A method for detecting the proximity of a signal source using wireless systems is contemplated in which a wireless mobile device wirelessly receives packets from a signal source and determines a received signal strength for each packet. The wireless mobile device may store information based upon the received signal strength for each packet, and calculate from the information stored for all the packets, a current path loss value corresponding to a current distance from the wireless mobile device to the signal source. The wireless mobile device may then determine whether the current distance is sufficient to be an enabling condition such as tap, for example, for a data transfer or a transaction between the wireless mobile device and the signal source.