The rocket is scheduled to take off at around 4 pm from the spaceport at Sriharikota in Andhra Pradesh around 80 km from here.
Till date Isro has launched five regional navigational satellites (IRNSS-1A, 1B, 1C and ID) 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 of 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 earlier.
Each satellite costs around Rs 150 crore and the PSLV-XL version rocket costs 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 in 2016 itself.
The first satellite IRNSS-1A was launched in July 2013, the second IRNSS-1B in April 2014, the third on October 2014 and the fourth on March 2015.