Abstract: A display system is disclosed for use in connection with a beacon tracking receiver. The display system provides both audible and visual displays for use in locating a source of radio transmission. The display includes an audible tone signal to indicate the reception of a desired signal and with a frequency indicative of the distance to the transmitter. The visual display includes the direction as well as the distance to the transmitter. Also disclosed is a new switching means for use in activating the transmitter of a beacon tracking system.

Abstract: A radio frequency transmitter is hidden within a packet of currency which may be mingled with other currency packets in the cash drawer of a bank, convenience store or other such commercial institution. The transmitter is automatically activated by unauthorized removal from the cash drawer or other place of safekeeping. The signals from the transmitter activate alarms in one or more receivers located in police vehicles in the area. The receivers employ phase comparison techniques to indicate relative direction and distance to the transmitter thereby facilitating apprehension of the possessor of the packet.