US Patent 10254383 Mobile device indoor navigation

Mobile device positioning employs various forms of audio signal structures and detection methodologies. In one method, detection of an audio signal from a first source enables construction of a signal to facilitate detection of an audio signal from another source. Signals detected from these sources enable positioning of the mobile device receiving those signals. Another method forms audio signals transmitted from audio sources so that they have parts that add constructively and parts that differentiate the sources to enable positioning. Another audio signal based positioning method adaptively switches among positioning methods so that positioning remains operative as a mobile device moves toward and away from the sources. Another method tracks positioning history, evaluates it for errors and performs error mitigation to improve accuracy. Various other positioning technologies are detailed as well.