Patent ID: 7394364

Claim:
A monitoring system for movable targets comprising a plurality of target-borne transmitters, each transmitter having a case; attachment means for attaching the case to the target; a radio-frequency signal generator housed within the case and adapted to generate and repeatedly to transmit a coded signal at a selected radio frequency and separated by a selected prime number time interval; a transmitter antenna coupled to the signal generator; and a battery within the case and coupled to signal generator; and a base unit adapted to monitor the transmitters, the base unit having a housing having an interior and a face; signal detection means within the housing for listening at the selected frequency and prime number time interval for each transmitter; and receiving the coded signals from the transmitter signal generator transmitting at its selected prime number time interval; a database within the housing and containing information about each target and the transmitter's selected prime number time interval; processing means within the housing and adapted to detect coded signals from the signal detection means; process the coded signals to update the database means with information about the transmitter attached to each target; and sound an alarm for an out-of-range condition of any transmitter; operator interface means for providing an operator with control of the processor means and information about each target; and power means for providing power to the base unit.