Near-Field Multisource Localization and Signal Enhancement With ASP-Assisted DAS

Since the superiorities of large-scale and distributed measurement, the fiber-optic distributed acoustic sensing (DAS) technique can collect plenty of distributed acoustic signals. Therefore, it has been gradually applied to perimeter security applications recently. However, the multisource near-field 2-D and 3-D localization and signal enhancement without aliasing noise for large-scale DAS has not been achieved yet, which are highly necessary for large-scale perimeter security applications. So, in this work, the DAS assisted with near-field array signal processing (ASP) is further developed and demonstrated, in which the near-field multiple signal classification (NF-MUSIC) algorithm is developed to achieve the near-field multisource localization. Then, based on the obtained target source position, the minimum variance distortionless response beamformer (MVDR-BF) is further proposed to enhance target signal in DAS, including multisource aliasing noise. In lab test, the maximum localization error no more than 0.03 m and 0.3 degrees is demonstrated by using the proposed ASP-assisted DAS. And the acoustic target tracking is also achieved in underwater field test. Then, the signal to noise ratio (SNR) of the target source in lab and underwater test is averagely enhanced about 9.7 and 16.8 dB by, respectively, using 5 and 20 channels. To the best of our knowledge, it is the first time to achieve the near-field multisource localization and signal enhancement for fiber-optic DAS. Substantially, this work has been greatly verified the proposed scheme that can further expand and promote the large-scale DAS practical applications, including the low-altitude and underwater multitarget detection, localization, and recognition.