Abstract: A mobile device that generates and transmits a human-inaudible acoustic signal, which encodes a symbol sequence representing a binary message, for delivery as audio content, is disclosed. The mobile device encodes the binary message into a sequence of symbols that are each associated with frequency characteristics and generates and transmits the human-inaudible acoustic signal, based on the frequency characteristics of the symbols. A further mobile device that receives and decodes a human-inaudible acoustic signal, which encodes a symbol sequence representing a binary message, embedded within audio content, is disclosed. The mobile device repeatedly performs a frequency domain transformation of samples of the signal to generate a symbol sequence, and performs error correction decoding upon the symbol sequence to determine the validity of the symbol sequence.

Abstract: A mobile device that generates and transmits a human-inaudible acoustic signal, which encodes a symbol sequence representing a binary message, for delivery as audio content, is disclosed. The mobile device encodes the binary message into a sequence of symbols that are each associated with frequency characteristics and generates and transmits the human-inaudible acoustic signal, based on the frequency characteristics of the symbols. A further mobile device that receives and decodes a human-inaudible acoustic signal, which encodes a symbol sequence representing a binary message, embedded within audio content, is disclosed. The mobile device repeatedly performs a frequency domain transformation of samples of the signal to generate a symbol sequence, and performs error correction decoding upon the symbol sequence to determine the validity of the symbol sequence.