Abstract: A personnel monitoring system includes a transmitting or transponding unit that is worn or carried by the individual being monitored. This transmitting or transponder unit periodically, or upon request, transmits a uniquely encoded signal that identifies the person being monitored, as well as information about the condition or activities of the person being monitored. Such condition or activites are sensed by sensors, coupled to the transmitting unit, that monitor selected body functions or parameters, such as heart rate, amount of skin perspiration, muscle movement, and the like. The monitoring system also includes a field monitoring device, or FMD, that is positioned near the person being monitored (or at a location where the person being monitored should be found). The FMD receives, processes, and stores the periodic or requested signals transmitted from the transmitting unit as directed by a program stored in a factory-removable and replaceable memory pack.