How GPS Navigation and map works

I have shared my experience with smartphones to be precise android phone through few articles. I am sure all smartphone users will agree with me that it will become part of their life – cos they are always connected through mail, social networking etc. Other than this, one of the most useful features is Maps and Navigation.

This article is to find to know how GPS (Global Positioning System) Navigation, Google maps works

How it works
GPS Navigations was widely used in vehicles and portable devices by hunters and hikers. Now it is essential part of a very basic smartphone. How this technology works?

All GPS enabled devices have a small receiver (antenna) and it detects where we are and there need to be a infrastructure to support this. GPS was originally created for military use and 1st satellite was launched in 1978.  
Since then, they've created a constellation of satellites orbiting the earth. There are around 50 satellites and around 30 of them are active. GPS satellites orbit the globe twice a day and sends low-power radio signal; also the orbits are arranged to make at least 4 satellites visible.

GPS receivers can receive the signal from satellite and calculate the location (altitude) based on traveling time of signal. But this is not enough to show the location. There need to be a database to cross reference the location and show actual landmarks and streets. This is done by the third party software. NAVTEQ and Tele Atlas are 2 biggest database providers

Smartphone should be in visible to at least 3 satellites to calculate exact location. This operation is based on a simple mathematical principle called trilateration: - this is a vast topic and outside scope of this blog.

For accurate location, the device should be in open area, clear view of sky and there need be powerful GPS antenna.

Internet connectivity
To use the GPS in there should be an active connection to the network to download the map data (GPS only tells you where on that map you are, it carries no map image data). If the maps cached on phone, when losing data connection navigation still works. However, if there is no connection and the phone is moved to an area  where map data is not downloaded , map will fail. 

More details into GPS receivers
GPS receiver works the same way a cell phone works. A cell phone is basically a sophisticated 2 way radio. Towers and base stations, arranged into a network of cells, send and receive radio signals. Cell phones contain low-power transmitters that let them communicate with the nearest tower.

As we travel, phone moves from one cell to another, and the base stations monitor the strength of phone's signal. As phone move toward the edge of one cell, signal strength diminishes and in the same time, the base station in the cell phone is approaching notices the strength of signal increasing: - the towers transfer phone’s signal from one to another

Like a cell phone, a GPS receiver relies on radio waves. But instead of using towers on the ground, it communicates with satellites that orbit the Earth.

Even without a GPS receiver, cell phone can provide information about location. A computer can determine our location based on measurements of your signal, such as:

1) Its angle of approach to the cell towers
2) How long it takes the signal to travel to multiple towers
3) The strength of your signal when it reaches the towers

Google Maps and Navigation
Being and android and Google fan, I’ve mostly used Google Maps, Navigation and Earth, which are free and yet awesome.
Some details about Google maps: - the data is compiled by its partner Tele Atlas, which is the world leader in navigation and location based services. The maps are highly accurate and have been hailed for recording extremely rural areas and mapping the terrain correctly. Business and premises which are place-marked on maps have been supplied by directory listings.

Google maps latest update allows the user to save the map to make it available offline. Also I have mentioned about previous release in which inside building view for selected airports and shopping malls. Also the 3D map will be released soon. But in country like India, where 3G is a luxury, this does not make any senseJ. Let’s wait till 2020!! 

The End
Hope you guys enjoyed reading and add please send your feedback through the comments section



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