Division of Adult Parole Operations (DAPO)

How GPS Monitoring Works

GPS around a globeGlobal Positioning System (GPS) monitoring works due to the triangulation of satellites orbiting the earth. Twenty-four satellites are used in all.

To "triangulate" means that a GPS receiver measures distance using the travel time of radio signals. When a user's GPS ankle unit reads the signals sent to it by the satellites, these signals can provide information as to the wearer's location, speed of movement and direction of movement.



GPS basic system

Active VS Passive GPS Measuring

GPS deviceActive GPS transmits its location at near real-time intervals and can include immediate alert notifications.

Passive GPS transmits its location at set intervals and alert notifications are usually received the next day.



Use of GPS Data

GPS overall systemCrime Scene Correlation
GPS Offender Data
Crime Data from Law Enforcement
Comparing GPS Data with Crime Data
Automatic notification of "hits" via e-mail and other means
Intelligence Value
Identifying Associations
Investigative Tool
Geographic Information Systems (GIS)