The Indian space agency plans to launch its fourth regional navigation satellite by March-end after replacing a faulty transmitter, a senior official said on Tuesday.
 
 "We are planning to launch the satellite by the end of this month. The replacement transmitter is getting ready and will be brought from our centre in Bangalore," M.Y.S. Prasad, director, Satish Dhawan Space Centre (SDSC), told IANS on the phone from Sriharikota, around 80 km from Chennai.
 
 He said the faulty transmitter in the satellite will be replaced at SDSC.
 
 The 1,425 kg satellite — Indian Regional Navigation Satellite System (IRNSS-1D) — was supposed to be launched on March 9 in the evening by an Indian rocket called Polar Satellite Launch Vehicle (PSLV-XL).
 
 The Indian Space Research Organisation (ISRO) on March 4, however, deferred the launch after it found one of the telemetry transmitters in the IRNSS-1D not working properly.
 
 It is the first time in ISRO's history that a satellite has to be dismounted from a rocket due to a problem in it.
 
 Prior to this incident satellites have been dismounted from a rocket but due to some other problem.
 
 India has so far launched three regional navigational satellites as part of a constellation of seven satellites to provide accurate position information service to users across the country and the region, extending up to an area of 1,500 km.
 
 Though the full system comprises nine satellites – seven in orbit and two on the ground as stand-by – the navigation services could be made operational with four satellites, ISRO officials had said.
 
 Each satellite costs around Rs.150 crore and the PSLV-XL version rocket would cost around Rs.130 crore. The seven rockets would involve an outlay of around Rs.910 crore.
 
 The entire IRNSS constellation of seven satellites is planned to be completed by 2015.
 
 The first satellite IRNSS-1A was launched in July 2013, the second IRNSS-1B in April 2014 and the third on October 16, 2014.
 
 Once the regional navigation system is in place, India need not be dependent on other platforms.