GPS and cellular triangulation

As we know, GPS is a positioning system signals from a satellite network. The GPS receiver calculates the time that the signals from at least three satellites are slow to arrive and from then calculates its position to within a few meters.

This is possible because both the satellites and the receivers have synchronized clocks with an almost absolute precision. Because radio signals travel at the speed of light, any delay would result in errors of several KM. An example of how sitema be precise is that the satellites have to be adjusted in a fraction of a nanosecond periodically to correct minor deviations resulting from the gravitational difference between clocks on Earth and in space (the stronger the gravity, the slower the flow clocks, as predicted by the law of relativity).

The first GPS receivers were much simpler than today. They provided only the latitude and longitude, the rest was on account of the user who needed to calculate the map. :)

The combined current location coordinates with digital maps and software that calculates the position on the map provides directions, traffic information and other services for which you normally pay an annual fee:

We can say that 25% of the cost of a GPS device match the current basic circuits that calculate the coordinates, 50% correspond to the rest of the hardware (processor, memory, screen, etc..) Responsible for other functions and the remaining 25% correspond to software and additional services.

That's where the bluetooth receivers, which, include only the basic circuits, combined with a Bluetooth transmitter, used for communication, they cost much cheaper:

Bluetooth GPS receivers can be combined with a PC or a laptop (just find the appropriate software), but the most common is to combine them with a smartphone, which receives the coordinates and performs other operations, running the software with the maps and providing directions. Everything is processed by the smartphone, from the coordinates calculated by the GPS receiver. In the case of smartphones from Nokia, for example, you would use the Nokia Maps:

Nokia Maps is a free application that comes preinstalled on some phones and the other can be installed through the "Applications> Downloads". However, you must pay a subscription to access the navigation service. Another option is to simply use Google Maps also supports an external GPS receiver and is entirely free.

For those who do not have the GPS receiver, it offers a free phone location through triangulation, which indicates its location to within 1800 meters (in most cities). The cellular triangulation is based on the same principle of GPS, but works based on the signal strength of cell towers:

The idea is simple. As you move away from a tower, the signal is weaker, but in return, the other towers signal gets stronger. If the software knows the location of the towers nearby, you can calculate its position based on intensity and response time of each one. You can also do the opposite, finding the device based on information collected by the towers, a service offered by some operators. Accuracy is not nowhere near as good as a GPS, but the advantage is you do not need any additional hardware.

In the case of Google Maps, the major limitation of triangulation is that it does not track your speed, limited to show their location within a set of preprogrammed points (ie, you start at one point and moves as the point suddenly moves to another location, 800 or 1000 meters away). It only helps you locate the map and from there to reach the place you're looking for.