Acoustic modulation protocol

A system, comprising:

• a receive device having a microphone;
• and
• a transmit device having a processor, memory and a speaker, the processor configured to execute an acoustic modulation protocol that is configured to:
• convert a message to binary data;
• modulate 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;
• filter the one or more modulated acoustic carrier signals to remove any unintended audible harmonics created during modulation;
• equalize the one or more modulated acoustic carrier signals to pre-compensate for known degradations that will occur further along a signal path;
• and
• store the one or more modulated acoustic carrier signals in a buffer for subsequent output and transmission by the speaker for receipt by the microphone of the receive device.

An executable software product stored on a computer-readable medium containing program instructions for generating a modulated acoustic carrier signal for wireless transmission from a speaker of a transmit device to a microphone of a receive device, the program instructions for:

• 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;
• equalizing the modulated acoustic carrier signal to pre-compensate for known degradations that will occur further along a signal path;
• setting a level of the modulated acoustic carrier signal for the intended application;
• and
• storing the modulated acoustic carrier signal in a buffer for subsequent output and transmission by the speaker.

A method of demodulating one or more modulated acoustic carrier signals sent over air by a transmit device and received by a microphone of a receive device, the method comprising:

• 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) based on a Goertzel frequency transform to identify frequency components of the one or more modulated acoustic carrier signals.