d> GPS

Introduction to GPS

How does it work?

GPS also known as Global Positioning System is a satellite based navigation system. All GPS’s use a network of 24 satellites placed into orbit by the U.S Department of Defense. This satellites circle the earth twice a day, 2 times every 24 hours. The satellites orbit earth very precisely and transmit signal information to earth. This information is the satellite’s number, its position in space, and the time the information is sent. GPS receivers pick up this information and use it to calculate the user’s exact location and the distance between it and the GPS satellites. More over GPS receiver compares the time a signal was transmitted by a satellite with the time it was received, and the time difference tells the GPS receiver how far away the satellite is. Then with distance measurements from a few more satellites, the receiver can determine the user’s position and display it on the unit’s electronic map. A GPS receiver also uses’ 3 satellites to calculate a 2-D position on the ground (latitude and longitude) and track movement’s. With 4 or more satellites, a GPS receiver can determine a 3-D position (latitude, longitude and altitude). Not only that, a GPS receiver can provide data on direction of travel, speed, distance to destination.


The Global Positioning System was originally developed by the united states department of defense. The main purpose of the GPS was to use it for military purposes. It was used for precision weapon delivery and to provide precise locations of military weaponry. The GPS was first launched in 1978 and became fully operational in 1995. By 1978 the first GPS satellite was launched by the department of defense. In the midst of 1980 more satellites were launched to improve the GPS signals for military and nonmilitary user’s.

How accurate is the GPS

One thing most people ask about GPS is how accurate is our GPS. And this question leads us to another question, which is who is in charge of the GPS and its performance? GPS are owned by the united states government. The U.S Department of Defense (DOD) is responsible for GPS operations and management. The U.S. Coast Guard serves as the civilian interface to the DOD, communicating GPS status information to the public and accepting reports from the public regarding GPS problems or anomalies. In this time and age GPS is very accurate. But there are certain things that can affect the accuracy and speed of a GPS, for example atmospheric effects, sky blockage, receiver quality, and other sources of error. These things might affect the speed and accuracy but still most GPS are still reliable even in a dense foliage or urban settings with tall buildings. Today’s GPS receivers are extremely accurate than they use to be, thanks to their parallel multi-channel design. There are 12 parallel channel receivers and they are very quick to lock onto satellites when they are first turned on, and they maintain strong locks through out there use. GPS are free of cost and can be used everywhere except places where there is no signal. GPS can be used on land, at sea and in the air. The most common airborne applications are for navigation by general aviation and commercial aircraft. At sea, GPS is also typically used for navigation by recreational boaters, commercial fishermen, and professional mariners. Land-based applications are more for drivers and for people walking or biking.

Market Share

There are a few companies that operate by selling GPS devices. TomTom and Garmin are the top sellers of GPS. Garmin have been the lead seller of GPS in recent years. This two companies have some similar features in their products. Both have text to speech conversations with GPS high resolution displays for easy viewing routes Bluetooth 3D map views Points of interest (POI) database and automatic re-routing.

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Apple GPS

The iPhone 3G and all subsequently released iPhone models use A-GPS also called Assisted GPS. Assisted GPS is a system that often significantly improves startup performance (TTFF) time-to-first-fix, of a GPS satellite based positioning system. A-GPS is extensively used with GPS capable cellular phones, as its development was accelerated by the U.S FCC’s 911 requirement to make cell phone location data available to emergency call dispatchers. A-GPS use’s cell tower data to increase quality and precision when it is in poor satellite signal conditions. To be more precise A-GPS uses internet network or connection to an ISP. All iPhone GPS use accesses that are intermediary server when it is not possible to connect directly to the satellite. When a user goes from outdoors to indoors, and a problem occurs with the satellite it was connected too, the iPhone server automatically provides the nearest satellite with additional information to make it possible to more accurately determine users position. The latest Apple versions use wi-fi hotspots and cellular towers to get the nearest and most accurate location fast, when GPS is not the most convenient method of location detection. The iPhone 3GS and latest iPhone models additionally have an integrated digital compass to also provide the direction a user is facing, which is very useful when combined with mapping software. Apple users can use Maps to get directions with real-time traffic information, explore and find new places, and more. And With iOS 10, Maps makes things even easier to find by giving you detailed information and suggestions based on your habits and calendar events. And most Apple GPS are user friendly and very easy to use. When you tap the Search bar, Maps shows you categories for nearby locations, like Gas stations, restaurants, fast food places, and coffee shops. When you tap a category, Maps provides nearby suggestions. To browse the suggestions, swipe up on the menu bar. You can also use the markers to mark your current location. And you can drop a marker to show the distance from one location to another. To avoid tolls and highways, you can go to Settings then Maps then Driving & Navigation. Then tap the sliders for Tolls or Highways. And this also shows you how the traffic is in that area. With everything above being good things about Apple GPS, there are some things that some users believe are bad about Apple GPS. One bad thing about Apple GPS is that there is a hidden application in Apple phones which logs every journey you take without the user’s permission. This frequent Locations feature was quietly introduced to iPhones a few years ago, and almost all iPhones are able to analyze the data and work out where you live, which is very terrifying. But Apple claims the data never leaves your phone without your permission.

Market Share

Some analysts believe that as stand-alone versions are overtaken by cellphones and other devices with navigation technology built in, GPS devices will become low-margin commodity products, like pocket calculators. But others think a smart company could turn GPS devices into premium products the way Apple made its iPod music player stand out from a host of cheaper devices. Owner of the Navman and Mio brands — the top three GPS makers hold around an 80% market share, giving them scale advantages over smaller players. But competition is coming from many directions, including big names like Nokia Corp., Sony Inc., Google Inc. and probably Apple.

Waze GPS

Waze is the world's largest community-based traffic and navigation app. Waze use’s users shared real-time traffic & road info to save time, gas money, and improve daily commuting for all. When someone drives while Waze is open, they contribute tons of real time traffic information to other users. Users can also report police traps, accidents, and other hazards they see on the road. This information help other user’s get road alerts along there route and help them find cheapest gas prices around the shared community. Waze is all about contributing to and benefiting from the common good. Some things that make Waze different from other GPS application are, Community reported alerts including accidents, hazards, police traps, road closures. Waze also have an automatic rerouting as conditions change on the road which is very help full while driving. They also have Live maps, consistently edited and updated by Waze community map editors.

Market share

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Google Maps GPS

Google Maps is a desktop web mapping service developed by Google. Google Maps offers users satellite images, street maps, 360° panoramic views of streets, Street View, real-time traffic conditions, Google Traffic, and route planning for traveling by foot, car, bicycle (in beta), or public transportation. Google Maps' satellite view is a "top-down" or "birds eye" view; most of the high-resolution imagery of cities is aerial photography taken from aircraft flying at 800 to 1,500 feet (240 to 460 m), while most other imagery is from satellites. Much of the available satellite imagery is no more than three years old and is updated on a regular basis. Google Maps uses a close variant of the Mercator projection, and therefore cannot accurately show areas around the poles.


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