History

The predecessors for satellite navigation can be identified from the non-satellite era. Ground-based LORAN (LOng-RAnge Navigation) and Omega systems were used for terrestrial long-wave radio transmitters instead of satellites. The Russian system on lines of the LORAN is the Chayka. The LORAN system became operational in 1958 and was extensively used by the maritime community. The LORAN-C system came to be used for aerial navigation quite widely and during trials in 1963.1 It had its limitations in respect of some aviation requirements particularly with regard to precision approaches.[194] [195] This system also served as a backup for the US global positioning system (GPS). This system was ceased to be used from October 1,2010.

OMEGA was another navigation system developed by the USA with six partner nations for the purposes of military aviation. It was approved for development in 1968 and became operational in 1971 and had 6 km accuracy when fixing a position. With the success of GPS, its usage declined, and it was permanently terminated by September 30, 1997.[196]

The first satellite-based navigation system was Transit a naval navigation satellite system, deployed by the US military in the 1960s and was operational till December 31, 1996. The Transit’s operation was based on the Doppler effect in which the satellites passed through well-known paths and broadcast their signals on a well – known frequency. The frequency shifted between the received frequency and the broadcast frequency because of the movement of the satellite with respect to the receiver. By monitoring this frequency shift over a period of time, it was possible to identify the location. A minimum of four operational satellites were required for this job. The constellation consisted of six satellites in a polar orbit.[197] The first satellite – based radio navigation system developed by the erstwhile USSR was the Tsiklon.[198] Thirty-one satellites were launched for this purpose during 1967 to 1978. Its basic aim was to provide positioning facilities to the ballistic missile submarines.

The Tsiklon series was followed by the fully operational ‘Tsyklon-B’ or ‘Parus’ system. This system was formally inducted into service in 1976, but the full 22 satellite constellation did not become operational until 1980. Parus satellites

continue to be launched till April 2010, and it is believed that it is now exclusively used for military communications. The Parus was followed by the Tsikada—a simplified system for civilian use. In fact, the Parus is sometimes referred to as the ‘Tsikada Military’ or ‘Tsikada-M’. The Tsikada system was put into service in 1979 and acquired its full complement of satellites in 1986. The Tsikada was largely used by the Soviet merchant marine.[199]