Electronic Monitoring

Radio Frequency

Radio Frequency (RF) is a tool used as part of the California Department of Corrections and Rehabilitation, Division of Adult Parole Operations Electronic In-Home Detention (EID) program. The EID program is used to monitor offender compliance with imposed curfews as an enhancement to supervision and an alternative sanction to incarceration.

How Does Radio Frequency Technology Work?

The RF equipment includes a device worn on the offender’s ankle which electronically tethers to a base unit inside the offender’s residence. The device is in communication with the base unit using radio signals that determine if the offender is in proximity.

The RF equipment is used to monitor offenders with an established curfew imposed as a Special Condition of Parole. Curfew hours are set in the day or night, during which time the offender must remain inside his or her residence.

RF technology is used for:

  • Alternative Custody Program participants
  • Parolees needing enhanced supervision
  • Alternative sanction for parolees committing minor parole violations

Global Positioning System Technology

Global positioning system (GPS) technology uses radio signals to communicate with satellites orbiting the earth. GPS technology locates a device by measuring the distance between multiple satellites and the device to determine the offender’s location.

GPS technology is used for:

  • Sex Offenders
  • High Risk Gang Offenders
  • Special Circumstance Cases

Why GPS?

In addition to meeting the requirements of specified California statute, GPS has proven to be an effective tool used in supervising offenders who are at high risk of re-offending and where knowledge of their whereabouts is a high priority for maintaining public safety. GPS data can be used to map geographic locations assisting the parole agent’s ability to provide more intensive parole supervision of high risk offenders.

The Value of GPS Technology


Information gathered that may be shared with local law enforcement for investigative purposes.

Patterns and Trends

Mapping the GPS data over time gives a picture of the parolee’s travel patterns and places frequented.  The GPS can also be used to monitor special conditions of parole such as curfews, requirements to stay away from victims and requirements to stay away from other specific locations.    

Crime Scene Correlation

Compares GPS data to law enforcement crime data to determine if the offender can be excluded or included as a possible suspect in a crime.  The Crime Scene Correlation tool is made available to local law enforcement agencies requesting access to the GPS database.