The basic components of SHARKNET are: a GPS receiver, a depth/temperature sensor, an accelerometer, a cell phone module, a processor, a LED and a Bluetooth module.
When the user is at the surface, the GPS receiver monitors the geographical position and the phone module answers to any incoming text message from somebody (whom we left our number to) that is asking for our location.
When the dive begins, both GPS and cell phone signals are lost. The processor then turns off the phone and stores in memory the last GPS position fix as the starting point of our dive.
From this time on, every five seconds the processor stores the diver’s depth, temperature and attitude (standing/horizontal/upside down) as measured by the accelerometer. Upon resurfacing, SHARKNET reacquires a GPS fix, stores it as the final diving location and (with its phone module) automatically transmits all data to the SHARKNET server.
The SHARKNET server hosts a database with the information of each user. When the server receives a data file, it associates it to the user owning the device that transmitted the data. This way the user has his logbook always update.
In case of emergency, when the user double taps SHARKNET, the accelerometer recognizes the double tap and notifies the processor. This makes the LED quickly flash and, if at the surface, the phone module transmits an alarm message to the server, that forwards it to all chosen addressees through text messages, phone calls or emails.
If the emergency is activated while underwater, the processor stores the alarm in the data file describing the dive and, once at the surface, it transmits the file to the server, that memorizes data into the user’s space and forwards the alarm to all addressees.