RFID Reforms Prison Management
An inmate-tracking system being used at a California prison warns of a potential escape. It may also reduce prison violence and safeguard employees.
July 1, 2002 - The inmate population in the United States is now just over 1.4 million, according to the Bureau of Justice Statistics. How do prisons keep track of all these criminals? The same way they have for decades: By counting heads five to eight times a day. That means when there is an escape, it often goes undetected until the next head count, which can give the prisoner valuable time to get away.
Technology Systems International (TSI), a Scottsdale, Ariz., company founded in 1994, would like to change that by using radio frequency identification to track inmates in real time, providing an early warning when someone attempts to break out. Calipatria State Prison, a maximum-security facility tucked in the desert in the southeast corner of California, has been testing the system since last October. It foiled at least one escape, identified prisoners involved in a riot and provided other benefits.
Here's how the system works. A transmitter, which looks like a large industrial wristwatch, is strapped to the wrist of each of Calipatria's 325 level-one (low-security) inmates. The device holds a 900 MHz RFID transmitter with a battery that sends out a signal every couple of seconds. The transmitter is housed in a tamperproof casing and strapped with screws with tamper-resistant covers. If the band is cut or a prisoner manages to slide the band off, an alarm is automatically triggered at a central monitoring station.
Readers with antennas are set up around the prison yard and throughout the interior of the building. Calipatria has about 60 readers, which pick up signals from every transmitter in the facility. At least three readers may pick up a signal from each inmate, but its usually many more to provide redundancy in the system. The signals are sent to a collector node, which calculates the person's location to within a few feet and puts a time of arrival stamp on the information and forwards it to computers running TSI's control software, which is used to establish the conditions for alerts. The system can handle up to 24,000 units, according to TSI. The readers can process hundreds of signals virtually simultaneous, because the signals are transmitted up so quickly.
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| Calipatria prison |
Technology Systems International (TSI), a Scottsdale, Ariz., company founded in 1994, would like to change that by using radio frequency identification to track inmates in real time, providing an early warning when someone attempts to break out. Calipatria State Prison, a maximum-security facility tucked in the desert in the southeast corner of California, has been testing the system since last October. It foiled at least one escape, identified prisoners involved in a riot and provided other benefits.
Here's how the system works. A transmitter, which looks like a large industrial wristwatch, is strapped to the wrist of each of Calipatria's 325 level-one (low-security) inmates. The device holds a 900 MHz RFID transmitter with a battery that sends out a signal every couple of seconds. The transmitter is housed in a tamperproof casing and strapped with screws with tamper-resistant covers. If the band is cut or a prisoner manages to slide the band off, an alarm is automatically triggered at a central monitoring station.
Readers with antennas are set up around the prison yard and throughout the interior of the building. Calipatria has about 60 readers, which pick up signals from every transmitter in the facility. At least three readers may pick up a signal from each inmate, but its usually many more to provide redundancy in the system. The signals are sent to a collector node, which calculates the person's location to within a few feet and puts a time of arrival stamp on the information and forwards it to computers running TSI's control software, which is used to establish the conditions for alerts. The system can handle up to 24,000 units, according to TSI. The readers can process hundreds of signals virtually simultaneous, because the signals are transmitted up so quickly.
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