Global-navigation Satellite Systems (GNSS) provide navigational data to airborne transportations and various other applications. Mainly two satellite constellations are in use today for navigational purposes. They are global positioning system (GPS) which is provided by the United States and global navigation satellite systems (GLONASS) which is provided by the Russian federation [1]. GPS and GLONASS satellites fly in medium Earth orbit (MEO) at an altitude of approximately 20,200 km and 19,100 km respectively. These satellites primarily transmit the timing and a data message consisting of its orbital parameters which are received by the GNSS receivers to calculate the range from the satellite which will further provide a relative three dimensional position and time from the satellites. Many other states are coming up with their own regional navigation satellite systems. Europe is coming up with European Geostationary Navigation Overlay Service (EGNOS), Japan is moving forward with Multifunctional Transport Satellite (MTSAT) and India is targeting to have its own regional navigation satellite systems christened as GPS Aided Geo Augmented Navigation (GAGAN) by the end of the year 2014. This will aid in providing more precise and advanced navigation. Thus the global nature of GNSS makes it necessary to have a close coordination between all of the states.
The data from the satellite based navigation systems can also be used for trains, buses and other locomotives. Further the navigation data are also important for military in warfare and in battlefield. Thus the high speed and precise satellite based navigation systems are becoming a necessity of the future. However there are many challenges to overcome to make fast and accur...
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The invention of the GPS started with Dr. Ivan Getting leaving his position at Raytheon Company, and armed with the knowledge of what was at the time the most advanced navigational technology in the world, they began developing the Global Positioning System. He, Roger L. Easton, and Bradford Parkison began in the 60’s with a constellation of 24 satellites (placed in six orbital planes) orbiting the earth at a very high altitude (about
At higher frequencies, the dielectric constants are almost independent of frequency. This is because, at higher frequencies periodic reversal of the field takes place so rapidly that the charge carriers will hardly be able to orient
Reading, Gwem. "Radar Operator in WW2." Letter. 8 Nov. 2003. N.p.: n.p., n.d. N. pag. BBC WW2 People's War. Web. 23 Apr. 2014.
"Radar during World War II." - GHN: IEEE Global History Network. N.p., n.d. Web. 16 Feb. 2014. .
Wire time (or panghantar such as an antenna) conducts alternating current, electromagnetic radiation is propagated at the same frequency as the electric current. Depending on the situation, electromagnetic waves can be waves or like particles. As a wave, characterized by speed (speed of light), wavelength, and frequency. When considered as particles, they are known as photons, and each has an energy associated with the frequency of the waveform shown by the Planck relationship E = Hν, where E is the photon energy, h is the Planck constant - 6.626 × 10 -34 J · s - and ν is the frequency of the
MTC ONLINE, " Reports of Current Experimentation with Microwave and EM Weapons," <http://www.heart7.net/mcf/1.html> (10 August 2003)
NSSS states a few current trends in space as being “congested and contested” (NSSS, 8), which is shaping our space strategic environment as well as fueling debates for space weapons. “Congested” trend refers to the current “60 nations and government consortia that own and operate satellites and the expectation to have 9000 satellite communication transponders in orbit by 2015.
Around 1886, Heinrich Hertz demonstrated experimentally the existence of radio waves. It is said that Hertz only smiled incredulously when anyone predicted that his waves would one day be sent round the earth. Hertz died in 18...
The following is a brief illustration of the principles of GPS. For more information see previous chapter. The Global positioning System (GPS) is a satellite-base navigation system that provides a user with proper equipment access to positioning information. The most commonly used approaches for GPS positioning are the Iterative Least Square (ILS) and the Kalman Filter (EKF) methods. Both of them are based on psuedorange equation:
“One would think that so important a contribution to the world’s technology would be chronicled with great care at every step…This, unfortunately, is not the case, and for reasons quite understandable” (Page 14). Sometimes history can be hard to distinguish from truth and legend, the history of radar is no exception. Many contributions have been made to the development of radar over the years. For many years prior and during the Second World War, radar was considered a top-secret military tool. Once it was made public, people used the existing information about radar to come up with their own variations for different applications. As a result, the true origin of radar has become blurred within conflicting claims.
There was a time a person would use a roadmap to get from one location to another. Some also would stop and ask for directions. Today, you seldom see paper maps and people stopping at a local gas station for directions. Many vehicles come with a navigation system that provides a real-time map of the vehicle’s current location as well as systematic directions to requested destination.
The Global Positioning System consists of three sections, 1.satellites which are orbiting the planet, 2.there are numerous control/monitoring centers here on the ground, and 3. gps receivers which are used by their owners. The satellites send down signals from orbit, which are received by GPS receivers on the ground in the air or on the water, the GPS receiver then converts this information into a location longitude, latitude and altitude along with time.
‘ICAO Performance Based Navigation (PBN) Programme’, 2011, ICAO [Online] Available , Accessed 15 June 2011.
If a radiowave of constant amplitude is incident on the irregularity slab of thickness L (Fig 2.2) where the layer is assumed to be a phase changing screen, the wave changes its phase when propagates through it. The emergent wave is represented as,