Abstract

Indian Beacon DGPS Systems Network

Ajay Seth

Abstract
Marine Beacons were extensively used for direction finding till early 1990. Marine group of Leica developed the first Beacon Modulator and Beacon Demodulator for transmitting the DGPS corrections via Maritime Beacons. The first two systems were installed in Sweden and Finland. In 1993 Director General of Lighthouses and Lightships (DGLL) requested Marine group to prepare a preliminary report for introducing DGPS in India using the Radio beacons used for direction finding application.

Based on practical experience and careful evaluation of future needs, DGLL prepared a specification for an advanced DGPS network covering entire Indian coastline and islands of Andaman and Nicobar and minicoy group by establishment of 22 DGPS stations. The specified network would meet all international standards, be simple to install, easy to operate, both remotely and locally, and would provide excellent accuracy and operational availability, even under adverse conditions. A tender was issued for the initial requirement of ten Broadcast Stations and a contract was awarded to Elcome Marine (Leica dealer in India). The contract included the procurement, installation and training on Leica New Generation Beacon DGPS Systems. These systems were commissioned in 1998-1999.

After careful evaluation, performance and coverage of these ten DGPS systems, DGLL has placed a further order for seven Beacon DGPS systems at the existing Beacon sites and two DGPS systems at new sites with an option for three additional systems. These systems were commissioned and are in operation now. DGLL has awarded the option of three more systems and these systems will be installed soon. After the commissioning of these three stations, Indian Beacon DGPS Network will have twenty two Stations seamlessly covering the entire Indian coastline.

Windows NT is used for system software, which takes full advantage of its multi-tasking capabilities. A Window user interface makes operation of this powerful system simple, intuitive, and easy to absorb. The reference receivers and integrity monitors meet the latest RSIM and RTCM message standards, are extremely rugged, and are designed for continuous operation.

Overall, the design provides a complete, turn-key solution, with continuous integrity monitoring, virtually no downtime, and which is easily installed, maintained, and operated. This new generation DGPS System and its capabilities are described, and the excellent field performance of the Indian DGPS Network is documented.

The paper also proposes the further expansion of Beacon DGPS network with the Central Monitoring Station. All the base stations and Central station can be connected via Wide Area Network (WAN). The WAN network and current beacon station locations can be used for adding the Automatic Identification System (AIS) Monitoring Stations at a later date.