Abhijit Chandra

A novel approach for coefficient quantization of low-pass finite impulse response filter using differential evolution algorithm

Evolutionary computational techniques have been employed judiciously in various signal processing applications of late. In this paper, such an attempt has been made to design a low-pass linear-phase multiplier-less finite duration impulse response (FIR) filter using differential evolution (DE) algorithm. This particular evolutionary optimization technique has been explored to search the impulse response coefficients of the FIR filter in the form of sum of power of two (SPT) in order to avoid the multipliers during design process. The performance of the designed low-pass filter has been studied thoroughly in terms of its frequency characteristics and primitive requirement of fundamental hardware blocks. The superiority of our design has been ascertained over a number of existing techniques by various means. Finally, the proposed filter of different lengths has been implemented on a field programmable gate array (FPGA) chip for evaluating the competency of this work. The percentage improvement in hardware complexity produced by our design has also been computed and clearly listed in this paper for convenience.

Role of Mutation Strategies of Differential Evolution Algorithm in Designing Hardware Efficient Multiplier-less Low-pass FIR Filter

In recent times, system designers are becoming very much apprehensive in reducing the structural complexity of digital systems with which they deal in practice. However, the uncontrolled minimization of any digital hardware always leads to significant deterioration of system performance making it incompatible for use in any practical system. As proper trade-off is inevitably essential between achievable performance and required hardware, researchers have sought a number of artificially intelligent optimization techniques to solve it out. Since such a technique generally involves variety of constructional alternatives, appropriate use of correct option demands justified attention. Numerous evolutionary computation techniques, being a branch of biologically inspired optimization process, are being increasingly used for a number of signal processing applications of late. This paper throws enough light to select the most suitable mutation strategy of Differential Evolution (DE) algorithm for efficient design of multiplier-less low-pass finite duration impulse response (FIR) filter. Computationally efficient mutation scheme has been identified by observing convergence behavior and error histogram plot for different alternatives. Performance of the designed filter has been compared in terms of its magnitude response and the requirement of various hardware blocks for four different lengths of the filter. Consequently the name of the most favorable mutation rule has been suggested upon analyzing all the factors. Finally the supremacy of our proposed design has been established by comparing its performance with that of other state-of-the-art multiplier-less low-pass FIR filters.

A new strategy of image denoising using multiplier-less FIR filter designed with the aid of differential evolution algorithm

Due to the rapid development of one-dimensional signal processing in last few decades, it has spread out its wings in the field of multi-dimensional signal processing too. This has mainly been dominated by the proposition and implementation of robust algorithms which have focused on efficient storage and reliable transmission of digital images of various kinds. During the transmission through wired or wireless medium, digital images often encountered different types of channel noise which can significantly distort its appearance. As a matter of fact, filtering operation of digital images forms one of the most important tasks to be performed at the receiving end. In this paper, we have proposed a novel design strategy of two-dimensional (2-D) low-pass filter by means of a powerful evolutionary optimization technique called Differential Evolution (DE) algorithm. Mask coefficients of the proposed filter are constrained to assume values as sum of powers-of-two, thus making the filter hardware friendly. Experimental results have demonstrated the power of the algorithm in reducing the effect of Gaussian noise from digital image in terms of various performance parameters like peak signal-to-noise ratio (PSNR), structural similarity index measure (SSIM), image enhancement factor (IEF) and image quality index (IQI) and so on. A number of test images have been taken into our consideration for the purpose of establishing our proposition. Simulation results have confirmed the superiority of the proposed DE-based filter over the conventional low-pass filtering method.

Optimization of Control Parameters of Differential Evolution Technique for the Design of FIR Pulse-shaping Filter in QPSK Modulated System

Signal Processing in modern era, involves rigorous applications of various evolutionary algorithms such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Differential Evolution (DE) for the optimized design of aerodynamic shape, automated mirror, digital filter, computational intelligence etc. DE has been judged to be quite effective in designing different types of digital filter with good convergence behavior. The performance of the DE optimization technique could be improved to a further extent if the values of the two control parameters namely “Weighting Factor” and “Crossover Probability”, be chosen properly. In this paper, the effect of these two control parameters on the design of low pass FIR digital filter has extensively been studied. The impact of these control parameters on the convergence behavior of the DE technique has also been presented. The performance of the DE optimized filter has been adjudicated in terms of its magnitude and impulse responses. In addition, the DE optimized filter has been utilized as a pulse-shaping filter in a Quadrature Phase Shift Keying (QPSK) modulated system and its performance has further been studied in terms of Bit Error Rate (BER). Finally, the optimized values of the ‘’Weighting Factor’’ and “Crossover Probability” for this specific modulated system design problem has been recommended. Experimentally measured Eye diagrams have also confirmed the optimized values.

Optimization of control parameter of Differential Evolution algorithm for efficient design of FIR filter

Modern signal processing applications invoke various evolutionary algorithms in different areas such as aerodynamic shape optimization, pattern recognition, digital filter design, automated mirror design etc. Presently, Differential Evolution (DE) algorithm has proved to be quite efficient in these areas. Digital filters of various kinds can be designed using this particular evolutionary technique. In this paper, we have studied the effect of an important control parameter namely, the Weighting Factor, on the convergence speed of the DE algorithm, associated with the efficient design of low-pass FIR filter being used subsequently as a pulse-shaping filter in a QPSK modulated system. Finally, the optimized value of the Weighting Factor for this specific design problem has been suggested. Experimentally measured Eye diagrams confirm the optimized value.

Detection of Cerebral Aneurysm by Performing Thresholding-Spatial Filtering-Thresholding Operations on Digital Subtraction Angiogram

Cerebral aneurysm (CA) has been emerging as one of the life threatening diseases which have developed a deep concern amongst the neurologists in recent years. To be specific, it shows devastating characteristic due to the formation of abnormal bulging of artery in human brain followed by its rupture. Therefore detection of this abnormality prior to the rupture becomes inevitably essential to save our lives to a great extent. This paper throws enough light in detecting cerebral aneurysm of various sizes by combining the operations of spatial filtering and thresholding in an elegant way. A number of Digital Subtraction Angiogram (DSA) images, affected by cerebral aneurysm of various magnitudes, have been taken into consideration in this connection. Finally, the affected area has been marked with red colour to make it more prominent than the other parts of the image.

Design optimisation of powers-of-two FIR filter using self-organising random immigrants GA

In this communication, we propose a novel design strategy of multiplier-less low-pass finite impulse response (FIR) filter with the aid of a recent evolutionary optimisation technique, known as the self-organising random immigrants genetic algorithm. Individual impulse response coefficients of the proposed filter have been encoded as sum of signed powers-of-two. During the formulation of the cost function for the optimisation algorithm, both the frequency response characteristic and the hardware cost of the discrete coefficient FIR filter have been considered. The role of crossover probability of the optimisation technique has been evaluated on the overall performance of the proposed strategy. For this purpose, the convergence characteristic of the optimisation technique has been included in the simulation results. In our analysis, two design examples of different specifications have been taken into account. In order to substantiate the efficiency of our proposed structure, a number of state-of-the-art design strategies of multiplier-less FIR filter have also been included in this article for the purpose of comparison. Critical analysis of the result unambiguously establishes the usefulness of our proposed approach for the hardware efficient design of digital filter.

Efficient encoding of powers-of-two coefficients through minimum index floating point representation (MIFPR)

Reduction of hardware complexity of digital system has grown enormous interest amidst the researchers of late. As a matter of fact, a number of hardware efficient digital systems have been emerged in practice among which multiplier-less architecture is the most popular and effective one. Multiplier-less configuration restricts the tap-coefficients of any digital filter to assume values from a finite set encoded as sums and/ or differences of powers-of-two. In this paper, we have proposed a new scheme, called minimum index floating point representation (MIFPR), for the efficient design of multiplier-less filter. Comparative analysis of the proposed technique with some of the existing representation schemes related to power-of two filters has been presented and subsequently the best alternative has been suggested. Analytical results have also been substantiated by proper simulation results.

Novel design strategy of multiplier-less low-pass finite impulse response filter using self-organizing random immigrants genetic algorithm

Intelligent optimization techniques are playing a very vital role in solving a wide variety of problems of engineering and technology of late. In order to meet the challenges from various perspectives, researchers are always in favor of applying those approaches to get rid of numerous practical difficulties of concern. Digital signal processing, more specifically the design of digital filters in particular, has been immensely motivated and beneficiated by means of this amalgamation. In this communication, we have incorporated a recently proposed genetic optimization method, named as self-organizing random immigrants genetic algorithm, in multiplier-free finite impulse response filter (FIR) design algorithm. Our study has focused on the selection of optimum settlement of filter coefficients through the utilization of this population-based technique which results in power of two distribution of impulse response over a binary search space. The performance of our designed filter has been thoroughly analyzed by a number of design parameters of interest and compared with other state-of-the-art multiplier-less FIR models. It has been observed that the proposed approach outperforms the other designs by a considerably large margin in those areas of signal processing where the reduction in hardware cost is the biggest challenge.

An efficient algorithm to minimize the number of coefficients of an FIR pulse-shaping filter

Finite duration Impulse Response (FIR) filter has found its widespread applications in the field of communication as well as digital signal processing because of its attractive features, such as, linear phase response, assured stability etc. In modern digital or mobile communication system, transmitting pulse-shaping filters are more commonly realized by FIR filter. However, such a filter requires quite a large number of filter coefficients as compared to an Infinite duration Impulse Response (IIR) filter and hence leads to greater computational complexity. In this paper, an efficient algorithm has been proposed for the minimization of the number of coefficients of standard Raised Cosine (RC) pulse-shaping filter of different lengths, without affecting its performance to a great extent. The performance of the designed filter has been studied in terms of its impulse response as well as magnitude response. The designed FIR filter has also been used as a pulse-shaping filter in a Quadrature Phase Shift Keying (QPSK) modulated system and its performance has been studied in terms of the system Bit Error Rate (BER) value. From the simulation results it has been established that the newly proposed filter provides a significant reduction in the number of tap coefficients without much degradation in its performance.