Abstract: A body worn transmitter periodically transmits a coded rf signal from a rolling code generator, which is received by a base unit at the location where a person is confined, which base unit has a rolling code generator synchronized to produce the same random code signal for comparison. If proper coded signals are not received, a report is sent via telephone to a remote monitoring station. The body worn transmitter is designed to detect and defeat attempts at removal.

Abstract: A body worn transmitter periodically transmits a coded rf signal from a rolling code generator, which is received by a base unit at the location where a person is confined, which base unit has a rolling code generator synchronized to produce the same random code signal for comparison. If proper coded signals are not received, a report is sent via telephone to a remote monitoring station. The body worn transmitter is designed to detect and defeat attempts at removal. The body worn transmitter is also used to detect the presence of a person at a particular location. By programming the time of rf transmissions, a large number of body worn transmitters can be monitored at a given location.