thus, the noise is shaped into frequency regions of reduced human color sensitivity. To obtain the optimal filter, we derive a matrix version of the Yule-Walker equations which we solve by using a gradient descent algorithm. Finally, we show that the vector error filter has a parallel implementation as a polyphase filterbank.     

精密两维转镜的动力学仿真与控制误差分析

精密两维转镜作为激光角度欺骗干扰半实物仿真试验系统中模拟弹目、弹干扰视线运动的重要设备,其控制误差是影响视线运动模拟精度的重要因素,进而影响半实物仿真试验精度。以多体系统动力学方法推导了精密两维转镜的机电分析动力学模型,采用计算力矩法设计了两维转镜的轨迹跟踪控制器,并在Matlab/Simulink环境中对建立的反映转镜动态特性的数学模型进行了仿真,转镜方位、俯仰轴对等效正弦输入信号的角位置跟踪误差分别为2.2 mrad与3.5 mrad,结果表明:模型可实现对引导输入的角位置信号的高精度跟踪控制。     

Masquerade detection augmented with error analysis

A masquerade attack, in which one user impersonates another, may be one of the most serious forms of computer abuse. Automatic discovery of masqueraders is sometimes undertaken by detecting significant departures from normal user behavior, as represented by a user profile formed from system audit data. A major obstacle for this type of research is the difficulty in obtaining such system audit data, largely due to privacy concerns. An immense contribution in this regard has been made by Schonlau et al., who have made available UNIX command-line data from 50+ users collected over a number of months. Most of the research in this area has made use of this dataset, so this paper takes as its point of departure the Schonlau et al. dataset and a recent series of experiments with this data framed by the same researchers . In extending that work with a new classification algorithm, a 56% improvement in masquerade detection was achieved at a corresponding false-alarm rate of 1.3%. In addition, encouraging results were obtained at a more realistic sequence length of 10 commands (as opposed to sequences of 100 commands used by Schonlau et al.). A detailed error analysis, based on an alternative configuration of the same data, reveals a serious flaw in this type of data which hinders masquerade detection and indicates some steps that need to be taken to improve future results. The error analysis also demonstrates the insights that can be gained by inspecting decision errors, instead of concentrating only on decision successes.