| Popis: |
Direction-of-Arrival (DOA) estimation and tracking with antenna arrays is a central topic of signal processing for decades due to its application to many walks of life. By collecting and processing target-originated signals on a passive receiving antenna array, multiple targets in the field will be detected and estimated in terms of their directions with respect to the receiving antenna array. If the targets are moving, their directions will be estimated and tracked as the targets move across the observation field. This dissertation addresses issues of interference and noise suppressing, wideband sources, multipath environment and computational complexity in DOA estimation and tracking. Several algorithms for DOA estimation or DOA tracking are developed. All of the algorithms are signal selective, that is, only the directions of the Signals Of Interest (SOI) will be detected or tracked. First, two signal selective DOA estimation algorithms (Improved Cyclic MUSIC, Improved Conjugate Cyclic MUSIC) are developed for narrowband signals. Then, based on these methods, two new algorithms (Averaged Cyclic MUSIC, Extended Wideband Cyclic MUSIC) which are able to deal with wideband cyclostationary signals are proposed. Then, to deal with the multipath problem, a method applying Spatial Smoothing (SS) technique to the Averaged Cyclic MUSIC algorithm is proposed. But SS results in a smaller effective array aperture, thus DOAs of fewer sources could be detected and the angle resolution is reduced. Therefore, an instantaneous DOA estimation method is proposed to simultaneously solve the wideband and multipath problems without using SS. After the directions for all the paths from multipath propagation are being detected, it is useful to assign the detected paths to their corresponding sources. Therefore, a path-source association algorithm for this purpose is developed. Finally the tracking problem is addressed. A new signal selective DOA tracking algorithm is presented for moving sources emitting narrowband or wideband cyclostationary signals. Computer simulations for all the algorithms are carried out to illustrate the effectiveness of these algorithms. |
