LED communicator in various underwater environments

Demand for underwater communication in the 21st century has been growing. Underwater communication technologies are needed in many different environments; ranging from the underwater environments of the seas to small ponds. Underwater communication technologies used in these environments are used in a multitude of ways, such as, monitoring evolutionary changes, surveillance, underwater sensor networks, and military communication between ships and underwater-unmanned vehicles. Traditionally underwater communication has been accomplished using acoustic techniques that have data rates that can range from the kb/s and into the Mb/s. Interest in the use of optical communications has increased with the growing need for higher data rates, as well as, a secure way of transmitting it. Optical communications are capable of providing data speeds in the Gb/s due to a larger available bandwidth. Optical communications are also inherently more secure due to the directional nature of the transmission. That said, there are a number of challenges to optical communications, which include scattering, absorption, extinction, and optical turbulence in underwater environments. This paper presents the performance of an inexpensive LED communication system operating in various emulated underwater environments. Specifically, we propagated ASCII data through various underwater environments, and analyzed system performance under the effects of salinity level, temperature turbulence effects, mechanically generated turbulence, as well as the misalignment between the transmitter and receiver. Relevant performance metrics studied include bit error rates, power received, and channel data rates.