| GPS - Global Positioning System is a satellite | | | | impaired people use this GPS equipment to guide |
| navigation system. First conceived as navigation | | | | their way. |
| aid by the military now number of GPS satellites | | | | Surveying |
| broadcasts accurate timing signals by radio to | | | | Construction workers also use GPS receivers for |
| GPS receivers.GPS provides a set of coordinates | | | | surveying the land to locate boundaries, |
| which represent the location of the GPS unit with | | | | structures, and survey markers, and for |
| respect to its latitude, longitude and elevation on | | | | construction of roads. |
| planet Earth thus allowing them to accurately | | | | Geocaching |
| determine their location anywhere on the earth at | | | | GPS receivers are also used in recreational |
| anytime. It has become an important tool for | | | | activities like geocaching where a hand held GPS |
| map making and land surveying and is also used | | | | receiver is used. Geocachers use this to travel to |
| for very precise time reference needed for | | | | specific longitude and latitude walking or hiking to |
| scientific research like the study of earthquakes. | | | | natural locations, searching for particular objects |
| GPS receivers come in various formats, from | | | | hidden by the other geocachers. |
| devices integrated into cars, to phones to | | | | Aircraft passengers |
| watches. | | | | Airline passengers can use GPS units in some |
| The GPS satellites broadcast accurate clock | | | | airlines inside the aircraft except while landing and |
| information in two forms: | | | | taking off as they have very little risk of |
| Coarse Acquisition code/C/A-This is used mainly | | | | interference. These airlines integrate aircraft |
| for civilian navigation which broadcast at 1,023 | | | | tracking into the seat-back television |
| MHz repeating every millisecond. Each satellite | | | | entertainment system, available to all passengers |
| sends a distinct C/A code, which allows them to | | | | even during takeoff and landing. |
| be identified. | | | | Precise time reference |
| Precise code/ P-code- The P-code broadcast at | | | | For accurate time GPS is used. In time code |
| 10.23 MHz, but it repeats only once per week. | | | | generators GPS is used as a reference clock and |
| The P code is first encrypted into the Y-code, or | | | | also when sensors are deployed they are used to |
| P(Y), which can only be decrypted by units with a | | | | provide accurate time for each recording |
| valid decryption key. | | | | apparatus. Even atomic clocks are set to GPS |
| Applications of GPS: | | | | time.GPS time is counted in days, hours, minutes, |
| There are number of fields where GPS has been | | | | and seconds, in the manner that is conventional |
| used such as: | | | | for most time standards. |
| Military | | | | Location-based services |
| It plays an important role in the military by helping | | | | Location based services also use GPS to locate all |
| to find precise targeting of military weapons such | | | | mobile phones. It provides a location solution is |
| as missiles and precision guided munitions. It also | | | | dependent more on mobile phones and less on |
| provides good location awareness thus helping in | | | | telecommunications network topology. This also |
| controlling of forces and command.GPS satellites | | | | helps to provide specific location information to |
| also carry nuclear detonation detectors. | | | | the mobile phone. |
| Navigation | | | | The biggest problem faced in GPS is that the |
| If you are someone who are likely to always get | | | | atmospheric conditions can change the speed of |
| lost while driving then GPS is what you need in | | | | the GPS signals while passing through the |
| your car. It is used as navigation aid in cars, ships | | | | ionosphere. This effect gets minimized when the |
| and planes. Hikers and trekkers use hand held | | | | satellite is directly overhead and becomes greater |
| GPS receivers to find their way. Even visually | | | | toward the horizon. |