A High Precision Direction-Finding Method Based on Multi-Baseline for Target Rescue

Target rescue is an important application in the Internet of Things (IoT), and the direction-finding (DF) is an essential technology for the target rescue. The DF technology based on the phase comparison method is widely used in target rescue. However, due to the phase ambiguity, the phase comparison method is difficult to meet the needs of high precision DF. The long and short baseline method can eliminate the phase ambiguity in a certain angle range, but it cannot accurately direction in all directions. In this article, we propose a high precision DF method based on the multi-baseline and multi-antenna for target rescue. Firstly, the performance of the proposed method in eliminating the inhomogeneity and azimuth ambiguity in single antenna pairs is analyzed theoretically. Then, a measurement system configured of a cycle array with eight antennas is presented to validate the practicability of the proposed method. Finally, the measurement system is verified by experiments conducted in both anechoic chamber and the out-field scenarios. The experiment results demonstrate that the error of the proposed DF method is within 2 degrees in the anechoic chamber and within 5 degrees in out-field. Therefore, the proposed multi-baseline and multi-antenna method can be used for high precision DF for the target rescue.