M. J. Mismar

Road traffic sign detection in color images

This work is a part of a smart system that can be used in autonomous vehicles or can assist drivers in locating road signs. The detection technique includes histogram equalization, light control and color segmentation. In this technique, both the HSV and the YUV color spaces are incorporated to achieve better segmentation results than that of one color space techniques.

Null Steering With Arbitrary Phase Perturbations Using Dual Phase Shifters

This work presents a new antenna configuration of dual phase shifters to steer multiple nulls by controlling the arbitrary phase perturbations. Consequently, the nonlinear problem of the perturbed element phases is transformed to a linear problem to obtain intermediate parameters, which are the cosine function of the perturbed phases. The linear programming approach is used to calculate the intermediate parameters. The computer simulations demonstrate the validity and the simplicity of this method.

Genetically evolved phase-aggregation technique for linear arrays control

This paper presents a modified Genetic Algorithm (GA) technique in which the large phase perturbations are calculated by aggregating small phase increments. The proposed aggregation GA technique overcomes the major drawback of the large solution space required by the classical GA techniques. The proposed method adopts small ranges for increments of the parameters and the optimality is reached via aggregation of the best increments of phases. Consequently, the GA searches in a smaller solution space and finds the solution with reduced number of iterations. Simulation results show the achieved improvement of the proposed technique over the classical GA. The suppressed sectors using phase-only control are accomplished with and without element failures. Problems like imposing symmetrical nulls around the mainbeam and compensation for the failure of center element have been achieved.

Pattern Nulling By Iterative Phase Perturbation

This paper presents a method for linear array pattern synthesis with multiple suppressed sectors using phase-only control of the antenna elements. Large phase perturbations are obtained by solving the nonlinear problem using an iterative procedure with linear programming. This technique can impose symmetrical and non-symmetrical suppressed sectors in the perturbed pattern. The full phase-only control is accomplished as well as the partial control of the edge elements. The partial control leads to a significant reduction in the number of phase shifters used for sector suppression as compared to the full control implementation.

Design of Linear Phased Array for Interference Suppression Using Array Polynomial Method and Particle Swarm Optimization

In this work, a linear phased array pattern design with null steering is achieved using the array polynomial technique and the Particle Swarm Optimization (PSO) algorithm. The null steering for interference suppression is obtained by controlling some of the roots on the Schelkunoff’s unit circle while keeping the roots responsible for the main beam unchanged. The rest of the roots are controlled to minimize the Side Lobe Level (SLL) of the array pattern using the PSO algorithm. It has been demonstrated that this technique achieved more than 50% reduction in the parameters needed to be optimized compared with the conventional complex coefficients optimization techniques. Consequently, the fitness function is only responsible for the SLL as the prescribed controlled nulls and the mainbeam characteristics are solved analytically. The simulated results show the effectiveness of the proposed technique.

Null steering using the minimax approximation by controlling only the current amplitudes

A linear programming technique using the minimax approximation to steer the nulls of an array by controlling the current amplitudes is presented. The technique determines the current amplitudes that produce the minimum sidelobe level for a given beam width and prescribed nulls in arbitrary directions. The results show the ability of this technique to steer the nulls in the sidelobe region while maintaining the main beam directed towards the desired signal. This technique also allows the number of controlled nulls to attain the full degrees of freedom for the array.

Genetically Evolved Phase-Aggregation Technique for Linear Arrays Control

This paper presents a modified Genetic Algorithm (GA) technique in which the large phase perturbations are calculated by aggregating small phase increments. The proposed aggregation GA technique overcomes the major drawback of the large solution space required by the classical GA techniques. The proposed method adopts small ranges for increments of the parameters and the optimality is reached via aggregation of the best increments of phases. Consequently, the GA searches in a smaller solution space and finds the solution with reduced number of iterations. Simulation results show the achieved improvement of the proposed technique over the classical GA. The suppressed sectors using phase-only control are accomplished with and without element failures. Problems like imposing symmetrical nulls around the mainbeam and compensation for the failure of center element have been achieved.

Partial control for wide-band interference suppression using eigen approach

This paper presents a simple and efficient array pattern synthesis technique for multiple wideband interference suppression using only the edge elements of linear arrays. By minimizing the mean-square value of the pattern in the directions of interference, the eigenvector that corresponds to the minimum eigenvalue is computed to obtain the required current excitation of the edge elements, the number of computations is greatly reduced since partial amplitude control of the edge elements is used.

Pattern Synthesis with Phase-Only Control using Array Polynomial Technique

A new synthesis technique using the phase shifters of the linear array elements is developed using the array polynomial technique. The array factor is expressed as the product of sub polynomials such that their roots are located on the unit circle. All array elements are active for any arbitrary non-prime number of the array elements. The results show that the developed method in the form of an analytical solution can synthesize the prescribed patterns using the phase shifters of the linear antenna arrays.

Chebyshev approximation for linear phase nonrecursive digital filters

A procedure has been developed for the design of nonrecursive digital filters with prescribed passband and stopband amplitude characteristics. The proposed procedure is based on an efficient algorithm utilizing the simplex method of linear programming. The design algorithm yields equiripple approximation and it is an alternative to the one which is based on the Remz exchange algorithm. The design procedure allows exact specifications for arbitrary passband and stopband edges. Furthermore, no prior knowledge of the degree of the filter is required. To demonstrate the potential of the design algorithm, several examples with different requirements are worked out and a sample is presented. The obtained results show that the design procedure performed very well where the various parameters of the filter were taken into consideration.