How GPS Works

You've probably heard about GPS before, but you may not know how it actually works. Here's a brief explanation.

GPS stands for Global Positioning System. GPS was developed by the U.S. Department of Defense as a precise navigation system for military applications, but has since been opened up to the public.

Twenty-four GPS satellites orbit the earth, constantly emitting radio signals. The satellites are positioned in space so that at least four are visible from any point on earth, at any time. These satellites are the foundation of GPS. Because these GPS satellites constantly "rain" signals down on the earth, anyone with a "bucket" or GPS receiver can "catch" them. Three people could have GPS tracking devices or three billion. It makes no difference.

A GPS receiver needs to "know" where the satellites actually are in order to calculate the receiver's location. This isn't particularly difficult because the satellites travel in very high and predictable orbits. The GPS receiver simply stores information regarding the satellites' position at any given time. Things like the pull of the moon and the sun do change the satellites' orbit very slightly but the Department of Defense constantly monitors their exact positions and transmits any adjustments to all GPS receivers as part of the satellites' signals.

When a GPS receiver locates and "catches" GPS signals, it measures how far away it is from each of at least four separate satellites. By calculating several locations over time, the GPS receiver can also compute speed and direction of travel.

iSECUREtrac takes this technology several steps further by combining communication networks, both landline and wireless, with web-based management software. The company also incorporates several sub-systems to detect, record and report non-compliance and any attempts at monitoring circumvention.

iSECUREtrac GPS systems record location points several times a minute. These devices contact the iSECUREtrac monitoring center at regular intervals and "tell" iSECUREtrac's computers where the monitored individual is, where he's been since the last contact and whether or not he is in compliance with pre-established supervision parameters. The systems then place the updated information on the iSECUREtrac electronic management reporting website so that corrections personnel can check the individual's location and status. Supervising officers can also create geo-fences or boundary zones where the individual is prohibited from going (e.g., elementary schools, spouse's residence, known gang hangouts, etc.) or where his presence is required (e.g., his residence, place of employment, counseling offices, etc.). These boundary zones are more commonly referred to as inclusion or exclusion zones. If the offender violates these zones, the supervising officer can elect to be notified.

Phone line is NOT required for GPS equipment to function.

Information is courtesy of our equipment supplier, iSECURETrac.