Location Technologies

Key Resources NASA GPS Latitude and Longitude www.nasa.gov www.gps.gov http://www.realestate3d.com/gps/latlong.htm

Location Applications Search Location Rendez-Vous Navigation Survey Mapping

Location Technologies Triangulation Satellites Global Positioning System (GPS) SatPhones Radar/LIDAR Cellular Telephone RFID/WiFi

Triangulation Given the location of two known points, I can use geometry to calculate the location of a third point by measuring the angles between the known and third points. Can use visual, electromagnetic or other means Speed and direction can be gleaned from multiple observations

Triangulation

Triangulation Example Suppose distress signals are received at Pittsburgh and Beaver Falls. Pittsburgh measures the angle of the signal as 70 degrees off North. Beaver Falls measures the angle of the signal as 30 degrees off North. Where is the distress signal coming from? Location Airport Lat Long Pittsburgh PIT 40.5 -80.22 Beaver Falls BVI 40.75 -80.33

Triangulation Example tan a = (P?Long - P1Long)/(P?Lat - P1Lat) tan b = (P?Long - P2Long)/(P?Lat - P2Lat) a = 70, tan a = 2.7467 b = 30, tan b =.5773 2.7467 (P?Lat - 40.5) = (P?Long + 80.22) .5733 (P?Lat - 40.75) = (P?Long + 80.33) P?Lat = (P?Long + 80.22)/2.7467 + 40.5 P?Lat = .3641 P?Long + 69.706 P?Lat = (P?Long + 80.33)/.5733 + 40.75 P?Lat = 1.732 P?Long + 179.9 1.744 P?Long + 179.9 = .3641 P?Long + 69.706 1.3799 P?Long = -110.194 P?Long = -80.557 P?Lat = 40.375

Antennas Whip Omni-directional Dipole Direction Sensitive

Antennas Parabolic “Dish” Directional Aimed Phased Array Tuned

Satellites Orbital Classifications High Earth Orbit (HEO) ~22,300 miles Orbital period ~ 1 day Medium Earth Orbit (MEO) Low Earth Orbit (LEO) Hundreds of miles Orbital period > 1 hour

Satellites High Earth Orbit (HEO) Communications Geostationary/Geosynchronous/Synchronous Stationary 22,300 miles Altitude Circular Orbit Equatorial Orbit Orbital Period = 1 day

Communications Satellites Voice Data Broadcast

Communication Satellite Technology Ground Station Converters Amplifiers Antenna Dish – Parabola of rotation Aiming - fixed Azimuth – degrees off South Elevation – degrees of horizontal

Telstar Telstar I 07/10/1962 Telstar II 05/07/1963 AT&T - NASA

Tracking and Data Relay Satellite TDRS 7 (G) 07/13/1995 NASA

Dish Antenna Aiming http://www.dishpointer.com/ Earth Location Latitude: 40.0090° Longitude: -83.1230° Satellite Name: 45.8W TDRS 4 Altitude: 38614km Elevation:  30.0° Azimuth (true):  130.1° Azimuth (mag.):  136.9° using Compass

Mobile Satellite Communications

Satellites Medium Earth Orbit (MEO) Space Shuttle Miscellaneous Satellites

Low Earth Orbit Satellites Altitude – hundreds of miles Orbital periods – little more than an hour

Satellites Low Earth Orbit (LEO) GPS Satellites Spy Satellites Survey Satellites SatPhone Satellites

Spy/Survey Satellites Polar orbit

NASA Arctic Ice Survey

XM WX SkyWatch

Spy Satellite Image

Spy Satellite Image

GPS U.S. Department of Defense (DOD) Originally - 24 satellites 1973 Overcame limitations of previous earth based navigation systems

GPS Now 32 satellites – spares Orbits 60 degrees apart 55 degrees inclination Multiple satellites visible at any point on Earth at any time

GPS A GPS receiver calculates its position by precisely timing the signals sent by multiple GPS satellites high above the Earth. Each satellite continually transmits messages containing identification, timing and location information.

Trimble GPS Unit

SatPhones Iridium Globalstar Thuraya 66 satellites Polar orbits 485 miles altitude Globalstar 40 satellites 876 miles altitude Thuraya

Iridium SatPhone

Cellular Telephone Network

Cell Phone GPS HTC EVO

Radar Radio Detection and Ranging Radio signals reflect off density masses (objects, clouds) Sweeping or pulsing Speed and direction are computable from multiple scans

Sweep image Radar Scan

Lidar Light Detection and Ranging Uses Radiation in the light spectrum Can detect finer differences Lidar Image

Local/Indoor Location WiFi Bluetooth RFID