基于全通滤波器的IIR陷波器抑制信号中的周期性干扰

从滤波器的系数敏感度角度 ,提出一种基于全通滤波器的 IIR陷波器来抑制信号中的周期性干扰。该滤波器是由全通滤波器的级联构成的 ,因为全通滤波器传递函数的分子和分母多项式之间的镜像对称关系 ,该滤波器可以用高效的格型运算结构来实现 ,并且具有很低的系数敏感度 ,使得系数量化后的陷波频点偏移量最小。本文详细论述了该陷波器的设计方法 ,并深入分析了其在低频段的系数敏感度问题。通过实际数据验证了这种滤波器能够有效的抑制电力线通信信号中的谐波干扰。     

High order stable infinite impulse response filter design using cuckoo search algorithm

In this paper, an efficient technique for optimal design of digital infinite impulse response (IIR) filter with minimum passband error (e _p ), minimum stopband error (e _s ), high stopband attenuation (A _s ), and also free from limit cycle effect is proposed using cuckoo search (CS) algorithm. In the proposed method, error function, which is multi-model and non-differentiable in the heuristic surface, is constructed as the mean squared difference between the designed and desired response in frequency domain, and is optimized using CS algorithm. Computational efficiency of the proposed technique for exploration in search space is examined, and during exploration, stability of filter is maintained by considering lattice representation of the denominator polynomials, which requires less computational complexity as well as it improves the exploration ability in search space for designing higher filter taps. A comparative study of the proposed method with other algorithms is made, and the obtained results show that 90% reduction in errors is achieved using the proposed method. However, computational complexity in term of CPU time is increased as compared to other existing algorithms.     

Computationally efficient algorithm for reducing the complexity of software radio receiver's filter bank

In this paper, a computationally efficient method for extracting individual radio channels from the output of the wideband analog to digital converter (ADC) is presented. In a software radio, the extraction of individual channels from the output of the wideband ADC is by far the most computationally demanding task; hence it is very important to devise computationally efficient algorithms for this task. We proposed a new algorithm by assuming the symmetric signal with periods of the length-P (number of coefficients in low pass filter prototype) as an input signal to the subsampled filter bank. Also we divide the complex input x[n] into real and imaginary parts, then we perform operations in each part using two parallel filter banks. Finally, we add the outputs in two parts. By employing this algorithm to the subsampled filter bank channelizer, the complexity of the proposed algorithm was reduced by considerable amount of 81%.     

Digital IIR Filter Design Using Adaptive Simulated Annealing

Chen, S., Istepanian, R., and Luk, B. L., Digital IIR Filter Design Using Adaptive Simulated Annealing, Digital Signal Processing11 (2001) 241–251Adaptive infinite-impulse-response (IIR) filtering provides a powerful approach for solving a variety of practical problems. Because the error surface of IIR filters is generally multimodal, global optimization techniques are required in order to avoid local minima. We apply a global optimization method, called the adaptive simulated annealing (ASA), to digital IIR filter design. An important advantage of the ASA is the simplicity in software programming. Simulation study involving system identification application shows that the proposed approach is accurate and has a fast convergence rate, and the results obtained demonstrate that the ASA offers a viable tool to digital IIR filter design.     

Time domain approximation using digital methods

Two digital methods are proposed for the solution of the time-domain approximation problem. Tho first method, based on a reeursivo algorithm for tho matrix pseudo-iriverso, determines the pulse transfer function of a discrete-timo system of a prescribed order providing the best fit in tho least squares sense at tho samplo points. Tho continuous-time system transfer function is then derived by using a simple transformation provided that tho sampling frequence oxeeeds tho Nyquist rate. Tho method is direct and computationally efficient. The second method is based on using an offieiont gradient search algorithm providing the best fit in the least pti sense at tho samplo points. A number of examples illustrato the methods     

Nonlinear mappings in problem solving and their PSO-based development

The study is devoted to a concept and algorithmic realization of nonlinear mappings aimed at increasing the effectiveness of the problem solving method. Given the original input space X and a certain problem solving method M, designed is a nonlinear mapping ? so that the method operating in the transformed space M(?(X)) becomes more efficient. The nonlinear mappings realize a transformation of X through contractions and expansions of selected regions of the original space. In particular, we show how a piecewise linear mapping is optimized by using particle swarm optimization (PSO) and a suitable fitness function quantifying the objective of the problem. Several families of problems are investigated and illustrated through illustrative experimental results.     

Design of IIR filters using a pole-zero mapping approach

This paper presents a new technique for designing IIR filters that have minimum deviation from equiripple response. The algorithm is also able to find transfer functions with unequal numerator and denominator orders, which are suitable for both digital and analog IIR sampled-data realizations. Elliptic filters are produced as a particular case, when equal numerator and denominator orders are specified. Pole-zero mapping is used for scalar update of optimization parameters, thereby reducing the algorithm complexity. Zeros are structurally allocated on the unit circumference for efficient stopband shaping. Moreover, filter stability is easily enforced by restricting the radii of the poles to be lower than 1. A Taylor series expansion is employed to determine the step size of the parameter updates. The proposed approach is based on evaluations of partial cost functions to avoid local minima, and hence increase the robustness and the convergence rate of the optimization process. Design examples are shown to illustrate the efficacy of the proposed design technique, compared to alternative design techniques.     

一种基于TMS320C5402的数字IIR滤波器设计

数字IIR滤波器广泛地应用于数字信号处理领域。本文主要介绍了如何在定点DSP芯片上实现IIR数字滤波器，并且通过对IIR滤波器结构的分析，对IIR数字滤波器作了一定简化，使得在定点DSP芯片上容易实现。本文采用TI公司的C54系列DSK并结合MATLAB进行仿真，达到了预期的效果。     

Analysis of magnetic aftereffect by using Monte Carlo methods

Magnetic aftereffect phenomena are simulated in the framework of phenomenological models of hysteresis by using the Monte Carlo technique. It is shown that a log t-type dependence of the average value of the output variable (usually the magnetization) can be qualitatively predicted by using simplified models of hysteresis with local memory, such as the Jiles–Atherton, Hodgdon, or the Energetic model. These models are computationally much more efficient than the more elaborate models of hysteresis with global memory like the Preisach model. Numerical results related to the decay of the output variable as of function of time are presented. The viscosity coefficient as well as the temperature dependence of the viscosity coefficient is analyzed in detail.     

The minimal order of rational transfer function realization from its z-domain samples

We present here a new method for realization of minimal-order proper rational transfer functions from z-domain samples. A criterion for determining the minimal order of the transfer function is given. The theory is developed first for strictly proper rational transfer functions and then extended to the case of transfer functions with a direct-coupling term. The theory is valid for arbitrary z-domain samples. The special case of uniform frequency response samples is shown to allow a computationally efficient derivation of the realization. Examples are given to illustrate the theory. The theory developed here has many applications, such as modelling of communication channels, identification of systems from frequency measurements and infinite impulse response filter design.     

Design of wideband CIC compensator filter for a digital IF receiver

This paper presents the multiplierless CIC compensation filter based on the 2M-order filter and the sharpening technique. This technique proposed by Kaiser and Hamming attempts to improve the pass band and the stop band of a symmetric nonrecursive filter using the multiple copies of the same filter. We have considered the simplest sharpening polynomial that improves the frequency characteristic with minimum increase in computational complexity. The proposed filter provides wideband compensation over the specified CIC main lobe bandwidth. The design parameter is a single integer b which depends on K, the number of cascade CIC stages and is independent on the decimation factor M. The values of b tabulated here were obtained from MATLAB simulations. A number of demonstrated characteristics make the proposed structure a good candidate for software defined radio (SDR) applications.     

A recursive algorithm for estimating multiple models continuous transfer function with non-uniform sampling

A multiple model recursive least squares algorithm combined with a first-order low-pass filter transformation method, named λ-transform, is proposed for the simultaneous identification of multiple model orders continuous transfer functions from non-uniformly sampled input–output data. The λ-transformation is shown to be equivalent to a canonical transformation between discrete z-domain and δ-domain using the negative value of the λ-transform filter time-constant instead of the sampling interval parameter. The proposed algorithm deals with oversampling, sampling jitter or non-uniform sample intervals without the need for extra digital anti-aliasing pre-filtering, downsampling or interpolation algorithms, producing multiple models with a cost function that facilitates automatic selection of best-fitted models. Besides, measurement noise is noted as beneficial, bringing up an inherent bias toward low-order models. Simulated examples and a drum-boiler level experimental result exhibiting non-minimum phase behaviour illustrate the application of the proposed method.     

An improved lexicographic search algorithm for the flowshop scheduling problem

This paper describes an improved lexicographic search algorithm for the solution of the n-job, M-machine flowshop scheduling problem. The proposed improved algorithm is capable of generating all optimal schedules for any monotonically non-decreasing optimality criterion and is computationally more efficient than the basic lexicographic search algorithm. A numerical example is solved to illustrate the decrease in the computational effort by the proposed algorithm.     

基于U-LMS算法的船舶自适应逆控制

自适应逆控制的基本思想就是要用一个来自控制器的信号去驱动对象,而该控制器的传递函数就是参考模型与该对象建模函数的商.按照某一种自适应算法,用对象和指令输入之差的误差信号来调节控制器的参数以使该误差信号的均方差最小.根据IIR算法的快速收敛性,该文设计了基于U-LMS算法的IIR控制器,并把其应用到船舶模型控制上,仿真结果表明这种控制器大大减少了计算量,快速性得到了提高,并且权值的失调较小,对于参考模型的输出具有非常优良的跟踪性能.     

Observer design for discrete systems with unknown exogenous inputs

A design procedure is developed for determining optimal discrete observers for estimating system states and unknown exogenous system inputs. This procedure is based on augmenting a standard system observer with an input model. The augmented model is then transformed into the discrete z-domain to determine relevant input/output transfer function matrices. The transfer function matrices are used to develop transfer function relationships between unknown exogenous inputs and the observer estimate of these inputs. It is shown that the optimal observer gains can be determined by implementing the observer as a Fisher filter. An example of the procedure is demonstrated with a third-order point-mass tracking filter     

3-D curve matching using splines

A machine vision algorithm to find the longest common subcurve of two 3-D curves is presented. The curves are represented by splines fitted through sequences of sample points extracted from dense range data. The approximated 3-D curves are transformed into 1-D numerical strings of rotation and translation invariant shape signatures, based on a multiresolution representation of the curvature and torsion values of the space curves. The shape signature strings are matched using an efficient hashing technique that finds longest matching substrings. The results of the string matching stage are later verified by a robust, least-squares, 3-D curve matching technique, which also recovers the Euclidean transformation between the curves being matched. This algorithm is of average complexity O(n) where n is the number of the sample points on the two curves. The algorithm has applications in assembly and object recognition tasks. Results of assembly experiments are included.     

A Recursive Digital Filter Implementation for Noisy and Blurred Images

This paper presents the design and the implementation of an optimized Canny-Deriche edge detector. After a brief reminder of the filter's equations, we define different techniques to speed up the sampling rate of the IIR filter. In particular, improving the throughput rate of the IIR filter, we present a look-ahead with decomposition technique. This method leads us to design a first chip, which performs at a sampling rate of over 20 MHz with a silicon area of 60 mm². Using a local register retiming method, we have designed a second circuit, which is able to process a pixel in 30 ns with a silicon area of 30 mm². These two approaches are compared. This work leads us to an ASIC which was designed in a CMOS 1 μm technology and successfully tested.     

GC^1约束的三角Bézier曲面降阶逼近研究

研究给定的n次三角Bézier曲面在L2范数下的一次降多阶的逼近问题,给出了在无约束条件下的三角Bézier曲面降阶求解的详细过程,将降阶问题转化为非线性最优化问题求解,并将降阶过程与曲面的几何连续拼接结合在一起,给出了降阶同时满足GC^1拼接的实现过程。实验结果表明,该方法简单实用,降阶逼近效果好。     

Real-time extraction of water surface boundary using shipborne radar

ABSTRACT

Real-time water boundary extraction with high accuracy is still a challenging problem in remote-sensing field. This article presents a shipborne water surface boundary extraction technique by integrating civilian marine radar and GPS compass. Meanwhile, a framework is developed to automatically extract water boundary from radar image. In this framework, direct transformation is adopted to rectify the geometric distortion of the radar image, morphological operation is used to fill holes and filter speckles in image, an edge tracing algorithm is design to extract image boundaries, visibility analysis and optimizations are conducted to recognize the real water surface boundary and to produce a vector map. A case study in Nanjing reach of Yangtze River are intended to validate performances of the method, and the final output of this method is verified using synchronous and detailed GPS-RTK (real-time kinematics) survey points. The experimental results demonstrate that the proposed water boundary extraction method can reach a positioning accuracy within ±1 m, which is significantly better than that of satellite-based optical remote-sensing and synthetic aperture radar (SAR) techniques, and the algorithm is computationally efficient and has the capability of real-time, full-automatic water boundary generation for various applications.