GPS Systems, Why They Are Handy
Gone are the days where a person had to use a paper travel map in order to find out how to get from one place to another. Now there is new technology called GPS systems, or global positioning systems. These devices, which have been used by the military for many years have recently become popular with the public. These are electronic devices that come in different forms, from handheld models to display models that are mounted or even a permanent fixture of some newer cars. These devices, which are controlled by satellite, work by punching in a starting address and the final destination address. Once that information is put into the GPS, the GPS will guide the person step by step, turn by turn until the person has arrived at his or her destination. Some GPS systems will actually talk to you and tell you exactly where to turn and when, others are simply an interactive map that will show you on a display when and where to turn, but will not give verbal directions. Along with showing or telling the person where to turn, it also says where you are at, at which direction you are currently heading.
These global positioning systems, or GPS, are very handy to drivers since the driver does not need to be hassled with a large map while he or she is trying to keep their hands on the steering wheel and their eyes on the road. This is particularly true for those drivers that are driving without someone else to navigate for them. These GPS systems are also very handy if a person does become lost. Because the system will tell the person where they are at, they could call for help and be able to tell another person their direction and exactly where they are.
Not only are GPS systems useful for drivers, but they are also very useful to anyone that is unfamiliar with any location that they are at. Take for instance hikers. With hand held GPS systems, they can make the most of their hike and again, if they get turned around, they can find out how to get back on track if they know which direction they should go in relation to the direction they are currently headed.
Of course, this new technology is very handy and can save a person a lot of hassle, but it is important to understand how to use the particular system, and to understand that not all GPS systems work exactly the same way. It is also important to know that with any technology, they may not always work and it is still a good idea to have a traditional back up travel map, just in case.
Whether using an electronic device such as a GPS, or using a traditional map, it is a good idea to become familiar with it and familiar with your destination before you actually leave for any trip. Maps, whether traditional or electronic are only as good as the person that knows how to use and read them.
GPS Basic Information
GPS or Global Positioning System is a fully functional Global Navigation Satellite System. This system uses an artificial constellation of 24 medium Earth orbit satellites. These satellites transmit microwave signals, thus enabling a GPS receiver to determine its location, speed, direction and time. This system was developed by United States Department of Defense and was named as NAVSTAR GPS which was given by Mr. John Walsh.
This satellite constellation is managed by United States Air Force 50th Space Wing. The cost is approximately 750 US dollars every year, including the maintenance cost, replacement, research and development. After shoot down of Korean Air Lines Flight 007 in the year 1983, a directive was issued which made the GPS available for civilian use and has been used extensively since then. It has become a very useful tool for making maps, surveying landscapes, commerce and many scientific uses. It also provides time reference which can be used in many applications which include study of earthquake and telecommunication network synchronization.
A GPS receiver simply calculates the distance between itself and three more GPS satellite. Each satellite has an atomic clock in it continually transmits certain data containing its exact time, location of the transmitting satellite and the almanac. The receiver then measures the reception time of the signal. Thus the distance to each satellite is known. Knowing three such distances, a trilateration is formed. By using a fourth satellite, need for a clock at receiver is avoided.
The Global Positioning System is used in a variety of Military and Civilian Applications. It allows soldiers find their objectives in a dark or completely unfamiliar territory and coordinate troop movement and supplies. GPS receivers which military personnel use are called Commanders and Soldier Digital Assistants. A combination of GPS and communication through radio enables real time vehicle tracking.
It is also used in marking targets as hostile and enables the precision guided munitions to allow them engage these targets with high accuracy. Air to Ground roles of military aircrafts use GPS to find targets. GPS also allows targeting for military weapons like ICBMs, Cruise missiles, precision guided missile. Artillery based projectiles are embedded with GPS receivers and can withstand forces up to 12,000G. These are used for 155 mm Howitzers. Any Downed pilot can be easily located if he has GPS receiver. It is widely used by military for reconnaissance and mapping. Some GPS satellites also have nuclear detonation detectors.
GPS helps civilians a lot in surveying and navigation. Its ability to calculate local speed and orientation is extremely useful. Time transfer is possible because of its capability to synchronize clock. A widely used example of use of GPS is CDMA digital cell phone. Each base uses a GPS timing receiver to synchronize the codes with different base stations and thus making it easy inter-cellular hand off and thus support emergency phone calls and other many applications. GPS equipment has also revolutionized tectonics by measuring the fault motion during earthquakes.
The two GPS developers, Ivan Getting and Bradford Parkinson have received national academy of Engineering Charles Stark Draper prize during year 2003. Roger L Easton received National Medal for technology on February 13, 2006. Other similar tracking systems are Beidou, which has been developed by China and is proposed to be expanded into COMPASS; Galilieo, which is been developed by European Union along with many other countries like India and China; GLONASS, which is been developed by Russia is fully available in partnership with India; IRNSS is India`s proposed regional system and QZSS which has been proposed by Japan.
How GPS Receivers Work
GPS Units make sure you know where you are going no matter where you are. Gone are the days of getting lost easily. A GPS system can cost under $100 for a less-than-fancy model. However, what your GPS Unit looks like is not as important as what it actually does.
The GPS receiver is a handheld, sometimes portable device that works with the Global Positioning System (GPS) network. The GPS network is comprised of 27 satellites that constantly orbit the earth. As the earth rotates, so do the satellites. Of these 27, 24 of the satellites actually work, while three are used as backups. As you can imagine, running the GPS is quite costly.
The GPS network was originally developed by the United States military. The military used it to increase navigational accuracy. However, it was not long before the GPS network was open for use by anyone.
How it works is simple. First, the satellites have multiple orbit routes around the earth. At any one moment in the day, at least four of the satellites are able to transmit information from the satellites to GPS receivers. Of course, it is imperative that the view between the satellite and the GPS unit is unobstructed. That is why GPS receivers sometimes do not work right in areas with high mountains, a lot of trees, or skyscrapers in the way.
GPS receivers work with the satellites. First, the GPS hunts down four of the satellites that can connect with and transmit information to the GPS unit. Once four satellites have been found, the distance to each of the satellites is recorded, and the GPS can pinpoint its location, by the distance it is from each satellite.
This mapping and estimating is based on a principle in mathematics, which is known as trilateration. How it works is by traveling through three-dimensional space. This is complex to understand, but the result is amazing, and it should be what you look for when purchasing a GPS unit of your own.
Trilaterion that works in 3-D is what is used to map your location. A series of spheres line the distance from one place to the next, based on the location of the satellites at the time of the transmission to the GPS receiver. The spheres intersect and meet and as the distances from different locations on different spheres are measured, your exact location is pinpointed. All of the four satellites’ plots work together, to intersect in one place through the spheres.
GPS receivers generally try to use more than four satellites at one time. This provides a more accurate location and less room for error. The Earth is also used as a marker, which works with the GPS network to help pinpoint locations on the surface of the planet.
GPS receivers have to know how far a distance it is from the satellite to the unit. To do this, radio signals sent from the GPS satellites are analyzed. These signals are high in frequency though they are relatively low in power. The better your GPS unit is the better chance you have of using multiple satellites in order to pinpoint your exact location.
Since radio signals travel at the same speed light does, GPS receivers are able to determine how fast the waves travel and how far they have traveled. At random times, the satellites transmit pseudo-random code, which are digital patterns, to the GPS receivers. The GPS unit will then play the digital pattern, though there will be a lag. This lag is based on how fast the signal traveled, and is a major part of the GPS plotting process.
In order to track the signal’s pattern, the satellite and the GPS receiver use clocks, which synchronize together. The Satellite uses an atomic clock, while the GPS receiver uses a regular clock. However, to accommodate synchronization, the clock in the GPS unit is able to constantly reset. This prevents any type of clock problems from occurring.
There are various types of GPS systems. These systems work to fix any inaccuracies and errors in the GPS receiver’s location tracker. These systems include WAAS and DGPS.
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