GPS is currently one of the more mature technology. Google maps, satellite navigation, etc., we know the global positioning system (GPS) is the following
When you go out in the open air, what will affect the performance of Gps?
Solar power satellites since the 70 s were planted by the us department of defense has been around the earth. Satellite is at a speed of 7000 miles per hour in an orbit about 12000 miles above the earth's surface.
So the space satellite is how to deal with you in the brewer street or frith street? Each satellite orbit the earth in a very precise path run twice a day, send the microwave signal to a GPS receiver, it receives the data, and USES triangulation to determine your exact location. At any one time, the receiver need to detect at least three latitude and longitude and four satellites to add your height.
Trilateration is what? Basically, a smartphone or a running watch the receiver will spend time to send signals from the satellite and the receiver signal of the time, and use the difference to calculate how far the satellite. It repeats this distance and time lag measurements relative to the receiver (you) more satellites, and then can calculate your exact location, and follow up the mobile.
GPS satellites are not actually there. A system called GLONASS opponent using 24 Russian aerospace defense forces satellites, some smart phones and wearable devices include two receivers, in order to increase your chance of precise location is detected, and accelerate the whole process of sending signals and measure the distance of up to 20%. Michibiki - or Japan's own GPS systems, casio's upcoming Android Wear smart watch will support.