Don Mason Associate Director Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Location Tracking Not one, single technology Convergence of several technologies Systems for Tracking inventory, livestock, vehicles, or humans Delivering location-based services to wireless devices Current Technologies Cameras (monitoring, surveillance) Bumper beepers Two-way pagers and cellular telephones Geographic Information Systems (GIS) Global Positioning System (GPS) Vehicle event data recorders (EDR) Radio Frequency Identification (RFID) Wireless Local Area Networks (WLAN) 911 and Enhanced 911 (E-911) Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 1
Our Focus Today Beepers Cell phones Networks and how they work Cell site location information (CSLI) Global Positioning System (GPS) Bumper beepers Beepers For tailing autos without being observed Can be from 1 x2 to 3 x5 Placed inside bumpers or attached to undercarriage Require antennas for maximum range Tracked by radio signals Provide directional info up to five miles Two tracking autos give more precise triangulation Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 2
Cellular and Smart Phones Mobile / Cellular phones Positions of mobile phones can be tracked, even on the move Cell phones register their locations with nearest cellular towers, approx every 7 sec s s Nearby antenna towers / base stations pick up signals, roam phone to adjacent towers as appropriate Active calls not required (most systems) Multilateration based on comparing multiple antenna signal strengths, pattern Cell Phone Technology Has become important public safety tool Helps find people in trouble While GPS helps people find their way out of trouble Can locate lost or missing persons (or their phones) Can locate lost or missing persons (or their phones) Even OnStar uses cellular network to communicate with GPS receiver in car Accuracy dependent on base station density More precise in urban areas with more towers Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 3
Towers tri-directional May be disguised Mobile Telephone Cells Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 4
Sample Tower/Sector Comparing signal strengths Time delays Angles of arrival Three nearest towers Triangulation Triangulation Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 5
Cell Site Location Information Mobile switching centers may retain the location information in call detail records At least for a period of time (e.g., 24 hours) Authorities can track subscriber general movements by following sequence of towers contacted by the phone May also obtain last recorded location before signal or power lost Cell Site Location Information Most useful location information comes from initiation or receipt of a call or text A call data record (CDR) is kept for billing Yield historical i account of cell phone s locations Officers may also locate phone in real time while a call is in progress GPS devices receivers Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 6
Satellites Instead of Towers Global Positioning System Developed for military navigation; later opened to everybody else Three major components Satellites Ground stations Receivers Global Positioning System 32 Earth-orbiting solar-powered satellites 24 in operation, plus spares Limited life span about 10 years Equipped with up to 4 atomic clocks Orbits arranged so at least 4 (ideally 6) satellites visible anywhere, any time Send high-frequency, low-power radio signals Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 7
Global Positioning System Ten ground stations around Earth Monitor satellite signals and collect accuracy measurements Master control station in Colorado Determine if adjustments or updates needed Four large ground-antenna stations Send corrective data and commands to satellites GPS Receivers Equipped with quartz clocks constantly reset based on time signal from satellites Locate 4 or more (at least 3) satellites Calculate l distance to each Use that information to deduce receiver location Using trilateration In three-dimensional space 2-D or 3-D Fix 2-D Signals from 3 satellites Latitude and Longitude 3-D Signals from 4 or more satellites More accurate Lat/Long plus Elevation/Altitude Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 8
2-D Trilateration illustration If you re 625 miles from Boise where are you? 2-D Trilateration If you also learn that you re 690 miles from Minneapolis where might you be? 2-D Trilateration When you also learn you re 615 miles from Tucson do you know where you are? Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 9
3-D Trilateration 3-D Trilateration 3-D Trilateration Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 10
GPS Devices Portable Portable Navigation Devices Vehicle Outdoor Mobile phones Fixed Vehicle Marine Aviation Tracking Potentially Recoverable Data Device information Owner information Waypoints Home location Favorites Points of interest (POI) Last fix Routes/Journeys Track logs Deleted locations Paired Bluetooth devices Contacts Text messages Call logs Pictures Audio Documents Convergence Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 11
Questions? Don Mason Associate Director National Center for Justice and the Rule of Law 662-915-6898 drmason@olemiss.edu www.ncjrl.org Copyright 2011 National Center for Justice and the Rule of Law All Rights Reserved Page 12