India is expected to have its own satellite navigation system, with the launch of three more satellites before the end of this year, said the Indian space agency's chief on Monday.

Indian Space Research Organisation (ISRO) chairman K.Radhakrishnan told IANS that Indian communication satellite INSAT-3E has been decommissioned couple of days ago and the users are being migrated to other satellites.

"We will be receiving the signals from our navigation satellite system by the end of this year. We will be launching three more navigational satellites before the end of this year," Radhakrishnan said over phone from Bangalore.

The ISRO will be launching the second navigational satellite badged Indian Regional Navigation Satellite System-1B (IRNSS-1B) April 4 evening at 5.14 p.m.

The 1,432 kg satellite will be carried by Indian rocket Polar Satellite Launch Vehicle (PSLV).

According to Radhakrishnan, though the IRNSS is a seven satellite system, it could be made operational with four satellites.

The two more navigation satellites will be launched during the second half of 2014.

Prior to that, ISRO will be launching the French satellite SPOT-7 and four other foreign satellites in a PSLV rocket and also test its heavier rocket - the Geosynchronous Satellite Launch Vehicle (GSLV) Mark III version, said Radhakrishnan.

The IRNSS-1B satellite with a design life span of 10 years will be part of the seven-satellite Indian regional navigational system. The first navigational satellite IRNSS-1A was launched in July 2013.

The navigational system, developed by India, is designed to provide accurate position information service to users within the country and up to 1,500 km from the nation's boundary line.

The system is similar to the global positioning system of the US, Glonass of Russia, Galileo of Europe, China's Beidou or the Japanese Quasi Zenith Satellite System.

The system will be used for terrestrial, aerial and marine navigation, disaster management, vehicle tracking and fleet management, integration with mobile phones, mapping and geodetic data capture and others.

While the ISRO is silent on the navigation system's strategic application, it is clear that the IRNSS will be used for defence purposes as well.

According to the ISRO, the IRNSS-IB has been realised within seven months of the launch of the IRNSS-1A.

Satish Dhawan Space Centre (SDSC)-SHAR director M.Y.S.Prasad told IANS: "Even if a navigation system has more than four satellites, the final precise data is picked from four satellites."

Meanwhile Indian space agency officials are getting ready for the 58.5 hour launch countdown slated to begin April 2 around 6.45 a.m.

"Normally 53 hour countdown is sufficient. But we have decided to an extended countdown so that some break time could be given for the officials," Prasad said.

On the issue of INSAT-3E satellite, Radhakrishnan said the satellite was launched in 2003 and its lifespan has come to an end.

"Users are being migrated to other satellites," he said.