606 and communication hardware 656 may include a network interface and associated devices for communications with a wireless network, such as network interface cards, antennas, buses, switches, routers, modems, supporting hardware, and/or supporting software. The communication hardware 606 and communication hardware 656 may further include processing circuitry for causing transmission or handling receipt of signals to or from a network.

In addition to communication hardware 606 and communication hardware 656, an apparatus may further be configured to provide an input/output interface and receive an indication of user input. For example, an apparatus may comprise a display, keyboard, mouse, touch screen, microphone, speaker, and/or other input/output devices. The apparatus may further comprise software enabling a user to interact with the apparatus, including, for example, drivers, graphical user interfaces, web browsers, terminals, and/or the like.

The DAC 606 includes devices or circuitry embodied in either hardware or a combination of hardware, firmware, and software configured to produce analog audio signals from a digital input. The DAC 606 depicted in FIG. 6 may possess the capabilities of one or more of channel encoder 404, modulator 406, and/or spreading generator 408 depicted in FIG. 4. The DAC 606 may include input and output interfaces, power management components, and integrated circuits for processing of digital signals and preparation of analog signals with the desired properties. Likewise, the ADC 658 includes devices or circuitry embodied in either hardware or a combination of hardware, firmware, and software configured to produce digital audio signals from an analog input. The ADC 658 depicted in FIG. 6 may possess the capabilities of one or more of demodulator 410, spreading generator 412, and/or channel decoder 414 depicted in FIG. 4. The ADC 658 may include input and output interfaces, power management components, and integrated circuits for processing of analog signals and preparation of digital signals with the desired properties.

Speaker 610 and microphone 658 may be peripheral devices and associated hardware, software, and/or firmware components (e.g., amplifiers, drivers, and/or the like) for emitting and detecting sound waves. Speaker 610 and microphone 658 may have any range of response and sensitivity for various frequency spectra, and it will be understood that the IOS protocol may be configured with parameters chosen so that performance is maintained over a variety of models, qualities, and other properties of speaker 610 and/or microphone 658. For example, speaker 610 may have capabilities for emitting sounds in certain frequency ranges that may overlap with and/or go outside of human-detectable frequency ranges.

As noted above, apparatus 600 may optionally include DAC 608 and speaker 610. In examples in which apparatus 600 does not include a DAC 608 and/or a speaker 610, the apparatus 600 may be configured to transmit an encoded IOS token to a separate device, such as a television, that may perform digital to analog conversion and emit the sound corresponding to the IOS signal.

Example Operations

FIG. 7 is a block diagram illustrating an example process for IOS communication, in accordance with various aspects of the present disclosure. Example flowcharts are illustrated that contain operations implemented by various examples described herein. The operations illustrated in FIG. 7 may, for example, be performed by example system 100 depicted in FIG. 1, embodied by apparatus 600 and apparatus 650, which may be in communication with an external server or other devices. The operations described in connection with FIG. 7 may also be performed by other configurations or systems that differ from example system 100 described previously.

As shown by operation 710, an apparatus 600 includes means, such as processor 602, memory 604 and/or the like, for determining a series of symbols based on an input message. In some examples, each symbol from the series of symbols may represents a numerical (e.g., hexadecimal) value. In some examples, each symbol from the series of symbols may corresponds to a band-limited white noise tone, and each white noise tone may be orthogonal to each other band-limited white noise tone corresponding to each other symbol, as described previously in connection with FIG. 2. The tones may be orthogonal in the sense that, in an audio signal containing a mixture of two orthogonal tones, the orthogonal tones do not interact with each other. Practically speaking, this means that multiple symbols may be superimposed (e.g., emitted simultaneously) without negatively affecting the ability to detect both of the superimposed symbols.

In some examples, the known symbols may form an “alphabet” of symbols that may be constructed within the specifications of the IOS protocol for the given latency, inaudibility, and detectability requirements. Each symbol from the “alphabet” may correspond to a numerical value from a restricted range of values, allowing a system of tokens to be constructed from series of numerical values from the restricted range. A portion of the symbols from the “alphabet” may be reserved for control functions, such as a start symbol to indicate the beginning of a token, end symbol for the end of a token, error correction symbols, and/or the like. Other symbols may carry payload data that may be interpreted by the device receiving the message.

As shown by operation 720, an apparatus 600 includes means, such as processor 602, memory 604 and/or the like, for generating a sub-token comprising each symbol from the series of symbols. The processor 602 may look up the band-limited white noise representation of each symbol from the series of symbols and arrange the sequence of band-limited white noise tones into a sub-token. Within the structure of the sub-token, each symbol may overlap in time with at least one other symbol. For example, as shown in FIG. 2, a sub-token may include six overlapping symbols, the first symbol overlaps with the second symbol, the second symbol overlaps with the first and third symbols, and so on. The duration of the overlap may be decided by the duration of each symbol and the overlap delay, which may be configurable and selected to optimize latency, inaudibility, and detectability. For example, in the application of consumer home televisions emitting signals detectable by mobile phone devices in the same room, symbols of 0.25 s duration with an overlap delay of 0.125 s (for a sub-token of six symbols and tokens comprising three sub-tokens).

In some examples, the sub-token may be prepared together with one or more additional sub-tokens that make up a token. The sub-tokens may be independent, or overlapping as depicted in FIG. 5. In various examples, encoding tokens with overlapping sub-tokens, as shown in FIG. 5, may reduce latency.

As shown by operation 730, an apparatus 600 includes means, such as processor