Standard-C and Positioning

Abstract

Since the days of Sputnik, 1, Transit and Early Bird, satellite communications and navigation have followed separate development paths. Now with the development of the INMARSAT Standard-C and Enhanced Group Call systems the two will be drawn more closely together. Standard-C will provide a simple low cost satellite solution for ships to send and receive data and messages throughout the world in any weather 24 hours a day. For the mariner this will mark a significant advancement over existing conventional services. The Enhanced Group Call (EGC) system uses the basic Standard-C system architecture to broadcast Marine Safety Information (SafetyNET) and commercial calls (FleetNET) to defined geographic areas or groups of ships. The EGC system therefore brings the mariner an optimal way to automatically receive shore-to-ship distress alerts, routine weather forecasts and NAVAREA and storm warnings applicable to the area in which he is sailing. For the commercial user it offers a means to provide news, stock, commodity market and other business information to a selected group of recipients. In the future it may also provide the means for automatically updating data bases containing electronic charts, light lists, tide tables, hazardous cargo and other information currently carried in printed form. The ability to advise ships in near real-time of pertinent Marine Safety Information will be demonstrated during sea trials of the EGC system in the North Atlantic during 1987. A successful trial is expected to lead to IMO making an EGC receiver capability a part of the Global Maritime Distress and Safety System (GMDSS) carriage requirements which, together with 518 KHz NAVTEX, will enable the mariner to receive crucial Marine Safety Information automatically anywhere he sails. The Standard-C ship earth station (SES) will have the ability to transmit the vessel's position automatically when connected to an electronic positioning system, either at pre-assigned intervals or on demand when polled. The same capability may also be used to transmit meteorological observations as well as cargo and engine monitoring/performance data. Starting in 1987, INMARSAT will test and demonstrate position determination through its satellites by using ranging techniques. It is planned that some of these tests will be conducted using modified Standard-C SESs. Sea Trials of Standard-C will begin in the latter part of 1987 with commercial service from 1988. The multifunctional capabilities of this small, lightweight, low-cost SES with omnidirectional antenna are remarkable. Standard-C will therefore have a significant impact on navigation and communications practice and thinking by the marine community into the 21st Century.