1. Location Awareness Flashcards
Name 3 methods of outdoor locational awareness techniques?
GPS
IP address
Network triangulation
Describe GPS
Developed by US military in 1970’s. Uses 4 satellites which use 3d spheres to locate a person.
Sun and moon have weak gravitational pull. The error rate is up to 2 meters.
Does not work in doors and can be problems with large buildings.
Describe IP Address location
IP address locations are issued by your ISP. Not entirely accurate, ie mine is Widnes. Can also be reallocated to people all over the but location remains.
Not accurate but used by iPlayer to determine if your in the country, so very general. Can get around with proxy servers and VPN’s
Describe Network Triangulation
Network triangulation takes the signal strength from three cell towers to determine your location.
Not as accurate as GPS, especially in rural areas where there are less towers.
Name Indoor Location techniques
WiFi Positioning System
Bluetooth Beacons
Describe WiFi Positioning System (indoor locational awareness)
Positions via WiFi access points (routers) based on signal strength and fingerprinting. Detection is via the SSID and MAC address.
Gets a RSSI (Received signal strength indication) value between router and client). App can be programmed wth getRssi() to determine signal stength.
Can getSSID or MAC to determine router and then measure signal strength.
Pros:
Tech already widely used
Big range: 150m
Detects floor level
Cons
Relatively inaccurate (5-15m) compared to BLE/RFID
WiFi client based positional not possible w/ iOS, but BLE can be used as an altrnative.
Signal fluctuations can cause erros
Describe BlueTooth Beacons (indoor positioning)
Bluetooth Beacons send signals (cant receive). Cheap, 2 year battery, Determines location via fingerprinting. Can trigger action based on beacon ie local coupon on phone
Pros: Cheap Low energy Flexible Works where other techs dont have signal iOS AND Android High accuracy (
