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。     

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     

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     

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.      

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。     

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.     

直流弱电流测量与误差分析

介绍了分流式和反馈式电流表测量直流电流的基本原理。根据静电计测量直流弱电流信号的电路模型,分析了电流表输入端压降、源内阻、源电容、正确接地、连接导线、环境湿度等因素产生的测量误差,并且给出了相应的解决方案。     

弹载合成孔径雷达成像处理及定位误差分析

论文基于弹载合成孔径雷达（SAR）空间几何关系，描述了雷达信号数学模型；给出了弹载SAR成像方法；详细分析了弹载SAR水平初始方位角，载体速度的测量误差对于成像定位的影响；推导了各种误差影响成像结果的数学表达式；给出了非直线运动大下冲角情况下，误差分析的计算机仿真和在匹配制导中的实验结果。     

四象限探测器解算模型误差分析

针对四象限探测器的解算精度问题,研究了基于不同光斑模型计算方法存在的误差,重点分析了基于高斯分布的光斑模型和基于均匀分布的光斑模型在解算结果上的差异,利用图像处理技术和建模仿真技术,从理论上得出,无论是哪种光斑模型,本身都存在计算模型误差,通过量化为工程应用提供重要参考。     

基于激光传感器的统计特征提取和误差分析

近年来, 激光测量系统(LMS)在各个研究领域中的应用日益增多。基于激光的距离测量技术具有较高的精度和速度,方向性好,能够以较高的频率提供分辨率高、准确性好的距离信息。常用的二维脉冲式激光传感器,测量到的有限长数据序列是一个关于环境的扫描平面。其测量数据的获取质量受到诸多环境因素影响。文中基于LMS 221激光传感器的应用,对不同材质物体的测量进行了误差分析,总结了由于物体表面特性、漂移和距离等因素对测量精度造成的影响。通过分析不同材质的测量数据,可有效地对测量物体进行大致分类,并对检测的误差进行补偿以提高测量精度。     

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.     

四象限探测器解算模型误差分析

针对四象限探测器的解算精度问题,研究了基于不同光斑模型计算方法存在的误差,重点分析了基于高斯分布的光斑模型和基于均匀分布的光斑模型在解算结果上的差异,利用图像处理技术和建模仿真技术,从理论上得出,无论是哪种光斑模型,本身都存在计算模型误差,通过量化为工程应用提供重要参考。     

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.     

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.