A New International Position Reporting Service for Maritime and Land Mobile Users

A. Ekman

Abstract:	INMARSAT's Standard-C is a mobile satellite communications system which provides medium bit rate (600 biVs), two-way data communications using small mobile terminals with omni-­directional antennas. In addition to the message protocol which is used to transfer data of any length, other protocols for specialized applications, such as Distress Alert and Data Reporting, have been included. Based on the Data Reporting Protocol, optimized for short messages, a Position Reporting Service has been defined. This service, which is intended for land mobile and maritime users, provides cost effective transfer of Position Reports, with or without ancillary data, from a mobile to a base station, which is typically located at the head office of a trucking or shipping company, or at a government authority, e.g. one that supervises transportation of hazardous goods. Position is determined by a navigation sensor (GPS, GLONASS, Loran-C. Transit, Omega, dead reckoning, or combinations thereof) which connects to the mobile terminal via a standard interface. In the future integrated navigation and communication equipment is anticipated. The ancillary data may be an encoded text message (i.e. a text message that is represented by a unique pre-defined code), or data from a sensor in the vehicle (engine, driver or cargo status etc). The position reports are generated by the mobile terminals and sent to one of INMARSAT's Coast Earth Stations (CESs) using the Data Reporting protocol. A report consists of up to three Data Report packets, each 15 bytes long. A detailed packet format has been specified. The terminals can be set up to transmit Position Reports on a regular basis, or in response to a poll from the base station. At the CES the reports are stored for subsequent retrieval by the base station. The base station receives, processes and displays the reports using a desk top computer and an Automatic Vehicle Location (AVL) software package, which allows display of vessel or vehicle positions on maps and includes a number of database functions. It can also be connected to more advanced Fleet Management Systems. The base station can request the terminals to transmit a position report by sending a poll (either to individual mobiles or to a group of mobiles) using the polling protocol. The poll can also include a text message. This paper gives a description of the Position Reporting Service and explains the position reporting format. Information on how user specific data can be included in the reports is given, and the integration of the Position Reporting system with fleet management systems is discussed. Automatic Vehicle location software which has been developed for the pre-operational Standard-C system is also described.
Published in:	Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989) September 27 - 29, 1989 The Broadmoor Hotel Colorado Spring, CO
Pages:	133 - 137
Cite this article:	Ekman, A., "A New International Position Reporting Service for Maritime and Land Mobile Users," Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989), Colorado Spring, CO, September 1989, pp. 133-137.
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