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Ocean Reef Gsm DC Dat Transceiver

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Ocean Reef Gsm DC Dat Transceiver


Ocean Reef Gsm DC Dat Transceiver

In the era of mobile telephones, underwater communication represents an essential evolution not only for safety, but also to improve and widen the operating conditions. To communicate means to exchange information and emotions in real time. It means to make the dive easier, more comfortable and amusing. It means to open new horizons to the underwater activity. If you loose sight of your dive buddies or the boat, you are completely isolated, unless you have an appropriate transceiver. Ocean REEF proposes an underwater communication standard, which is solid, sturdy, and easy to use for recreational diving, research, training, commercial or scientific use. It consists of a GSM, (Global Submarine Messenger) ultrasound transceivers/ receiver, a M101A receiver unit and a M105 surface unit.


The GSM DC underwater transceiver unit incorporates the latest innovation in underwater ultrasonic 2-Way Radio communication; featuring a digital driver for vocal message equalization, an automatic system for activating (DAT) transmission and a double transceiver channel. The GSM DC can be used on the Neptune II Full Face Mask, preferred, or on other Full Face Masks equipped with a standard DIN female connection. Underwater communication technology is accomplished with ultrasound and is started by a PTT, Push To Talk, microphone button, which must be pressed to activate transmission and released to receive. The standard frequency (channel one) is the same for all units, so it is possible to talk directly with any other GSM DC™, GSM DAT™, GSM, M-101A receive units, surface M-105 Digital units and all previous surface systems (M103 - M104 - M105). The GSM DC sound qualities depend both on the D-Mic microphone and the microprocessor (DSP), which takes the digitized vocal message and filters out unwanted noise caused by exhaust air bubbles or vibrations of the mask, particularly the visor.

More Details

The GSM DC™ has two buttons.

  • The A button activates the manual mode transmission. Pressing the button you are able to transmit, releasing the button you may receive.
    The B button activates and de-activates the automatic transmission mode: DAT™
  • Pressing the button A and B it is possible the change the frequency channel.
  • The unit is equipped with 2 transceiver channels, and at any time you change the channel you will ear a recorded message informing you of what channel you are activating (channel one - channel two)
  • The double channel allows two different diver groups to operate in the same area, limiting the interference between them. The channel 2 improves, if necessary the operations range without reducing the battery autonomy.
  • The GSM DC™ uses standard alkaline 9 VDC batteries, has gold plated contacts for the 9 V alkaline battery and a "low battery" warning signal that beeps every 30 seconds.
  • The GSM DC™ system uses the exclusive "D-Mic" - a special dynamic microphone for underwater use with its high acoustic qualities.
  • The D-Mic housing has a hydrophonic membrane, which is permeable to air, but prevents water from passing through into the electronics. The membrane limits attenuation of the vocal signal thanks to its reduced thickness. The permeable characteristics of the membrane keep the internal pressure equalized at the same level as the external ambient pressure so that the microphone can practically be used at any depth. The D-Mic is easily installed onto the transmission button contacts, and is also compatible with all previous GSM versions by slightly altering the transmission button contacts, which can be performed by our Service Centers.
  • When we talk inside a Full Face Mask, a series of reflections and vibrations are generated which may be called "distorted frequencies."
  • 1. High frequencies caused by mask visor vibrations
  • 2. Low frequencies caused by the noise from air bubbles
  • These "distorted frequencies", if they are not removed, will by amplified and transmitted to the receiver unit and will generate a low intelligibility in the receiver unit. With our (DSP) microprocessor, communication is loud and clear.
  • The patented NACS is an adjustable support for the GSM DCTM or M101A receiver that is installed on the Neptune II mask by the two supports on the left hand side of the visor, the same supports as used to install the protective shield. With the NACS, the GSM DC or M101A does not hang on the strap of the mask, avoiding excessive unwanted compression against the ear. This also allows the strap to slide through the buckle easier without twisting because of the weight of the GSM. Now the strap can stay loose when the mask is being put on and the GSM stays out of the way. NACS is also fitted with an adjustment for tilting and setting the distance between the communicator and visor to get the most comfortable and satisfactory position against the user's ear. 
  • DAT (Digital Activation Transmission) It is an Ocean REEF worldwide innovation in underwater communications for diving. With the DAT system it is possible to transmit without keeping the microphone button pressed down. All that is required to activate transmission is to press and release the button quickly, at which point, a series of impulses are sent out keeping the GSM transceiver automatically on for 30 seconds without having to keep the button pressed down. Then the unit will return to the receiving mode for 20 seconds with a series of impulses in a different tone from the first.This cycle goes on until the button is pressed again for at least 1 second to return to the manual mode. DAT is particularly usefull when it is necessary to have both hands free while transmitting, making diving far more confortable and safer. Another benefit of the DAT system is in case of an emergency, when activated, it will emit a sequence of impulses every 30-20-30 seconds, ... that can be received at a great distance so that search & rescue workers can more easily make contact with the diver.

Shipping Details

Estimate Shipping Weight: 4.00 Pounds
Weight Disclaimer:  *Weight may vary based on size.