What are the main systems in the GMDSS?

MCA Oral Exam Questions

(1) COSPAS-SARSAT, an international satellite-based search-and-rescue system which uses polar-orbiting satellites to transmit to rescue co-ordination centres a vessel's identification and accurate location from anywhere in the world; 

(2) Inmarsat (the International Mobile Satellite Organization), which provides distress message facilities on the L band and transmits the SafetyNET service, a satellite-based world-wide maritime safety information broadcast of high seas weather warnings: (3) Digital Selective Calling (DSC on VHF, MFand HF radio channels, which speeds distress and general radiotelephone calls to and from shore and other ships: and (4) NAVTEX, an international automated system for distributing maritime navigational warnings, weather information and warnings, and search-and-rescue information to ships automatically.