Offender tracking consists of a Small tracking unit worn on the belt or ankle.
it uses the technology of Global positioning system (GPS) to record the wearer's movements.
This data is fed to a server which matches movements with places.
Some offenders are restricted to an area around their home.
if they move outside that area, this is reported by e-mail to the police.
Some offenders are forbidden to enter certain areas.
if they go there, this is reported automatically to the police The system also contains details of crimes.
if an offender is near the
scene of a crime at the right time, a report is sent directly to the police .