Methods and devices for transferring data using sound signals

One or more tangible, non-transitory computer-readable media storing instructions that, when executed by one or more processors of a media playback system, cause the media playback system to perform operations comprising:

• receiving sound comprising a block of data modulated on an intermittent carrier signal;
• sampling the received sound to generate a sampled data stream;
• and
• demodulating the sampled data stream by:
• demodulating a portion of the sampled data stream corresponding to a first duration in which the intermittent carrier signal is present, and
• disregarding a portion of the sampled data stream corresponding to a second duration in which the intermittent carrier signal is not present.

A playback device comprising:

• an electroacoustic transducer configured to generate audio signals;
• a computer-readable medium storing program code;
• and
• a processing system;
• wherein the program code, when executed by the processing system, causes the playback device to:
• encode a block of data into a plurality of symbols to be transmitted,
• modulate the symbols onto a first intermittent carrier signal to generate modulated data, and
• transmit, using the electroacoustic transducer, first and second subsets of the modulated data, wherein the first subset of the modulated data is transmitted while the electroacoustic transducer is outputting an audible signal, wherein the second subset of the modulated data is transmitted while the electroacoustic transducer is not outputting the audible signal, and wherein the first and second subsets of the modulated data are transmitted by:
• transmitting a portion of the first or second subset of the modulated data for a first duration, and
• pausing transmission for a variable second duration, wherein the variable second duration is based on a characteristic of the electroacoustic transducer.