Patent ID: 8837257

Claim:
A computer-implemented method for generating a modulated acoustic carrier signal for wireless transmission from a speaker of a transmit device to a microphone of a receive device, comprising: converting a message to binary data; modulating one or more selected frequencies for one or more acoustic carrier signals based on the binary data to generate one or more modulated acoustic carrier signals; filtering the one or more modulated acoustic carrier signals to remove any unintended audible harmonics created during modulation, including to reduce audibility of the modulated acoustic carrier signal, the filtering further including; equalizing the modulated acoustic carrier signal to pre-compensate for known degradations that will occur further along a signal path; and setting a level of the modulated acoustic carrier signal for an intended application; storing the modulated acoustic carrier signal in a buffer for subsequent output and transmission by the speaker as audio over air for receipt by the microphone of the receive device; and, in response to the microphone of the receive device receiving the one or more modulated acoustic carrier signals, demodulating the one or more modulated acoustic carrier signals to recover the binary data using an acoustic modulation protocol by: receiving the one or more modulated acoustic carrier signals as blocks from one or more buffers; filtering the one or more modulated acoustic carrier signals to eliminate out-of-band signals and improve signal-to-noise ratio; dynamically adjusting a gain of the one or more modulated acoustic carrier signals to provide a substantially constant power level for the one or more modulated acoustic carrier signals; and performing a Rasterized Digital Fourier Transform (RFT) that is based on a Goertzel frequency transform in combination with an adjustable Goertzel window length to increase frequency discrimination and to identify frequency components of the one or more modulated acoustic carrier signals.