There is a lot of Confusion between GPS and GPRS both associated with Mobile Phones in the last few years. WhileGPRS has been with mobiles for quite some time GPS made its entry relatively a new.
GPS For Mapping
GPS means Global Positioning System. This is a system comprising 24 satellites positioned up in space around the globe over at about 20, 00 KM . Due to the position of those satellites, it became possible to assign an address to every meter of the surface of the earth, including those over the ocean. The 24 GPS satellites, or Space Vehicles (are rotating in different planes (six) ie orbital planes with four satellites in each. Your Cell phone receives signals from these satellites.
The satellites relative postion ( normally 3-4 satellites are seen by every GPS receiver (ie your Phone) and your location on earth is calculated by the Phone by a process called “triangulation” which is used in two dimensional Geometry in High Schools (3 D version in thiscase).
GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. GPS receivers take this information and use triangulation to calculate the user’s exact location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, 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.
GPRS for data (internet)
GPRS stands for General Packet Radio Services. This is a way of sending data through radio waves that are currently being used to transmit voice. The data in digital form is sent out in packets, or in mini-bursts that are decoded by the handsets that are GPRS-enabled. EDGE is an improvement over GPRS and 3G is a further improvement over the same. While GPRS / EDGE offers speeds of the order of 100-180 kbps, 3G/HSDPA promises speeds of maximum 7 MbpS.
Most of our Operators have a mix of Radios that support EDGE/HSDPA/3G. Depending on the BTS in your location your data speed varies even if You have asked for and has been paying for 3G.
Conclusion
It is easy to see why one alphabet or the lack thereof can make such a world of difference. Now we know that GPS is a positioning system aimed at helping you find your location on the face of the planet, whereas GPRS is a radio service that is used to send data wireless.
Your Cell Phone may have both or most probably only GPRS/EDGE in lower models but not GPS..