State and federal correction agencies are staggering under the cost of incarcerating the nation's 1.6 million inmates -- more than all personnel on active duty in the U.S. armed forces. And the number is growing. The Bureau of Justice Statistics estimates that by the year 2005 the prison population will be 3.5 million. If the underlying causes are not addressed, that number could be even higher.

Since the Supreme Court ruled that federal prisons cannot exceed 125 percent capacity, and state prisons 117 percent -- limits reached by most in the 1980s -- the criminal justice system has been forced to release increasing numbers of inmates before their sentences are up to make room for dangerous criminals. In the past, those on early release were generally placed in house-arrest programs, and their presence in the home electronically monitored. Nonviolent, low-risk offenders, allowed out to work at day jobs, had to be "clocked in" at hours prescribed by the supervising agency.

ELECTRONIC MONITORING

Monitoring programs are considerably cheaper than incarceration. They also enable working offenders to begin paying restitution to victims and reimbursing the state for the cost of monitoring. Also, since 68 percent of incarcerated first-timers end up back inside, placing them in monitoring programs instead of in cells with habitual criminals may help reduce recidivism among this group.

Conventional house-arrest electronic monitoring systems use a miniature transmitter locked around the offender's ankle. The device communicates with a modem attached to the telephone. When the individual comes home, the transmitter instructs the modem to send a "time-in" message to a central monitoring facility. If the subject goes beyond, say, 150 feet from the house, the modem automatically transmits a "time-out" message. The information is relayed to the supervising agency, where it goes into a database of case files. Correction or parole officers can bring up a file at any time to see if the subject is abiding by the prescribed home-confinement hours.

However, conventional house-arrest monitoring does not track the movements of individuals outside the home. "The problem with these systems," said former Florida governor and U.S. drug czar Bob Martinez, "is that if you're not home, no one knows where you are." With growing pressure to put more offenders on electronic monitoring, the need is a system that enables supervising agencies to know where the offender is at all times.

GPS TRACKING

Pro Tech Monitoring Inc., a company headed by Martinez, developed the Satellite Monitoring and Remote Tracking (SMART) system, which combines GIS, GPS, cellular phone and Internet technologies for 24-hour tracking. The person under supervision wears a 3.5-ounce, tamper-proof ankle bracelet electronically "leashed" to a small, portable tracking device (PTD) carried in a waist pack, handbag or briefcase. The PTD contains the microprocessor, GPS receiver and cellular/land-line communication system.

According to Martinez, the rules of behavior can be programmed into each device from a desktop PC. Constraints can include boundaries set up by geography and time -- where the subject is supposed to be at specific hours of the day and night, routes to and from work or rehabilitation classes, restricted areas of the community and the distance in feet the individual may be from the device. This can be up to 1,000 feet, depending on the type of work the person does. If the specified distance is exceeded for more than a few minutes, the device notifies the control center of the violation. The police are then directed to apprehend the person.

If a guideline is violated, the device warns the subject with an alarm, a digitized voice and a liquid crystal display message. A violation not corrected within the required time, usually minutes, triggers a call to the control center via cellular phone. When the subject is home, the device automatically switches communications from cellular to the home telephone. "The device is like a warden