Indian Regional Navigational Satellite System
- Paper number
IAC-07-B2.1.01
- Author
Dr. Surendra Pal, Indian Space Research Organisation (ISRO), India
- Coauthor
Mr. A.S. Ganeshan, Indian Space Research Organisation (ISRO), India
- Coauthor
Mr. KNS Rao, Indian Space Research Organisation (ISRO), ISAC, India
- Coauthor
Mr. L. Mruthyunjaya, Indian Space Research Organisation (ISRO), ISAC, India
- Year
2007
- Abstract
ISRO is establishing an Indian Regional Navigation Satellite System (IRNSS) to provide location information to various users over the Indian land mass. The objective of IRNSS Project is to implement an independent and indigenously developed Regional Satellite based Navigation System for national applications. The IRNSS system consists of Space, Ground and User elements. The IRNSS is being designed to provide position accuracy of 10m in a major portion of the coverage. IRNSS system is expected to provide an accurate real time position, velocity and time for users on a variety of platforms with a 24 x 7 service availability under all weather.
This paper is intended to present the objectives, the constellation studies conducted, the onboard and the ground configuration, user segment and related issues.
IRNSS Constellation
Extensive constellation studies were conducted to ensure a minimum of 4 satellite continuous visibility to users to meet the position accuracy required over the Indian land mass. Based on the various constellation studies the minimum number of satellites required for IRNSS constellation was worked out to be 7. Three satellites will be located in Geo Synchronous Orbit (GSO) at 34°, 83° and 132° East and the remaining four will be located in Non- Geo Synchronous Orbit (NGSO)with an inclination of 29o and longitude crossing at 55° and 111° East in two different planes. A snap shot of the satellite locations together with the 99
IRNSS Architecture The IRNSS system mainly consists of: Ground Segment,Space Segment and User Segment.
Ground Segment Ground Segment is responsible for the maintenance and operation of the IRNSS constellation. The Ground segment contains a whole complement of the elements required for a basic constellation and mainly comprises of: Master Control Centers for Spacecraft control and Navigation, IRNSS Tracking and Integrity Monitoring Stations,CDMA Ranging stations, Up-linking and Telemetry stations, Communication Links and Network timing Centre.
Space Segment The IRNSS satellites carry Navigation Payload in redundant configuration. A separate C-band transponder for precise CDMA ranging is included in the payload configuration. The important functions of the IRNSS payload are: Transmission of navigational timing information in L5 band,Transmission of navigation, timing information in S-band,Generation of navigation data on-board,CDMA ranging transponder for precise ranging.
The Navigation payload will have the following subsystem: Navigation Signal Generation Unit (NSGU), Atomic clock unit, comprising of Rubidium Atomic Clocks, Clock management and control unit,Frequency generation unit,Modulation unit,High power amplifier unit, Power combining unit and Navigation antenna
The IRNSS spacecraft are dedicated for navigation services and they are configured to be of a class that can be launched by the Indian Launcher PSLV. The design incorporates most of the proven subsystems available indigenously tailoring it specifically for the navigation.
User Segment Specially designed receiver and antenna are needed to receive IRNSS signals. Receivers capable of receiving multi constellation signals inclusive of GPS , GLONASS, IRNSS etc are also envisaged . It is planned to broadcast the time difference between the IRNSS time and the time of the other constellations to enable the users to take advantage of the signals available to them.
- Abstract document