Abstract

Land Navigation using GPS - Preliminary Discussions


Swarna Sangeetha
Software Engineer
Maples ESM Technologies Pvt. Ltd.,
Email: sravindra_babu@hotmail.com


Though the art of navigation existed since the medieval times, nevertheless, it has assumed significant proportions with the advent of sophisticated technologies such as GPS (Global Positioning System). With a constellation of 24 satellites, the GPS satellites transmit coded signals to all the users around the earth. The receiver decodes the ‘navigation data’ from these signals and computes the receiver’s 3-dimensional position and velocity. In these modern days, several value-added services, such as emergency services, tracking of children, location based billing, etc., can be imparted if one’s location is known. Therefore, the determination of position of a person/vehicle with reasonable accuracy has become utmost important. Several land-based applications require position information accurately for effective utilisation of services; some of them are: car navigation, tracking of trains, mobile positioning etc. This paper focuses on the tracking of a train using a GPS receiver in the context of Indian Railways.

A GPS receiver is mounted on a train to determine its position and velocity continuously. This information is used by the railway authorities to optimally assign the tracks, efficient scheduling of the routes, re-routing of the trains in the case of tracks obstruction either due to accidents or natural calamities, collision detection. The GPS receiver on board the trains continuously transmit its location details (position, velocity) via a radio communication link to the Central Management Server (CMS). A GIS (Geographic Information System) at the CMS monitors the location of the various trains and optimally takes a decision in effective route management. In addition, the GPS receivers also provide information to the on-board passengers by giving them information such as: time elapsed since the previous station, expected time of arrival to the next station, current position, speed and time, etc. The passengers equipped with this information can prepare themselves for boarding, alighting etc. upfront. This paper provides a comprehensive overview of the utilisation of the GPS information onboard the train with examples.