Multiband imaging and linear unmixing of optical fiber intrusion signal

Feature extraction of the optical fiber intrusion signal is one of the most basic problems in the optical fiber pre-warning system (OFPS). This paper proposes a spectrum analysis method in the OFPS that adopts the time-frequency analysis technique to realize multiband imaging of the intrusion signal at first. Subsequently, the characteristic spectrum of the intrusion signal can be obtained as the intrusion feature from the imaging results. Since the practical intrusion spectrum is usually a mixture of multiple intrusion types, in order to extract the spectrum corresponding to each intrusion type, the mixed spectrum is characterized by a linear mixing mode. Then, we exploit the nonnegative matrix factorization (NMF) in the mixture analysis. Moreover, we add physical constraints to the NMF and solve it by gradient descent algorithm. Finally, we extract the characteristic spectrums from the mixed spectrum resulting to the spectrum unmixing. The real data experiments verify the effectiveness of this method.