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In fifteenth Century, due to the backward shipbuilding technology, lack of geographical knowledge, weak sense of rulers, and many other factors can not achieve good navigation. The year fifteenth Century was a period of great development of eastern and Western navigation. In 1405 Chinese navigator -1433, "Zheng He" in the Chinese homemade Sinan navigation rate of the fleet seven voyages through more than and 30 countries and regions, far eastern Africa to Somalia and Kenya area, become China in the world ancient navigation initiative. In sixteenth Century 1569 the rapid development of projection technology of navigation geographer Mukato in twentieth Century became the foundation of modern navigation technology into modern charting has made great achievements in 60s appeared in Omega Navigation System, followed by a more precise satellite navigation system, homemade plotting radar etc..
Loran long range navigation (Loran) is a kind of navigation system developed by the United States for long distance navigation of military carrier. At present, it is widely used in civil aircraft, ship and vehicle navigation. Loran-C is a common version. In Russia there is a similar navigation system, called Chayaka. Loran system is generally a station (Master, M) combined with 2 ~ 5 from the station (secondary station, W, X, Y, Z, etc.) to provide a wide range of navigation services. Time synchronization of each platform by cesium atomic clock. In addition to providing navigation services, Loran also provides clock calibration services. The effective range of Loran in the sea is 2000 ~ 3000 km.
The earliest navigation is navigation (celestial), that is, the use of day, month, stars to observe the positioning of the ancient navigation technology, but is still in use today. Such as the use of the Beidou star to determine the orientation, direction. China's satellite navigation system, borrowing the name of the beidou.Omega Navigation (Omega) navigation service can provide global, all-weather, all the time. Omega system a total of 8 stations, distributed around the world. These stations are synchronized by cesium atomic clocks. Omega uses the 10KHz~14KHz extremely low frequency continuous carrier, transmits the signal. Because the signal wavelength is similar to the ionospheric height, the frequency electromagnetic wave is like a waveguide between the surface and the ionosphere. Can reach a considerable distance. Omega provided by the accuracy of 2 ~ 4 nautical miles (3.7 ~ 7.4 km). With the full liberalization of GPS, Omega lost its unique coverage of the global nature of the September 30, 1997 stop using.
