Although, acoustic techniques are currently in vogue technologies for detection and tracking of submerged bodies like submarine and autonomous underwater vehicles, the advent of silent submarines and the ensuing technologies resulting in the reduction of acoustic signatures is making naval surveillance very difficult, especially in shallow water environments. Some of the non-acoustic techniques such as Magnetic Anomaly Detection, LIDAR, bioluminescence detection, etc. were earlier thought to be promising, however subsequent research showed their inherent limitations which restrict their use for detection over a wide area and also from a large distance.
Using Satellite and Small-scale UAVs (Drone-acharya) is image processing and Sensitive monitoring of surface area for various objectives related to Surveillance, security, Environmental, Disaster, Search and Rescue etc.
The remote sensing satellite systems will detect targets from Space, interprets hydrodynamic patterns that are generated by targets. The optical and radar images of ship wakes can be interpreted in terms of the classical work of Kelvin and Bragg, respectively.