Global Positioning System

Global Positioning System
From Wikipedia, the free encyclopedia

The Global Positioning System (GPS) is a Global Navigation Satellite System (GNSS) developed by the United States Department of Defense. It is the only fully functional GNSS in the world. It uses a constellation of between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave signals, that enable GPS receivers to determine their current location, the time, and their velocity (including direction). Its official name is NAVSTAR-GPS. Although NAVSTAR-GPS is not an acronym,[1] a few backronyms have been created for it.[2] The GPS satellite constellation is managed by the United States Air Force 50th Space Wing. GPS is often used by civilians as a navigation system.

Similar satellite navigation systems include the Russian GLONASS (incomplete as of 2008), the upcoming European Galileo positioning system, the proposed COMPASS navigation system of China, IRNSS of India, and DORIS of France.

After Korean Air Lines Flight 007 was shot down in 1983 after straying into the USSR's prohibited airspace,[3] President Ronald Reagan issued a directive making GPS freely available for civilian use as a common good.[4] Since then, GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, scientific uses, and hobbies such as geocaching. Also, the precise time reference is used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.

The first satellite navigation system, Transit, used by the United States Navy, was first successfully tested in 1960. Using a constellation of five satellites, it could provide a navigational fix approximately once per hour. In 1967, the U.S. Navy developed the Timation satellite which proved the ability to place accurate clocks in space, a technology the GPS relies upon. In the 1970s, the ground-based Omega Navigation System, based on signal phase comparison, became the first worldwide radio navigation system. The design of GPS is based partly on similar ground-based radio navigation systems, such as LORAN and the Decca Navigator developed in the early 1940s, and used during World War II. Additional inspiration for the GPS came when the Soviet Union launched the first Sputnik in 1957. A team of U.S. scientists led by Dr. Richard B. Kershner were monitoring Sputnik's radio transmissions. They discovered that, because of the Doppler effect, the frequency of the signal being transmitted by Sputnik was higher as the satellite approached, and lower as it continued away from them. They realized that since they knew their exact location on the globe, they could pinpoint where the satellite was along its orbit by measuring the Doppler distortion.

GPS Cell Phone

GPS Cell Phone
by: Roberto Sedycias



The Global Positioning System (GPS) was funded, developed and controlled by the US Department of Defense. Since the late seventies, GPS has become an important aid to navigation around the world. Initially designed for the US military, GPS became publicly available years later and it is now considered an important feature in lots of consumer products.

How does GPS work? Well, basically there are three elements that make everything work: satellites, earth monitoring stations and receivers (ex: cell phone, telefone celular). GPS provides specially coded satellite signals that can be processed in a GPS receiver, enabling the receiver to compute position, velocity and time.

Today, most cell phones (telefone celular) are not limited to carry on just a conversation. Features like mp3 player, digital camera and video camera have all become standards in the latest cell phone models. It is expected that the GPS feature will soon be added to this list, and it will offer the capability of tracking any cell phone user.

The capability of tracking a cell phone user becomes important in emergency situations, like a car accident, thru the use of 911 emergency phone call, where every minute may be a matter of life or death. In situation like this, the GPS system may pinpoint the exact location of the road accident, enabling emergency services to be quickly dispatched.

It is important to mention that so far most GPS system in cell phone (telefone celular) is restricted to tracking information only. However, one can have navigational capability thru the use of full screen cell phone/PDA combos with map displays and other cellular phone accessories, and third party paid services. If one does not want to sign up for a monthly paid subscription service, he can make use of one-time-paid-only software programs that will enable some of the navigational capabilities.

Although there are many benefits in using GPS cell phones (telefone celular), there are some people who are concerned about the violation of personal privacy. Since the US Congress has not authorized location tracking without actual evidence of wrongdoing, there have been court hearings which have not approved the requests of government agencies in obtaining the cell phone GPS tracking information for suspects or ordinary citizens.

This privacy matter has made some progress towards the cell phone user`s rights, since there are some laws that have been passed which guarantees that GPS cell phone users will have some protection from the release of the tracking information, with the exception of 911 emergency cell phone calls (telefone celular). It is expected that these laws will guarantee that the benefits of GPS in cell phones will be enjoyed by everyone without infringing anybody`s privacy.

Sometimes when there is a technological innovation, there are also some concerns about privacy or some rights infringements. But no matter how much of a concern this is, it seems that a compromise will always have to be reached, so that new technologies will take their places in everyone`s lives. After all, we all live in a globalized consumer world. By the way, have you already got your GPS cell phone?

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Buying The Right GPS For Everyday Use

People who are on the road often need something better to guide them along the way. Instead of looking at a map, the best thing to have is a GPS satellite receiver. There are many brands to choose from when selecting this unit from the store. Some of the popular brands are Garmin, Magellan, Holux and Luxor.

Here are some things to keep in mind when buying;

You should ask about the product features of the receiver. Aside from giving road directions, does it also show the terrain of the area? How big is it and how much does it weigh? Does it operate using rechargeable batteries or should they be replaced by new ones?

Another thing to think about is the size of the screen. Of course, how big the unit is will affect that but it won't be a problem if you can zoom in or out. Drivers should keep their eyes on the road and just take a short glance but given this is also unsafe, the ideal device should have a voice warning system. This will inform you where to make a turn and how many miles left to the desired destination.

All GPS manufacturers will claim that it has all the necessary information stored in its computer memory. This may true but can the unit be updated? The more popular brands can do this because it can be hooked up to the Internet.

The most important factor in choosing a GPS unit is if the device is user friendly. Looking at what is available and asking the clerk some questions isn't the answer. You should pick it up and scroll down the menu to see if this can work. This is like putting on an new pair of shoes or putting on a shirt since it is such a hassle to return it later on.

The price of the GPS device varies on the market. You can get one of the low end models or choose the unit that has color and other features. This decision really depends on the budget but those who are able to do some research and compare it with those that are available will surely make a wise decision and use it whenever it is needed. Those who need it should go to the nearest store and get one now.

GPS Buyers Guide, 6 things you must know!

by: Jason Wolf



Yes there are six things you need to know before you buy a GPS for your car or truck. What do most people use a car GPS for? The most popular use is to get turn-by-turn directions while driving from point A to point B. Some popular car navigational units are the Magellan Roadmates, the Tomtom, the Garmin Nuvi units, and the new Navigon gps units.

1 - Screen Size and sound are important. Especially while driving. The screen should be readable and bright, Also Make sure the buttons are big enough for your fingers, so that you aren't pressing multiple buttons at the same time. Vehicles are noisier than you may think. Driving noise can make it difficult to hear weak audio. Be sure to check out the sound quality to make sure you can understand what is being said. It should be clear and loud so that you can hear it in your vehicle.

2 - Downloadable Maps and memory. Most gps units come with maps built in. A lot of them can download maps as well. It is a good idea to puchase one that has the ability to download maps, so that you map doesn't get outdated.

Memory - the more memory the gps unit has, the more locations, waypoints, landmarks, and maps you can save.

3 - The time it takes a GPS to find and display information. This depends on the number of channels a GPS has. The more channels the unit has the better the reception. Take this into consideration. You don't want to have to pull over and wait for it to get map data if you make a wrong turn.

4 - Does the unit speak street names? This is very helpful. If it does not say the street names and it tells you to turn right. You may have to glance at the unit to check the street name. This can be dangerous.

5 - What type of batteries are used with the GPS? Are they normal rechargeable AA batteries or are they special manufacturer batteries? Also how long do they last.

6 - Bluetooth is great for those who need to use cell phones while driving, With Bluetooth the driver can make and receive hands-free calls through the unit's speaker and microphone, and view their telephone book and access caller ID on the screen. What an amazing feature. Of course blue-tooth enabled units are little more expensive.

Those are the six things you need to know before you buy a GPS.

Heres a quick note about mapping data:

All Magellan Garmin and NAVIGON GPS units use NAVTEQ mapping data, while TomTom uses Tele Atlas. I've done research online and found that both NAVTEQ and Tele Atlas are both good and I would not base my decision on which mapping data the gps uses.

Where to buy?

A good place to check prices is at: www.gpsreviewvideos.com

This website has video reviews of numerous gps units and links to compare prices. That way you can watch a video of the gps unit, compare prices from multiple sources online and get the best price.


About The Author
Jason Wolf
http://www.gpsreviewvideos.com
GPS Video Review Site
See how gps units work before you buy.