GMDSS radiocommunication functions
Only qualified radio personnel should operate equipment for GMDSS purposes. GMDSS equipped ships are required to be able to do the following wherever they operate:
· transmit ship-to-shore distress alerts by two independent means;
· receive shore-to-ship alerts (usually relayed by RCCs);
· transmit and receive:
· ship-to-ship alerts
· SAR co-ordinating communications
• on-scene communications
· locating signals
· maritime safety information
· routine or general communications to and from shore
· bridge-to-bridge communications.
GMDSS equipment
Ships operating GMDSS are equipped according to carriage requirements that relate to trading areas Areas A 1, A2, A3 and A4 as stipulated in SOLAS. All ships operating GMDSS can be expected to have at least the following equipment:
· VHF radiotelephone (Channels 6, 13 and 16):
· Channel 6 may be used ship-to-ship for SAR operations
· Channel 13 is used for safety of navigation ship-to-ship
· Channel 16 is used for distress and urgency traffic, and may be used by aircraft for safety purposes;
· VHF DSC (Channel 70) transmitter and watch receiver:
·Digital selective calling (DSC) is used for calling and replying, and for transmitting, acknowledging and relaying distress alerts. It allows a specific station to be Contacted and made aware that the calling station wishes to communicate with it, and to indicate how to reply, or which station to listen to for subsequent distress traffic. Calls can also be addressed to all ships or all stations;
· Search and rescue transponder (SART) used for providing homing signals from survival craft for detection by 9 GHz radar;
