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Electronic Bracelets

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Title Electronic Bracelets
Edited by GMV
Level Basic
Year of Publication 2011
Logo GMV.png

The Electronic Bracelets are an example of personal tracking products, meant to control prison populations, house arrests or protecting victims of crimes.

These systems are designed to serve as alternative to prison, as well as to monitor post-sentence behaviors for some sort of crimes, such as child molesters or other types of sex offenders.

Product Description

The most obvious application of electronic bracelets is the tracking of persons charged with a crime that requires home monitoring.

Electronic bracelets are becoming a common alternative to imprisonment, for selected probationers, providing a command and control platform, as well as an extra layer of supervision to the community at large.[1]

This system consists in the bracelet equipment applied in the offender and by a secure command and control website, operated by the police officers, which has the capability to display offender’s position and keep a registry of activities.

The Electronic Bracelets systems usually offer the following capabilities:

  • Home facilities geofence: In case an offender leaves his or her home at a time not authorized by a judge, an alert (auditory and visual) indicates that the probationer is out of the defined geofence.
  • Prevent destruction or removal: In case the bracelet is removed or destroyed, a sensor will indicate this violation and an alert is raised in the command and control website.
  • Track an evasion: In case the offender steps away from the defined geofence, an arrest warrant is issued and the suspect can be easily tracked.
  • Grant a restrained freedom: In some situations some offenders can continue to carry their jobs within a defined geofence, without issuing an alert.
  • Detection of infractions: These systems can also be programmed to detect speeding situations, when the offenders are allowed to drive.
  • Victims protection: The geofence mechanism can also be used to detect if the offender enters in forbidden areas, for instance in domestic violence or child molester situations. In domestic violence case, if the offender happens to enter in an exclusion geofence, the police can act and notify the victim about the situation.[2] Vicinities of schools can also be defined as exclusion zones for child molesters, forbidden to be nearby these facilities.

The applications for which electronic bracelets are used are considered as safety critical applications.

The accuracy required by these applications is low. The current accuracy provided by civilian GPS is enough for these applications. Availability, however, can be reduced due to urban environments, but it can be improved with the Assisted-GPS technology.

Product Characterization

Electronic bracelets are now moving from RFID to GNSS technology, which grants a more reliable product in terms of tracking needs. Some of these systems integrate the GNSS technology with other legacy technologies.

The GNSS bracelet devices are labeled in two different types, the active and the passive units[3]:

  • Active units: These devices collect the offenders data and position in real time, leaving little chance for the tracked person to trespass the geofence. The GNSS devices send the data to the command and control website which allow the police officers to get the location of the offender immediately.
  • Passive units: These devices collect the offender’s data that is stored throughout his daily activities. The person tracked connects the unit daily in a docking station. This station is plugged into a power outlet, to recharge the device, and to the offender’s home phone line. The police officers then evaluate the data through the command and control website to verify where the offender was through the course of the day.

The offender’s position, direction, traveling speed, time of day and date can be all monitored, for both types of units, allowing for the system to pinpoint positions on a map.

Product Examples

The following Manufacturers are producing GNSS Electronic Monitoring Devices and application platforms for house arrests[4]:



  1. ^ The Electronic Monitoring Program - 2010 Fact Sheet - The Massachusetts Probation Service
  2. ^ GPS bracelets would deter domestic violence
  3. ^ eHow.com How Does a GPS Ankle Bracelet Work?
  4. ^ GPS practice and fun site - Offender tracking