Bangalore: Indian Space Research Organisation (ISRO) is in the final stages of signing a major contract with a US company, Raytheon, it was announced at the Indo-US Space Meet here today (June 23, 2004).

When signed in the next few days, the company will help ISRO install the system that will allow aircraft to use the constellation of GPS satellites of the US.

Using special receivers, the GPS signals allow one to get a positional fix. But the signals must be augmented to provide the accuracy needed for aircraft navigation and landing.

ISRO in collaboration with Airports Authority of India (AAI) has come up with a system to augment the signals from GPS satellites called "Gagan" (GPS aided geo-augmented navigation).

It involves setting up ground-based GPS reference stations and a navigational payload in a geo-stationary satellite.

Gagan Project Director K N Suryanarayana Rao said that Raytheon after getting the contract would set up the entire ground systems and the mission control facility.

The navigational payload is being developed by ISRO. It will be put in a G-SAT satellite to be launched in 2006, Rao said.

After an experimental phase for a year, the payload will be operational by 2008.