Moving Array Signal Processing Technology Based On Spatial And Temporal Extending

In the modern warfare environment, various radars, jamming transmitters, decoy systems and communication stations are deployed on a large scale. On this condition, the electromagnetic environment is increasingly complex, and the phenomenon of overlapped signals is growing. For locating emitters accurately to achieve some tactical intentions, the overlapped signals must be resolved firstly. In general, high-resolution direction of arrival (DOA) estimation of signals needs the supports of large aperture array. However, many tactical platforms are developed toward the trend of miniaturization, and the aperture will be limited strictly. On this condition, the conventional array signal processing cannot meet the demands of high-resolution DOA estimation. For resolving the conflicts of resolving power and array aperture, this paper will study the passive synthetic aperture technology from the point of spatial array extending and will study the temporal-spatial 2-dimension (2D) array signal processing technology from the point of temporal array extending. Based on the above two technologies, this paper attempts to achieve a highly resolving power using the lesser array aperture. The researches in this work are arranged as follows:In chapter 2, the passive synthetic aperture technologies for single sensor are studied. Firstly, the ambiguity of frequency and DOA is analyzed based on the uniformly moving single sensor model of passive synthetic aperture. Then a general processing algorithm of passive synthetic aperture for maneuverable single sensor is presented, and the optimized trajectory of single sensor for passive synthetic array is numerically analyzed. For improving the adaptability of frequency jitter which is caused mainly by the phase noise, an improved single sensor passive synthetic aperture algorithm which is suited for the phase noise model is introduced. The improved new algorithm can enhance the DOA estimation accuracy of pulse signal.In chapter 3, the passive synthetic aperture technology for moving linear array is studied. For processing the pulse signals of distance narrowband emitters with the nonuniform array, the ETAM algorithm is generalized, so that a non-overlap extended array (NOEA) algorithm is proposed. The NOEA algorithm need not overlapped correlating of array elements, and can estimate the phase correction factors (PCFs) through 2D MUSIC algorithm. By extending the array aperture, the NOEA algorithm will improve the resolving power of moving linear array effectively.In chapter 4, the passive synthetic aperture technologies for arbitrary geometry arrays are studied in two cases. In the first case, when the array moves with varying attitude, an array interpolation technology which can translate the outputs of an arbitrary geometries array into the outputs of a virtual linear array is utilized. Then the phase correction factors can be estimated via the outputs of the virtual linear array by the NOEA algorithm and then the passive synthetic aperture using arbitrary geometry array can be obtained. To meet the requirement of coherent signals processing and efficiency, the particle swarm optimization algorithm is used as the implement to realize the maximum likelihood estimation of 2D DOA for passive synthetic aperture. The proposed algorithm has extended the way of PCFs estimation, and can also generalize passive synthetic aperture technique to the application of arbitrary geometry arrays with varying attitude, noncontinuous wave signals and 2D DOA estimation. In the second case, when the attitude of moving array is not changed, another fast passive synthetic aperture algorithm using arbitrary geometry array based on array interpolation and ESPRIT technique is proposed. Then the interpolated array technique is applied again to construct a well-proportioned virtual array for spatial smoothing to overcome the singularity associated with coherent sources. Consequently the 2D DOA of closely spaced coherent sources can be estimated by the 2D MUSIC algorithm. Compared to the case one algorithm, the case two algorithm has the advantage of computational efficiency but need the stable attitude of moving array.In chapter 5, the temporal-spatial 2D array signal processing technologies are also studied in two cases. In the first case, to fulfill the requirement of high- resolution DOA estimation of moving array for coherent signals, the temporal-spatial 2D model of moving array and a temporal-spatial 2-D forward/ backward temporal smoothing technique are proposed. After that, the minimum array velocity for effectively resolving two coherent signals is deduced via geometrical analysis. Because the temporal-spatial processing and passive synthetic aperture technologies are similar in the using of kinematic information of array, this temporal-spatial processing of moving array can be considered as an implementation of passive synthetic aperture. In the second case, to reduce the computational load of temporal-spatial 2D estimation, a fast DOA estimation algorithm based on temporal-spatial 2D resolving is developed. The fast algorithm needs only one dimension search, but performs as well as temporal-spatial 2D processing.