Abstract: An apparatus is described which uses directly modulated InGaN Light-Emitting Diodes (LEDs) or InGaN lasers as the transmitters for an underwater data-communication device. The receiver uses automatic gain control to facilitate performance of the apparatus over a wide-range of distances and water turbidities.

Abstract: A method of determining battery performance information indicative of a performance of a battery in a device is disclosed, the method including: receiving environmental condition information indicative of environmental conditions of the device during a usage period; receiving operating parameter information indicative of one or more operating parameters of the battery during the usage period; and determining the battery performance information based at least in part on: the environmental condition information, the operating parameter information, and a performance model corresponding to the battery.