Almost all modern smartphones have built in GPSes, making it one of the must-have features today. With this GPS used together with a mapping service, the smartphone is able to determine real-time position tracking, enabling useful features such as turn-by-turn navigation, as well as receiving or sharing location based information. These location-based services are used by iPhone users on a daily basis, becoming an almost integral part of our lives. How does the iPhone GPS work anyway? The App Quests team is investigates into this mysteriously great and useful technology.
How does the iPhone GSP Work?
Global Positioning System, or GSP for short, uses a network of two dozen satellites owned by the US, initially intended for military usages. The satellite-based navigation system was approved for civillian use in the 1980’s.
These GSP satellites are in orbit and travel around the earth twice daily, and receives and transmits very accurate information from/to Earth. They broadcast very precise time signals together with their current location every 30 seconds. GPSes receives these signals and subsequently interprets the relavant information, to determine the user’s distance relative to the different satellites and its corresponding location n the map. This is usually accurate within 10 meters in latitude, longitude and elevation.
How does the iPhone GSP Work Without Any Signal/Reception
If you are caught in a jam in a rural area, you may have noticed that your iPhone’s Maps app is still able to determine your location, though much slower. You might be wondering, how does the iPhone GSP work if if relies on satellites?
The Apple iPhone has something called the Assisted GPS or APGS. Rather than depending on downloading positioning data from the satellites, the Apple iPhone uses cell towers owned by mobile carriers to determine its location. This can be done through calculations via multilateral of signals between several radio towers of the mobile carrier and the device.
Mobile carriers have very accurate GPS measurements of the locations of their towers. With the information of several towers, the distance can be measured based on the signal strength of all cell towers within range, through the method of trilaterationm or using overlapping areas of signals to locate an intersecting spot, and futher using the measurement of angles to determine the center point. However, using cell towers to determine location would not work in less populated areas where cell towers could be far away beyond reach.
How does the iPhone GSP Work Without a SIM card?
Without a SIM card, an iPhone would not be able to detect or connect to any cell towers nor satellites. However, ,apping services such as Apple Maps and Google Maps also make use of WiFi positioning to make GPS services available, without the use of satellites or to help GPS services become more accurate. How does the iPhone GPS work with WiFi? Basically, the iPhone would detect and connect to all WiFi spots surrounding it, and use the WiFi Hotspot’s location information to detect the iPhone’s location. For this to work, the WiFi setting on the iPhone must be turned to ON.