Although Global Positioning Systems have many benefits in regards to improving some aspects of our lives the equipment is still at its developmental stages and needs to overcome some potential problems in order to for it to be a successful tool to use in the future. Some of these errors are natural such as the frequently moving ions in the atmosphere, whilst others are artificial such as radio frequency interference. These errors will be briefly discussed noting how the interferences come about and how they can be possibly avoided. For a more detailed explanation on these types of errors visit the University of Montana's [GPS] site.
According to Larijani “The Global Positioning System is not terror proof, each of the three segments – space, control and user is vulnerable to particular threats from hostile sources, accidents or human error� (1998, pg 156). Generally, a hand held GPS device can pinpoint a location within 5 to 15 metres (Ackroyd and Lorimer, 1994). For Global Positioning Systems, accuracy is an important component of the equipment and certain errors may cause some serious problems for the user during navigation.
For example intentional interference such as deliberately crowding the airwaves with noise to obstruct others from obtaining a clear signal is known as jamming and can cause an error with the signal. However, equipment is constantly being updated in order to correct the satellites, when jamming is directly aimed at one receiver (Cooksey, [GPS], 2004). In addition to GPS being susceptible to electronic attack, a receiver can be “spoofed� or technologically modified for malicious purposes (Larijani, 1998). This “spoofing� causes the GPS equipment to process fake signals and misrepresenting the results. “Users being spoofed are unaware that the fixes they are obtaining are counterfeit and may wind up far off their intended course.� (Larijani, 1998, pg 56) These are some of the intentional errors that occur that prevent people from using GPS for accuracy. Apart from the technical and deliberate errors with Global Positioning Systems, some environmental causes can interfere with the satellite signal and the device. For example multipath errors occur when a part of the satellite signal bounces off an object such as a building and confuses the receiver causing the signal to split resulting in an incorrect reading (Kennedy, 2002). Other environmental factors such as the ions in the atmosphere can interfere with the signal such as when a GPS signal passes through the ionosphere and troposphere it is refracted, causing the speed of the signal to be different from the speed of a GPS signal in space (Cooksey, [GPS], 2004). In addition to this, water vapour, ice clouds, snowfall and the sun can delay the GPS signal to the satellite (Larijani, 1998) and therefore create problems in relation to obtaining a correct reading. Above all, human error such as lack of training with the equipment can extremely impact on the precision of the signals and the information entered into the device in the beginning. In order to complete a test that can help measure the accuracy of the GPS receiver see the link under Pages of Interest.
Although there may be many problems associated with the accuracy of GPS technology, there are ways of correcting these errors in order to keep the equipment functioning normally. For example it is important to be aware of the errors, avoid situations where the signal might be interfered with and maintain the care of the GPS devices.
Pages of Interest
GPS Errors and Measuring the Receivers Accuracy
See Also
References
EmilyOwen 09:33, 29 Oct 2004 (EST)
