Mobile device locator

An audio system for a vehicle, the audio system being configured to transmit an acoustic signal for determining the location of a mobile device in a vehicle cabin and comprising:

• an audio processor configured to output a first audio signal to a first of a pair of stereo speakers and a second audio signal to a second of a pair of stereo speakers;
• a detection pattern generator;
• a vehicle speed sensor input configured to receive a vehicle speed value;
• wherein the detection pattern generator is configured to generate a first acoustic detection pattern and a second acoustic detection pattern, the first acoustic detection pattern and the second acoustic detection pattern being mutually orthogonal;
• and wherein in response to the vehicle speed value exceeding a predetermined threshold, the audio system is configured to combine the first detection pattern with the first audio signal and combine the second detection pattern with the second audio signal and to output a first acoustic signal comprising the first acoustic detection pattern and the first audio signal via a first of a pair of stereo speakers and a second acoustic signal comprising the second acoustic detection pattern and the second audio signal via a second of a pair of stereo speakers.

A method of determining the position of a mobile device in a region of a vehicle cabin, the mobile device comprising a speaker and a microphone, the vehicle cabin comprising at least two speakers, the method comprising:

• detecting by the mobile device microphone first and second acoustic signals respectively transmitted via the first and second speaker, the first and acoustic signals comprising a respective first detection pattern and a second detection pattern, wherein the first detection pattern and the second detection pattern are mutually orthogonal;
• generating a signal indicating an error condition in response to a signal strength of the detected patterns being below a predetermined threshold;
• comparing the detected first and second acoustic signals with the respective predetermined first and second detection patterns and outputting a respective first matched acoustic signal and a second matched acoustic signal;
• determining a location of the mobile device within a region of the vehicle cabin based on the time difference of arrival of the first matched acoustic signal and the second matched acoustic signal;
• and
• setting the mode of operation of the mobile device dependent on the location of the mobile device.