What is GPS?
GPS stands for global positioning system. It is originally a satellite based system that is owned by the Govt of United States. It is operated by the United States Space Force. It is usually used to track the locations. It uses mathematical principle trilateration to know the location, time and speed. It consists of more than 30 satellites around the world in orbits. Every satellite move around the world two times in 24 hours.
History of GPS
In 1973 the project GPS was started in United States to improve previous navigation systems. The Defense Department of United States developed the GPS tracker containing 24 satellites. First it is used by only United States military before 1980s. And in 1980s the civilian was allowed to use GPS for free. The design of GPS is partly based on radio navigation system. Before 2000s the GPS was not much popular and accurate. It had many limits that time by Govt of United States. But After 2000s it became popular and accurate. Now anyone in the world can use it free of cost. The modern GPS is consists of 33 total satellites. And it is very accurate than previous ones.
How GPS works?
Total 33 satellites are rotating around the earth now but only 31 are in working state. Each of these satellites is almost 20000km far from earth. These satellites are arranged in circles so anytime anywhere of the world there will be 4 satellites. A GPS receiver’s job is to locate those satellites and figure out the distance from those satellites and deduces its own location. All of this system is based on mathematics rule called trilateration. Trilateration is technique which is used to measure distance, speed, and location. Trilateration is a version of triangulation. It uses first satellite to locate the object and then with the help of other satellites it provides accurate location and speed.
In simple words, GPS receiver receives signals to satellites and after receiving signals from satellite GPS uses this information and trilateration to measure the location.
How much GPS is accurate?
When first time the GPS was launched it was not very accurate. Because at that time technology was not like this time and that was first time. But with the passage of time, GPS is become highly accurate. Now the GPS is very accurate and it shows us the exact location.
GPS is more accurate in water than a populous or city area. Because big buildings and other most solid things can stop GPS signals and it becomes hard for the GPS receiver to receive signals from the satellite. And GPS provides us the location using signals and frequencies.
There are several GPS alternatives these days.
- GLONASS ( The Russian Global Navigation Satellite System)
- BeiDou(Chines Global Navigation Satellite System)
- Galileo Positioning System( European Union)
- NaVIC (Indian)
- Quasi Zenith (Japanese)
What is GPS signal?
GPS satellites transmit 2 low power radio signals to the GPS receiver. These signals have the speed of light and they can travel in plastic, clouds, but they can’t travel in most solid things like concrete, buildings etc. That’s why the location in big building areas is not very accurate. However modern GPS receivers are very sensitive and they can receive signals in big cities as well. Every signal has three types of information.
- Pseudorandom code
- Ephemeris data
- Almanac data