Showing papers by "Sabah M. Ahmed published in 2003"

Design of FIR filters with arbitrary amplitude and phase specifications using genetic algorithm

Abstract: In this paper we present efficient design algorithm for FIR filters with arbitrary amplitude and phase specifications using genetic algorithm. This algorithm provides flexibility in control the genetic algorithms parameters such as population size, number of generations, crossover probability and so on. Filters with binary, integer or real coefficients can be easily handled by the proposed method. This includes the multiplierless coefficients case. It has been tested for the design of filters with different amplitude and phase specifications. The fitness function was defined as the simple reciprocal of sum squared of the error.

High-quality low-complexity wavelet-based compression algorithm for audio signals

Abstract: Wavelets have recently emerged as a powerful tool for signal compression, particularly in the areas of image, video, and audio compression. In this paper, we present a low-complexity wavelet-based audio compression algorithm that is capable of handling fairly arbitrary audio sources. The algorithm transforms the incoming audio data into the wavelet domain, and compresses data by exploring redundancy in the wavelet coefficients and exploiting the large runs of zeros in the transformed signal. Also there is a possibility of applying a threshold to the non-zero coefficients, thus a further increase in the number of zeros is expected. The audio signal is first preprocessed to scale down the wavelet coefficients. Then the preprocessed signal is wavelet transformed using a bi-orthogonal discrete wavelet transform (DWT) and threshold by applying energy compaction strategy. Encoding represents the threshold coefficients in compact form. A new encoding technique that is easy to implement, and that provides a reasonable compression ratio for a certain acceptable distortion level has been developed to encode the threshold DWT. So, a bit rate can be controlled such that the algorithm operates at virtually any pre-selected bit rate. The motivation of using the bi-orthogonal wavelet transform is that it permits the use of a much broader class of filters, and this class includes symmetric linear phase filters. The superior performance of this algorithm is also demonstrated by comparing it with two other popular audio compression techniques and this meets the requirements of multimedia computing.

Design of IIR filters with simultaneous amplitude and group-delay characteristics using genetic algorithm

Abstract: This paper presents a new technique for the design of IIR digital filters with simultaneous amplitude and group-delay requirements The filter stability is guaranteed by controlling the poles' positions and the filter delay This algorithm is based on genetic algorithm where the genetic parameters such as population size, number of generations, and crossover probability are adopted for designing filters with power of two, integer or real coefficients The fitness function is defined as the simple reciprocal of sum squared of the magnitude and delay errors The proposed method has been tested for the design of filters with different amplitude and group-delay specifications