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Global Positioning System

The Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). Utilizing a constellation of at least 24 medium Earth orbit satellites that transmit precise microwave signals, the system enables a GPS receiver to determine its location, speed/direction, and time.

Developed by the United States Department of Defense, it is officially named NAVSTAR GPS (Contrary to popular belief, NAVSTAR is not an acronym, but simply a name given by Mr. John Walsh, a key decision maker when it came to the budget for the GPS program[1]). The satellite constellation is managed by the United States Air Force 50th Space Wing. The cost of maintaining the system is approximately US0 million per year,[2] including the replacement of aging satellites, and research and development. Despite these costs, GPS is free for civilian use as a public good.

GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, and scientific uses. GPS also provides a precise time reference used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.

Simplified method of operation

Brawn Grand Prix is a Formula One team based in Brackley in south Northamptonshire, England which was formed out of the ashes of the Honda Racing F1 team in 6th March 2009. In December 2008 Honda revealed that they were going to pull the plug on their Formula One team in an attempt to save the Honda company money during the worsening global financial downturn.

This left one of the best funded and best equipped Formula One teams in the field in limbo while the management team attempted to find a buyer for the team and save 700 plus worker’s jobs at the teams Brackley HQ. Between December 2008 and February 2009 a number of possible buyers’ names were being thrown about by the media and team boss Nick Fry claimed the management was negotiating with a dozen possible buyers. The media reported that the team was close to being saved a number of times by parties including Prodrive, Mexican billionaire Carlos Slim and a ‘consortium of Brazilian investors’ however none of these came to fruition and it was soon looking likely that the only realistic option was a management buyout.

The crying needs for successful and enjoyable holiday travel – getting to the destination, and providing some entertaining distraction along the way – are now answered with the help of heaven-sent, handy GPS-based navigation systems. Whether you are traveling cross-country or taking a quick weekend trip, having a GPS device will make your journey easier, faster and much more fun.

In recent years, GPS devices have begun to mature from barebones units to more feature-packed devices that also let you play music and even make calls from your car. Both GPS- systems and satellite radios are becoming hot add-ons for new cars and rentals, and there are a variety of interesting and ever more affordable options to upgrade your existing vehicle. Today’s systems work well with small and built-in GPS antennas providing visual and voice prompts for upcoming turns, and dynamically adjusting when you take a detour. These systems can normally store at least major highway maps for the entire regions plus detailed maps for a specific region, as well as associated points of interest, addresses and even phone numbers for businesses, gas stations, ATMs, hotels, restaurants, and attractions.

The technology of today has given us an ingenious device with which we can find our way through unfamiliar places. This device is simply called a gps system or to be more exact global positioning satellite. This interesting device was originally devised by the military to navigate their aircraft and other systems with the aid of tracking satellites.

The original global positioning satellite system was designed sometime during the late 1960s. This device was called Transit and it utilized seven satellites and radio signals to receive and send coordinate information. The next improvement to the global positioning satellite system was developed during that same time period. Unlike its predecessor this new gps system worked using an atomic clock.

Even though these were all improvements on the navigational process there were still issues of inefficiency and inaccuracy to be dealt with. To combat this problem the Navy and the Air Force joined forces and created a new gps device. This device was called Navigation System and Ranging or the shorted form was called NAVSTAR. The launch of this device came about during the early 1970s.

With all the technology available to us, there’s no excuse for getting the family lost in an unfamiliar place or stuck in hours of traffic on holidays. GPS is a great devise for in-car use and it’s just as useful when on foot plus it’s a great way to get around a foreign city too. With GPS Rental services this device became even more available and useful. Drivers can find their way through city streets; long reserve trekkers and hikers use the technology to navigate unfamiliar terrain. GPS devices are even more helpful for planning a trip, whether it’s a cross-country trek or a hopscotch tour of your routine stops.

But GPS not only gets you from point A to point B with minimum hassle, it also makes your holiday come alive; with ways to plan your itinerary, track down the best restaurants, and make your holiday more enjoyable.

Here’s a few handy GPS travel tips to help you get the most out of the holiday and avoid the travel woes.

GPS TIPS

The basic principle of GPS navigation system to measure the known location of the satellite to the user the distance between the receiver and then integrated multi-satellite data can know the exact location of the receiver. To achieve this purpose, the satellite’s position can be based on-board clock time recorded in the satellite ephemeris identified. The user to the satellite’s distance from the satellite signal transmitted through the records to the user the experience of time, and then multiplied by the speed of light received (due to the interference of the atmosphere ionosphere, this distance is not the user and the real distance between the satellites, but pseudorange (PR): When the GPS satellites to work, it will continue to use 1 and 0 binary symbol composed of pseudo-random number (PN for short) launched navigation message. GPS pseudo-code system uses a total of two, namely civilian C / A code and the military of the P (Y) code. C / A code frequency 1.023MHz, repeat cycle of a millisecond, the code distance one microsecond, equivalent to 300m; P code frequency of 10.23MHz, repeat the cycle of 266.4 days, Code spacing of 0.1 microseconds, equivalent to 30m. The P code Y code is formed on the basis of confidentiality better performance. navigation message includes satellite ephemeris, work status, clock corrections, ionospheric delay correction, atmospheric refraction correction and other information. It is in the solution from the satellite signal modulation up to 50b / s modulation in the carrier frequency on the launch. navigation data included in each of the main frame 5 sub-frames per frame size 6s. the first three frames of all 10 code; repeat every 30 seconds, updated hourly. After the two were 15000b. navigation message in the contents of the main remote codes, code conversion, the first data blocks 1,2,3, including the most important was ephemeris data. When the user receives the navigation data, the extraction of the satellite time and do it with their own clock compared satellite and the user will be aware of the distance, and then use the navigation data in the satellite ephemeris data, calculate the location of the satellite launch when the message the user in WGS-84 geodetic coordinate system position, velocity and other information can be learned.
GPS satellite navigation system can be seen part of the role is to constantly launch navigation message. However, users accept the machine using the onboard clock with the clock can not always synchronized, so in addition to the user’s three-dimensional coordinates x, y, z, but also introduce a ?t is the time between the satellite and receiver differential as unknown, then four equations out of these four unknown solution. So if you want to know the location of the receiver, at least four satellites can receive the signal.
GPS receiver can receive the exact timing can be used to nanosecond time information; for forecasting the next few months in which broad locations satellite ephemeris; used to calculate the required positioning satellite coordinates of the broadcast ephemeris a precision of several meters to tens of meters (each satellite is different at any time change); and GPS system information, such as satellite status.
GPS receiver of the code can be measured from the satellite to the receiver, as with the receiver clock error of satellite and atmospheric propagation errors, it is called pseudorange. 0A code measured on the pseudo-range as UA code pseudorange, the accuracy is about 20 meters, measured on the P code pseudo-range as P code pseudo-range, precision is about 2 meters.
GPS receiver to receive satellite signals, decode or use other technology, the information on modulation in the carrier removed, you can restore the carrier. Strictly speaking, the carrier phase should be known as the carrier beat phase, which is received by the Doppler frequency shift effects of the satellite signal carrier phase and the receiver local oscillation signal phase difference. Generally determined by the receiver clock time measurement epoch, to keep track of the satellite signal, you can record changes in the value of the phase, but the start time of observation and satellite receiver initial phase of the oscillator is not known, since epoch beginning phase integer not know about that ambiguity, only as a parameter in the Data Processing Solution. Phase observations are accurate to the millimeter, but only solved ambiguity, only the relative positioning, and continuous observation for some time to use the phase observations, and to achieve better than the meter-level positioning accuracy of only phase observations can be used.
By positioning mode, GPS positioning into a single point positioning and relative positioning (differential positioning). Single point positioning is only one receiver according to the observation data to determine the way the receiver position, it can only use pseudorange measurements can be used for rough travel, etc. navigation. Relative positioning (differential position) is based on two or more receivers of observational data to determine the relative position between the observation points the way, both can be used pseudorange phase measurements can be applied, geodetic or engineering survey shall be phase observations using the relative positioning.
In the GPS observables includes satellite and receiver clock error, atmospheric propagation delay, multipath effects, etc. error, even when in the position calculation by the satellite broadcast ephemeris error, and during most of the public when the relative positioning error was offset or reduced, thus positioning accuracy will be greatly enhanced, dual-frequency receiver can view the two frequency ionospheric measurement error of the atmosphere to offset a major part in the high precision, when the distance between the receiver (there is significant difference between the atmosphere ) should be used in dual-frequency receiver.