The GMDSS system refers to the maritime radio communication system proposed and implemented by the International Maritime Organization (MO) for maritime distress, safety and daily communications. It is composed of the International Mobile Satellite Communication System, the Low Polar Orbit Search and Rescue Satellite System and the Very High Frequency(VHF), Medium/High Frequency (MF/HF)Ground Frequency Communication System, etc., with distress warning, search and rescue coordination communication, rescue on-site communication, Maritime safety information broadcast, position finding, daily communication, and bridge-to-bridge safety avoidance communication functions.