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Location Monitoring

Location Monitoring in the Central District of California supervises approximately 250 offenders in seven counties consisting of 40,082 square miles.  The district utilizes several methods of monitoring, including Radio Frequency (RF), Voice/ Video Recognition, Global Positioning Satellite (GPS) and Field Alcohol testing units.

Radio Frequency (RF) utilizes a field monitoring device attached to the participant’s telephone line, and a transmitter attached to the participant’s body. The non-removable transmitter is shock and water resistant.  Using radio frequency technology, the receiver monitors the presence or absence of an offender’s transmitter within a specified range. This system is designed to alert an officer when a participant deviates from a pre-approved schedule or tampers with the electronic monitoring equipment. 

Voice /Video Recognition are systems of monitoring used for participants who are unable to wear a transmitter because of documented health reasons.  Voice recognition uses voice-print, a type of biometric authentication, to confirm the identity of an individual.   Video recognition uses a digital camera to send digitized images of the participant’s face to a remote monitoring center. This is an interactive system utilizing a residential telephone line, and action by the participant is required in order for the equipment to function properly.  Random verification is made during curfew hours, including late night and early morning hours.

Global Positioning Satellite (GPS) records the participant’s location, utilizing satellites and cell phone towers.  This information is available through a web-based case management system which includes a mapping program.  The GPS system can be programmed to alert the Location Monitoring Officer of “key events,” including entering or leaving specific areas and deviations from approved schedules and tampers.

There are currently three types of Alcohol Field testing units.  Voice recognition utilizes a hand-held monitoring device that detects the presence of alcohol through an individual’s deep lung breath sample. It incorporates biometric voice verification and fuel cell alcohol testing technology.  Video identification also uses a deep-lung alcohol testing system to report blood alcohol concentrations.   A camera sends digitized test results and the participant’s facial image to a remote monitoring center.   Transdermal alcohol testing measures the concentration of alcohol present in perspiration.  The equipment monitors a variety of tampers as well as the presence or absence of an offender’s transmitter within a specified range.    

The Central District of California Location Monitoring Program utilizes the full array of location monitoring technologies which can provide functionality to monitor the location and compliance of a defendant/offender at their residence and throughout the community.  The program emphasizes the use of these technologies to lower costs of incarceration and to serve as one of many supervision tools that will assist an officer in improving community safety.