New Approach for Simultaneously Estimating Output SNR and Angle of Arrival (AOA) with New Array Configurations

In order to define the location of any electromagnetic transmitting source, two or three directions of arrival (θ,Ø) estimators are needed to provide two or three different directions for coordination. In the last two decades most of research works are focused on Multiple Signal Classification (MUSIC), and Estimation of Signal Parameters using Rotational In-variance Techniques (ESPRIT) techniques, since they provide high (AOA) estimation accuracy. Most of researcher assumed the arrays are linear and planner formed from isotropic elements. In practical case, the array antennas are formed from short or half wave dipoles; these types of element lead to many difficulties, since the field pattern are no longer isotropic. They have a pattern directivity function of spatial angles, so by using short dipoles as linear array element, it is so difficult to have a fixed output SNR for all angles of arrival for estimated signals. In this paper, we introduce a new approach to overcome this problem and by this approach we get a fixed output SNR regardless arriving angles of received signals. The proposed approach offers a simultaneous estimation for output SNR and AOA with voice channel based on a practical field scenario (battle field condition) by using phased adaptive array system with new array elements configuration and algorithm. A linear phased adaptive array element is shifting by predetermined angle (α), which is depending on the number of array elements and on a spatial span that must be covered. A modified LMS algorithm is used to make adaptive array antenna works as angle of arrival (AOA) estimator rather than noise and jammer canceller. The results show that the proposed system can accurately and simultaneously estimate AOA as well as the output SNR for all arriving angles and also provides voice channel for listening which is needed for electronic warfare activities. The results show that the estimated output SNR level is fixed over the coverage spatial span regardless the direction of arrival of received signals. By using parallel linear array elements [without shifting (α=0)] the output SNR level no more fixed and it directly depends on the arriving angle of received signal. Finally, the theoretical analysis and simulation results show that there is an interesting relationship between largest Eigenvalue λmax of orthogonalized received signals covariance matrix Ø
_xx
and the output SNR of estimated signal which is (λmax=SNR+1).