a system and method for determining if a first and second device are co - located includes first and second sensors for receiving a sample signal . each sensor is coupled to the first and second devices . the first and second devices each responsively generate a first and second signal representing the sampled signal . also included is a transmission device located at the first device for transmitting the first signal to the second device and a receiving device located at the second device for receiving the first signal from the first device . finally , a signal analysis device determines if the first and second devices are co - located .