Abstract: A method for determining the location of a mobile device in a vehicle may include the transmission by one or more speakers of the vehicle of a sound signal having predetermined characteristics. The mobile device may include the capability to recognize the sound signal based on methods to identify a sound signal having the predetermined characteristics. In some aspects, the mobile device may incorporate software having a specific filter that is matched to the characteristics of the sound signal transmitted by the speakers. The mobile device may also include software configured to disambiguate effects of multi-path scattering, reflection, and attenuation of the signal through the vehicle cabin. The vehicle may include software to generate the sound signal and to adjust the sound signal characteristics for position-dependent signal fading, frequency dependent signal fading, and high amplitude audio interference.

Abstract: A system includes a plurality of transmitters, in which each transmitter is configured to transmit an ultrasonic acoustic signal and at least one ultrasonic acoustic signal is a modulated ultrasonic acoustic signal. The system also includes a mobile device comprising a processor, a receiver, and instructions stored on a non-transitory memory, so that when the instructions are executed by the processor, the instructions cause the mobile device to receive the ultrasonic acoustic signal, calculate a position of the mobile device based upon one or more characteristics of the ultrasonic acoustic signals, and demodulate the modulated ultrasonic acoustic signal to obtain an information data stream.