基于CORDIC的FFT处理器设计

波束形成是阵列信号处理过程的一个重要步骤,它在雷达、地质勘探、医学成像领域起着关键的作用并得到了广泛的应用。在声呐系统中,FFT处理器是波束形成器的关键部件,论文中引用了CORDIC算法,并对比了基2、基4等时域FFT算法的区别,根据基本原理和流程最终选定了基4算法,将其有效地和CORDIC算法结合起来。设计了一款基于CORDIC算法的FFT处理器。采用流水线方式,形成了5级蝶形算法,满足了FFT运算要求。     

基于CORDIC算法的流水线型FFT处理器设计

首先分析了基二FFT算法的原理以及在FPGA上实现FFT处理器的硬件结构。其次详细研究了在FPGA上实现FFT的具体过程,利用CORDIC算法实现了旋转因子乘法器,解决了整体设计过程中主要面对的几个关键问题,最终利用Verilog编程实现了基二流水线型FFT处理器,利用MATLAB与MODELSIM结合仿真结果表明该设计满足FFT处理器的基本要求,在10 MHz的采样率下完成32点FFT只需要14.45μs,设计方法也简单易行,具有一定的推广价值。     

基于CORDIC算法的基4DIT-FFT处理器的设计

随着海洋开发和信息产业的发展,高速、大容量、高可靠性的水声通信系统成为研究热点。论述了一种用于水声通信系统中的基4DIT-FFT处理器的设计。该设计利用CORDIC算法优化蝶形运算单元,将复数乘法转换为硬件易于实现的加、减、移位运算,并通过Matlab对伸缩系数与旋转系数进行预处理,大大加快了运算速度且降低了系统复杂性。在此基础上设计了一种1024点12位的基4DIT-FFT处理器。     

Fixed-point error analysis of discrete Wigner-Ville distribution

The Wigner-Ville distribution (WVD) has been a powerful signal processing tool for time-frequency signal analysis. Consequently, many algorithms have been proposed in the literature for computing the WVD in real-time applications. However, Boashash (1987) has proposed and showed that the evaluation of the analytic signal using the time-domain approach, and involving the Hilbert transformer, is the most efficient algorithm for real-time applications. A fixed-point error analysis of this algorithm has been carried out. The theoretical noise-to-signal ratio (NSR) is derived and verified through simulation. The results indicate that for this algorithm, the NSR increases by 0.5 bit/stage, whereas for the other algorithms, it increases by 1 bit/stage     

Fixed-point error analysis of two DCT algorithms

A fixed-point error analysis of two fast DCT algorithms proposed by Hou (1987) and Makhoul (1980) is presented. Expressions for error variances are derived and the results are compared with the simulation results. It is found that the simulation results and analysis results agree quite closely. This demonstrates the validity of the analysis. In addition, the two algorithms are compared in terms of their advantages and disadvantages     

Fixed-point error analysis of radix-4 FFT

Radix-4 FFT requires less number of multiplications than radix-2 FFT of the same size, and for the same throughput, it requires less hardware. Hence, quite often, radix-4 structure is preferred to radix-2 structure. This paper evaluates the error performance of radix-4 FFT algorithms (the input quantization error and the coefficient inaccuracy is not considered). The analysis assumes fixed-point two's complement arithmetic, with rounding in the case of multiplication, and truncation in the case of scaling. The predicted results of output noise agree closely with the computer simulation results. The different schemes of scaling for preventing arithmetic overflow are compared from the noise-to-signal ratio point of view. In comparison with radix-2, the radix-4 FFT has got a marginally better error performance.     

Fixed-point error analysis of radix-4 FHT algorithm with optimisedscaling schemes

The fixed-point error performance of the various fast Hartley transform (FHT) algorithms have been investigated. Scaling schemes have been proposed for each of the algorithms. However, due to their better error performance, only the decimation-in-time (DIT) FHT algorithms have been examined. The fixed-point error analysis of the radix-4 DIT algorithm is discussed first and is shown to agree closely with the simulation results. These results are then compared with the simulation results for radix-2 and split-radix algorithms. The scaling schemes are then optimised and the simulation results of the three algorithms are compared. It is concluded that the radix-4 DIT algorithm has the best error performance     

测量方差自适应的多传感器数据融合算法

针对测量方差预先设定对滤波精度的影响,提出了一种基于时空综合分析在线估算测量方差的方法,以充分利用多个传感器单次采样数据和单个传感器多次采样数据中蕴含的冗余和互补信息。改善了由于被测目标所处环境的先验信息匮乏而造成的建模误差问题。同时根据滤波误差协方差阵具有表示滤波精度的特性,实现系统中各传感器权系数动态合理的分配。最终给出了一种基于测量方差自适应的多传感器数据融合算法。通过蒙特卡罗仿真验证了该算法的有效性。     

一种基于误差传递的短波信道均衡方法

电离层的不同传播模式是导致短波数字通信出现码间串扰的主要原因,为克服码间串扰,本文提出一种基于误差传递的短波信道均衡方法,并以青岛-长春链路为例进行了数值仿真和天波试验.数值仿真和空间链路试验表明,与非线性数据定向均衡方法相比,本文方法得到的信息符号的误差方差降低了约50%,而且在低信噪比情况下更有优势.     

A note on the error propagation analysis of recursive least squaresalgorithms

The article comments on the error propagation analysis of recursive least squares algorithms presented by Ljung and Ljung (1985), Verhaegen (1989), and Haykin (1991). In particular, it corrects some incorrect statements about the error propagation given in the literature. It considers the problem of spatial adaptive filtering using the RLS minimization     

基于MIMO-DFE的BLAST接收机的差错传递控制的研究

近期对于BLAST(Bell Laboratories Layered space-time)的研究从平坦衰落信道转向频率选择性衰落信道,基于MIMO-DFE(Multiple-Input-Multiple-Output Decision Feedback Equalizer)的接收机结构因此受到了广泛的关注.然而由于这类接收机本身的反馈结构,性能可能会由于差错传递而大大下降.本文将传统判决反馈均衡器的差错传递控制方法推广到多入多出(MIMO)系统中,仿真结果表明,本文提出的带差错传递控制的接收机能够有效控制差错传递.     

Phase error correction method based on the Gaussian filtering algorithm and intensity variance

To overcome the invalid phase and phase jump phenomenon generated during the phase unwrapping, a phase error correction method based on the Gaussian filtering algorithm and intensity variance is proposed in this paper. First, a threshold of fringe intensity variance is set to identify and clear the phase in the invalid region. Then, the Gaussian filtering algorithm is employed to correct the phase order at the fringe junction, and then the absolute phase is corrected. Finally, the phase correction experiments of different geometric objects are carried out to verify the feasibility and accuracy of the proposed method. The method proposed in this paper can be extended to the correction of absolute phase error obtained by any coding method.     

A review of error propagation analysis in systems

Error propagation analysis in reliable systems has been studied widely. Unlike classical sensitivity analysis which investigates the range of system performance, the distribution function of system performance studies error propagation analysis. Thus, error propagation analysis is essentially a statistical analysis.This paper reviews and classifies current research articles in error propagation. An overview is presented of error propagation applied to various systems and models. A standard analysis procedure is also given. Finally, several conclusions are drawn. It is recommended that i) basic research on error propagation be carried out, ii) an efficient (least cost) method be developed to analyze large-size problems, and iii) human error be included in the system modeling. It is our opinion that error propagation analysis be treated as part of decision-making procedures in system analysis.Error propagation analysis is extremely important for expensive or rare-event systems. This report can benefit those who analyze these systems.     

基于CORDIC的一种高速实时定点FFT的FPGA实现

本文论述了一种利用CORDIC算法在FPGA上实现高速实时定点FFF的设计方案。利用CORDIC算法来实现复数乘法，与使用乘法器相比降低了系统的资源占用率，提高了系统速度[1]。设计基于基4时序抽取FFT算法，采用双端口内置RAM和流水线串行工作方式。本设计针对256点、24位长数据进行运算，在XilnxSpartan2E系列的xc2s300e器件下载验证通过，完成一次运算约为12μs，可运用于高速DSP、数字签名算法等对速度要求高的领域。     

光纤陀螺漂移误差动态Allan方差分析

提出采用动态Allan方差(DAVar,Dynamic Allan variance)方法对光纤陀螺实测数据进行分析,系统地分析了引起光纤陀螺漂移误差的随机噪声种类及其来源和特性,DAVar分析方法的优势在于不仅能确定各种随机漂移的系数,而且可以跟踪和描述信号随时间变化的稳定性.实验证明,DAVar分析是对光纤陀螺随机漂移进行研究的有效方法.     

利用方差分析法实现水中目标的判别

对潜艇目标存在性的判别一直是困扰反潜人员的一个课题,高阶累积量是处理高斯噪声的有效工具,分析海洋环境噪声和潜艇目标噪声的高阶谱特性,分别提取其双谱,结果发现其双谱最大值相差在7个数量级以上,说明双谱是判别目标存在性的有效特征.方差分析的实质是分析数据间的差异情况,从海洋噪声中识别潜艇噪声可以看作是分析某一因素变化对样本数据的影响情况.把有目标存在和无目标存在两种情况的海区噪声双谱特征作为样本,进行方差分析,发现当只有环境噪声时,零检验假设条件成立,而当有潜艇目标存在时,其F值远大于1,零检验假设条件不成立,表明该方法可用于判别目标的存在性.利用Jarque-Bera检验法,可验证样本数据满足总体方差相等的正态分布条件.     

流水线CORDIC算法的FPGA实现

坐标旋转计算机（CORDIC）算法可以将多种难以用硬件电路直接实现的复杂运算分解为统一的简单移位、加法运算,然后逐次逼近结果。这种方法很好地兼顾了精度、速度和硬件复杂度,因而在数字信号处理领域得到了广泛应用。首先简要介绍了CORDIC算法的原理,然后基于现场可编程门阵列（FPGA）实现了流水线结构的CORDIC算法,仿真结果表明,其输出误差很小,与理论值基本一致。     

光纤陀螺随机误差特性的小波方差分析

光纤陀螺各项随机误差的频率特性各不相同.小波变换的多分辨分析兼具时频分析和尺度分析的功能,故采用小波方差法来表征噪声在不同频率分量的变化情况,从而为特定环境下光纤陀螺的故障诊断以及误差分析提供参考.通过与传统的分析光纤陀螺随机误差特性的Allan方差法对比可知,只要小波基函数的支撑区间足够小,小波方差就能克服Allan方差能量泄露的缺点.利用60Co辐照源模拟空间辐照,进行光纤陀螺整机辐照实验,分析实验数据,证明小波方差比Allan方差能够更加精确地反映光纤陀螺各项随机误差的变化情况.     

基于FPGA的CORDIC算法实现

针对传统CORDIC算法延时大,消耗资源多的缺点,在平行CORDIC算法的基础上提出了一种优化的平行算法,利用二进制转两极算法和微旋转角度编码对低部和高部的旋转方向进行预测,并在高部旋转中利用正反旋转抵消的策略来进一步减少旋转次数,提高运算速度。采用FPGA对提出的算法进行了硬件设计和验证,结果表明,计算迭代次数少,资源消耗少,精度较传统算法来说都有了明显改善。