Diver Emergency Through Water Communications System

Emergency Through Water Communications is an essential element for any saturation diving operation. Should wired communication links be lost because of severed umbilical then it is vital that clear and reliable communications can be made to the dive bell.

Imenco Nautronix design and manufacture a range of diver emergency acoustic communications units which can provide clear, long range speech capability through water. A system comprises of a surface unit and a bell unit, each with full hemispherical beam pattern and battery back-up.

The ETWC system primary use is underwater voice communications between a surface vessel and diving bell in emergency situations. This system can be equally well utilised in a manned submersible for communications to a mother ship. Clear and reliable half-duplex voice communications is achievable at depths of 610m (2000 feet).

The system is designed and proven to operate in a State 6 sea, equivalent to 22-knot wind with 3m (10 feet) waves. These products output 20 watts of acoustic power, thus providing long range usage even in high noise conditions ensuring that the surface units will clearly receive speech from the diving bell.

3136C ETWC Surface Unit

The Surface Unit 3136B is a 4U high standard 19” rack mounted unit powered by external 24v power supply. It is capable of transmitting 183.7-dB ref. 1 micro Pascal at 1 metre + 3dB (20 watts) acoustic power with an approximate bandwidth of 3 kHz. Operating time, based on a 10% transmitting, 90% listening cycle, is in the order of 15 hours.

3140 ETWC System Bell Components

The Bell Unit, Model 3133B, is designed to be operated in a diving bell atmosphere up to a depth of 610m (2000 feet) and requires a 24 Vdc power source. It is capable of transmitting a 183.7 dB ref. 1 micro Pascal at 1 metre + 3 dB (20 watts) of acoustic power. Operating time is dependent on the power supply available; in the receiving mode, the supply requirements are 0.04 Amperes, while in the transmitting mode it increases to between 1 and 3 Amperes. Reverse polarity protection is provided.

The electronics pod and battery pack are mounted onto the outside of the bell which removes possible danger to divers enclosed in a confined space. The emergency through water comms box, fist mic and speaker are the only units located inside the bell, with activation of the through water communications made by the two position switch on the E.T.W. comms box and the levels adjusted from the volume knob.