GPS – A Technology That Facilitates Critical Location Determination

The Global Positioning System (GPS) is a scientific marvel that is made possible with the help of a group of satellites transmitting precise signals, in turn assisting the users to have a display based on precise calculation for exact speed, location as well as time. This near to perfect space based radio positioning system provides such crucial three-dimensional information and further finds its application in varied forms.

The position information provided by GPS is useful to locate lost and misguided boats, troops, hikers, professional boaters, etc. For anyone carrying a GPS receiver, the system provides the accurate location and time. The precision may vary from technology to technology. But some advanced satellite based systems provide accuracy to the nearest centimeter.

How it Works?

GPS uses satellite based transmitters as compared to previous navigation systems that used ground based transmitters. Using the former gives more accurate results on time and location.

GPS consists of three parts:

• The Space Segment: Satellites orbiting the earth technically called The Space Segment
• Receiver: User-owned GPS Receivers to catch the transmissions from the satellite
• Control Segment: This consists of ground stations that need to monitor and control the movement of satellites.

GPS receiver provides information on location in the form of three dimensions – latitude, longitude and altitude along with the time. The GPS is a constellation of twenty seven satellites out of which twenty four are used for processing signals emitted by the GPS receiver. As and when the GPS receiver makes a connection with these satellites, it calculates three nearest points and determines the position of the user.

Once the position is determined, other information like speed, distance to destination, track etc can also be calculated.

Possible Sources of Errors

Though GPS is quite accurate in position determination, the accuracy of its information can be hampered by the following:

• Atmospheric Delays: The delays caused due to the time the satellite signal takes to cross the atmosphere and reach earth.
• Timing Errors: The potential difference in the time indicated by the atomic clock onboard the satellites and the receiver’s clock.
• Multipath Error: When the signal transmitted from the satellite hits a tall building and gets reflected, it increases the travel time before it finally reaches to the receiver.
• Blocked Signal: Caves, tall buildings etc can block the reception of the signal and hence hamper the accuracy.
• Orbital Errors: Inaccuracy in the reported location of the satellite.

From the above, we can understand that with the help of a GPS receiver, a user can utilize it for location application with much precision. However, the calculation and the working is not an easy task. Taking care of the errors and other possibilities, valuable information on position determination can be obtained and shared.

So no matter wherever on earth you are and at whatever time, if you are carrying a GPS receiver, you are close, very close indeed!

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