Abstract: A wrist unit is provided for allowing the diver to view the breathing parameters that are determined. The breathing parameters are determined by a tank processor via sensors that are disposed on the breathing tank of the diver. These are transmitted to the display unit on the wrist of the diver via a wireless communication link. An inertia switch is provided in the wrist unit, the wrist unit having a watertight housing. The inertia switch is responsive to impacts in the form of tapping on the housing or of rotation of the wrist. When the wrist is rotated, the inertia switch will generate impulses that can be counted and, after a predetermined number, generate a control signal. The control signal controls the on/off function of the wrist unit and also allows switching between alternate displays.

Abstract: A multi-gas blending system for a diving profile is provided with three separate tanks, each having a different gas mix contained therein. The first tank, the primary tank, has a mix that is designed to be O.sub.2 rich for descending from the surface to a predetermined diving depth. At the predetermined diving depth, a switch is made by the diver and the system detects this switch. Prior to the switch, breathing parameters are calculated based upon the gas mix in the primary tank. Once the switch is detected, the calculation is performed on the mix in the second tank. This calculation continues until a predetermined amount of time has elapsed while the diver is on the secondary tank and the diver has begun an ascent and has passed a predefined depth. Once these two conditions occur, this is defined as a switch to a third gas mix, at which time the dive computer begins calculating the breathing parameters based upon a gas mix in a third tank. This is a decompression mixture.

Abstract: An advanced dive computer for use by a user of a self-contained underwater breathing apparatus that can communicate with a conventional personal computer through a digital computer interface to allow the user to customize the dive computer. The dive computer also calculates and stores a variety of dive parameters that the user can access with a conventional personal computer. Moreover, the dive computer automatically calibrates its depth calculations in accordance with the salinity of the water into which it is submerged and is sealed in a secure watertight case with as few case-penetrations a possible.