Methods and Apparatus for Free-Space Undersea Communications

Underwater communication has been a field fraught with challenges due to the novel environment that water presents. Traditional mediums like electromagnetic waves have a limited range underwater, and the need for wired solutions makes mobility a significant issue. These factors necessitate a technology that can efficiently transmit data wirelessly under these circumstances. Current approaches predominantly work on a fixed wavelength, have limited bandwidth, and struggle to adapt to environmental changes in real time. They also do not account for the unpredictable obstructions that are common in underwater channels, often leading to data loss or interruption in transmission. These limitations impede the efficiency of underwater data transmission in dynamic environments and changing water conditions.

Technology Description

The multi-rate, burst-mode, photon-counting receiver, capable of data rates up to 10.416 Mb/s, is equipped for underwater communication. Its robust performance displays a maximum link loss of 97.1 dB, allowing it to communicate over distances up to 450 meters depending upon the light wavelength utilized. With soft-decision forward error correction, it affords multiple code rates for error-free performance. The burst-mode receiver architecture is specifically designed to endure unpredictable channel obstructions. The power of the receiver lies in its ability to adapt to ever-fluctuating conditions. It can detect the data rate on-the-fly and adapt to changes in signal and background light. Furthermore, it modifies its phase alignment and channel estimates every frame. It allows for rapid amendments necessitated by swift changes in water quality and motion between transmitter and receiver, setting it apart from conventional technologies.