Alternatives to GPS
One alternative to GPS that was developed by the Military in WWII, but was cancelled in 2010, is LORAN-C. Although it was sought to be phased out by GPS, it was kept around as a failsafe for GPS. LORAN stands for LOng RAnge Navigation and was a terrestrial radio system that functioned in the spectrum of 90 to 110 kHz. The way LORAN-C works is with the use of stations being the principal, and master paired up with two other stations being the slave and secondary. A pulse is sent out from the master station, and the pairs of stations calculate a time difference in between the master stations and the slave stations to get an approximate location of the boat, plane, or car. This series of pulses are called LORAN chains. Another alternative to GPS is GLONASS, or The Global Navigation Satellite System. This Russian system has 21 satellites works great for its home country. However, this system is intended to expand around the world competing with the USA’s system. The system is designed to work be continuously transmitting two coded signals in two frequency bands. This way, anyone can find their relative position based on measurements from the satellite. Europe has also has a form of global positioning called Galileo. It functions much like GPS except they only have 18 satellites in orbit but eventually plan to have 24 in orbit in the next few years.In China, the Compass angulation system, which is different from their current system (Beidou-1), is set to have 35 satellites in orbit by 2020. It uses three bands and its range of signals is based off of the CDMA principal. Finally, India plans to implement its own system by 2012-13 which would consist of sending and receiving S-band signals ranging from 2-4 kHz. This project is known as the Indian Regional Navigational Satellite System