Radiation Source Passive Location In Complex Electromagnetic Environment

With the continuous development of modern wireless communication technology, an increasing amount of devices have been emitting electromagnetic signals by stronger radiation power and in wider bandwidth, and thus sources of electromagnetic radiation have been multiplying in numbers and types. Electromagnetic waves propagation through direct, reflection and diffraction may disperse signals in aspects of amplitude, phase and delay. Consequently, it is hard to guarantee the positioning accuracy, by adopting varieties of traditional passive location strategies based on the line-of-sight propagation.To solve the above problems, research has been carried on in the following aspects:(1) According to wild terrain and different types of transceivers, the simulation for radio propagation in complex electromagnetic environment is set up, to get useful information on received signal power, Time Difference of Arrival (TDOA), and Direction of Arrival (DOA).(2) By innovatively applying particle swarm algorithm to TDOA passive location strategy, the lack of a good initial value and the complexity of computation in traditional strategies can be avoided, and thus the robustness and versatility of traditional methods can be improved. Additionally, concerning the particular scenario of passive location, the information on Direction of Arrival has been adopted in solution procedure to rule out the possibility of local optimal solution. Specifically, with the utilization of directional information, initial search area has decreased by90%, and positioning efficiency has increased by41%.(3) Instead of ignoring or weakening the impacts of multipath and Non Line of Sight (NLOS) on monitoring data, the effect of multipath propagation has been taken into account, and the reverse ray tracing algorithm has been used for tracing back to the source of radiation. In one embodiment, positioning errors are mainly distributed between20and30meters under the condition of severe multipath interference. This method, proved good performance by experimental results, provides another new solution for the future study.