Direct Localization of Shortwave Emitters in Multipath Ionosphere Channel

The conventional techniques designed for localization of shortwave emitters are two-step methods. Since the internal constraint of the received data is ignored, the two-step methods are considered suboptimal. Besides, an extra procedure of data association is required for the localization of multiple emitters. To overcome the drawbacks mentioned above, methods which can directly determine the locations of emitters attract attention of the researchers. However, virtual height of reflection in an unknown ionosphere is hard to estimate, the relation between the location of emitter and the steering vector cannot be determined. In such scenario, the direct localization is no longer work. To overcome this limitation, we present an ionosphere multipath reflection model. In this work, a novel method is proposed to decouple angles. By taking advantages of the decoupled technique, the direct localization methods do not require multi-dimensional search caused by unknown ionosphere virtual heights, and can decrease the computational complexity. Simulation results verify the effectiveness of the proposed method.