This thesis is devoted to Determine the direction-of-arrival (DOA) of any signal of interest has long been of great interest to the research community. It is often required to identify the DOA of signals emanating from every possible direction. This is important for military as well as for civilian applications. The problem of estimation of the direction of arrival is presented, and the theory of different algorithms used for this purpose is reviewed for the necessary background. Theories and various techniques have been developed for array signal processing related to DOA estimations. In this thesis the enhancement to the direction of arrival estimation is described by using some popular DOA estimation algorithms , the multiple signal classification (MUSIC), Minimum Norm Method (MNM), Estimation of Signal Parameters via Rotational Invariance Technique (ESPRIT) algorithms and improved (MUSIC) algorithm based on lanczos process is present another method for DOA without necessary complete eigendecomposition. This method can be simply concluded as transforming the covariance matrix into tridiagonal matrix using proposed improved Lanczos process. Hence, the various techniques mentioned above are tested for their detection, resolution capabilities and performance capabilities of the Eigen Vector Decomposition , and to measure the affect of the different parameters upon the resolution of DOA estimation and detection such as SNR , number of sensors , number of snapshots , spacing distance between elements in the array ,separation angle between sources . A detailed study is performed for the purpose of comparing the performances of the aforementioned techniques and the result is that MUSIC is the best algorithm . MUSIC algorithm , is a basic method for the direction of arrival estimation (DOA). The resolution of the above techniques for the uniform linear array decreases as impinging signals get closer to the broadside direction, due to the array steering vector .Therefore one of the main efforts in this thesis is directed to investigate the performance of MUSIC and so different computer simulation programs were built to do this job , all simulations were made in Matlab ,the result of the simulation is that MUSIC exhibits an accurate estimation of DOA. But the comparison between Proposed method and MUSIC exhibited that Proposed method has better performance with respect to the different parameters, and it possesses lower standard deviation than MUSIC. Thus it is preferable for radar, sonar communication and passive detection systems ,which satisfied the main object of the thesis.