The basic concept is to be able to identify how far away (signal strength) the transmitter is. The receiver can then go into alarm mode if the transmitter wanders too far away. Purposes abound... Kids too far from home, dog ran away, your previous safe just got stolen when the quests left... you get the picture. The distance I was hoping to achieve was upwards of 2 kms (or 1.5 miles) with the ability to reduce that range within software.