Great strides have been made in location-based technology since the days when sailors used a crude compass to navigate their way across uncharted waters. Today, a global positioning system (GPS) is maintained by the United States government, and this navigation tool allows the owner of a receiver to determine his or her location by communicating with four or more GPS satellites. This technology has a number of uses and plays a vital role in operations performed by military, civil, and commercial users. GPS technology even helps pilots navigate the commercial air space.
As additional advancements have been made in the field of GPS technology, some organizations have turned to more sophisticated devices to achieve their tracking needs. For instance, differential GPS devices and non-directional radio beacons are used more frequently by groups requiring a higher level of location accuracy. This article will take a closer look at these two location-based technology alternatives.
These devices are known primarily for their improved accuracy. Professionals who work in search-and-rescue operations need a higher level of accuracy to track down individuals, so they use differential GPS devices. Top-of-the-line units outfitted with this technology boast accuracy to ten cm, whereas traditional GPS devices promise accuracy within fifteen meters. The reason differential GPS products offer such a high level of accuracy is because they communicate with a network of fixed, ground-based systems to measure location. These systems carry a known, fixed position that is compared to the location measured by traditional GPS systems. The ground-based devices then compare the measurement with the known location to produce a digital correction signal. This digital correction signal allows the differential GPS device to provide more accurate measurements when locating people or devices in wooded areas, at sea, or in areas where a cell phone is unable to attain service. A satellite based augmentation system is similar, with the exception being it uses orbiting satellites instead of ground-based systems to transmit corrections.
Non-Directional Radio Beacons
Non-directional radio beaconsare radio transmitters situated at a known location, and are most commonly used for aviation and marine navigation. Unlike some of the GPS resources mentioned above, non-directional radio beacons do not use location information to provide directions. These beacons emit signals from their fixed location, which pilots can use to determine where they are located. Signals also indicate which specific pathway an airplane should follow, which means in-air collisions are prevented by setting aside specific airways for each aircraft.
The signals that non-directional radio beacons emit follow the curvature of the Earth, which makes these signals more beneficial than VHF omnidirectional range signals. In essence, these signals can be received at a lower altitude from a greater distance. However, VHF omnidirectional range signals are actually more common in developed countries, while non-directional radio beacons are more common in undeveloped areas or densely populated regions of developed countries.
Differential GPS devices and non-directional radio beacons are alternatives to traditional GPS systems that allow military, civil, and commercial users to more accurately pinpoint their location.