Underwater Acoustic Imaging: One-bit Digitisation

摘要: In underwater acoustic imaging (UAI), the combination of a two-dimensional (2-D) array and replicate correlation can produce 3-D images, typically objects at range 2 m. A system already developed achieves high data acquisition rate needed through one-bit sampling (sensing only sign received signal). Noise added before avoids production ‘ghosts’ in image. By simulation mathematical analysis, effects noise are studied for chirp signal, with restriction so far to 1-D images (image amplitude versus range). Conditions given avoidance ghosts minimisation ‘image noise’— image due noise. model is proposed, which corroborated by tests carried out date. general formula rootmean-square obtained. It has previously been suggested that filtering signal after would improve However, it shown unnecessary indeed makes worse. strong target suppress evidence weak because, when strength return raised, essentially must be raised avoid ‘ghosts.’ formula, giving ratio strengths such 50% probability detection,