In recent years, Global Positioning Systems (GPS) have become one of the most popular automobile accessories. GPS works through a series of transmissions between their two components, satellites and receivers. Originally designed by the government for military use, GPS systems are still managed by the federal government, specifically the Department of Defense. The path to GPS technology required centuries of scientific advancement; even today these systems’ technology is constantly evolving.
Navigation before GPS Devices
The need to determine locations and plan travel required ancient civilization to be creative with their direction systems. Latitude and longitude measurements were developed during Greece’s classical age. While this advancement made identifying a specific location easier, it did not necessarily enhance the basic types of human travel. Therefore, most ancient travelers relied on the location of the stars for guidance. By following the bright North Star or other constellations, sailors were able to travel from one sea destination to another. But, since stars are only visible at nighttime, this method was not foolproof.
Prior to GPS devices, navigation was based primarily on cardinal direction, commonly known as a compass. A compass contains a magnetic needle which always points to the equally-magnetic North Pole. By positioning themselves in relation to the northern and southern hemispheres, an individual could determine which way to travel to their destination. Of course, the East-West setting of the sun provided further guidance. A sextant, a device using mirrors to determine the relationship of a fixed object to stars and the horizon, was developed several centuries later to supplement the compass.
The Development of GPS Devices
The development of GPS devices began in the 1960s when the U.S. government released a satellite into space to assist in locating ballistic ships and submarines. Over the next 23 years the Navy, Air Force and other agencies of the Department of Defense would develop, expand and change the science of this location program for military purposes. The name of the program changed several times over the years, but at the end of its run it was known as “NAVSTAR”.
It was not until 1983 when one of the satellites caused a commercial plane to be shot down that the NAVSTAR system was declassified and made available to the general public. Although in an extremely rudimentary state, this declassified program was the beginning of the current GPS program. From 1989 to 1997, 28 satellites were released to create a complete “GPS constellation”. During the Gulf War, the U.S. military tested and found successful the established GPS system. By using GPS during the War, the military was able to identify and focus their assault on specific targets, resulting in a quick victory.
How GPS Devices Work
The term “GPS” universally refers to the two components of these systems: satellites and receivers. A GPS satellite transmits signals to a receiver on the ground that tells its location and time; the receiver is a passive device that collects the transmitted data and calculates its location and velocity. These calculations are then used to provide the receiver’s operator with the exact coordinates of their location and potentially directions to their intended destination. The satellites are operated by the U.S. Department of Defense, and specifically by the Air Force. There are 24 satellites in operation at all times, each with a twelve hour orbiting pattern. The Air Force relies on ground stations to oversee and manage the 24 satellites.
GPS Uses Today
Despite being originally designed for military use (and still being used by the many branches today), GPS has established its place in civilian life. Today, GPS is used in planes and emergency equipment, such as fire trucks, and is also available in and on numerous devices, for example automobiles, phones and computers. Built-in and portable systems are also offered. GPS is also used to monitor the health of the ozone layer in the atmosphere and by farmers to plot and monitor their fields.