Detection of short distance wireless transmitted audio

With the advance of short distance wireless technologies, it becomes popular to include FM transmission capability to mobile devices such as hands-free car kits, cellular phones with hands-free features, and MP3 players so that in addition to playing audio signal through the on-device loudspeaker, they can relay audio signal to other audio system to utilized their superior audio quality. Traditionally, the switch between the on-device loudspeaker and the FM transmitter is done manually. This paper proposes an automatic and switching algorithm which leverages the AEC capability already exists in many of these mobile devices. The algorithm detects the presence of audio through FM channel and switches off the on-device loudspeaker, which adds to user convenience and power saving efficiency.