Aerial remote sensing of underwater acoustic signal based on laser interference

Feature extraction and recognition of underwater targets has a wide range of needs whether in the military or civilian areas. Underwater target aerial remote sensing technique based on laser interference is a new technology which combined with laser and ultrasound, and is full of development prospects. Based on the basic mechanism by which the laser interference process is used to detect acoustic waves on the water surface, a set of experimental equipment to detect underwater acoustic signals with such methods is set up in an optical darkroom, achieving the real-time detection of underwater targets with acoustic frequencies ranging 300Hz–19kHz. To get the accurate underwater acoustic signal frequency, a method based on Hilbert-Huang Transform was proposed in this paper. The relative error of the frequency of underwater acoustic signal demodulated is less than 2% in general.