US Patent 7664462 Recovery system with De-queue logic

A recovery system with repeating communication capabilities. The system includes a station configured to send an activation message, at least a first “primary” remote transmitting unit responsive to the station and configured to transmit the activation message and at least a one “secondary” remote transmitting unit. That unit includes a receiver which receives the activation message, a transmitter for transmitting the activation message, and a controller responsive to the receiver and controlling the transmitter. The controller is programmed to transmit the activation message and then automatically stop transmission of the activation message after a predetermined time period unless the activation message is again received.