The complete Naiad underwater positioning system is a Diving Navigation System, providing divers with an automatic display of direction, and distance to a reference point.
The Naiad system is best characterized by its simplicity. It is small enough to be worn as a wrist watch, and like a watch, once set, operates automatically.

Characteristics
The Naiad is composed of two modules:
-The Naiad TX transmitter, which is submerged at a point of reference (in general under the dive boat attached to the drop line)
-The Naiad RX receiver, which is worn by the diver and displays the diving information, more specifically, the direction and the distance to the transmitter

The Naiad operates according to the principle of a sonar:
-The Naiad TX transmitter sends out ultra-sonic acoustic pulses, at a designated frequency, which radiate in all directions.
-The diver’s Naiad RX receiver captures the pulses, it then processes them, and displays the distance and direction to the Naiad TX transmitter. The receiver is passive equipment and does not transmit any signal.

OPERATING MODES The Naiad sonar can operates in two different modes:
-The Navigation Mode is when the RX receiver permanently displays the direction, and distance from the starting point.
-The Recall Mode warns the diver of a situation of emergency or danger requiring his or her immediate ascent and return to the boat. It is initiated on the TX transmitter and is triggered by the person responsible for the dive, aboard the boat.