Methods and systems for correcting distortions of audio transmissions are provided. In one embodiment, a method is provided that includes receiving an audio transmission that includes symbols. A first portion of the audio transmission including a first subset of the symbols may be identified and compared to an expected sequence having expected symbols. One or more differences may be determined between the first subset of the symbols and the expected symbols and a movement speed between a transmitter and a receiver of the audio transmission may be determined based on the differences. A second portion of the audio transmission may be identified including a second subset of the symbols in the second subset of the symbols may be corrected based on the movement speed between the transmitter and the receiver.

Methods and systems for correcting distortions of audio transmissions are provided. In one embodiment, a method is provided that includes receiving an audio transmission that includes symbols. A first portion of the audio transmission including a first subset of the symbols may be identified and compared to an expected sequence having expected symbols. One or more differences may be determined between the first subset of the symbols and the expected symbols and a movement speed between a transmitter and a receiver of the audio transmission may be determined based on the differences. A second portion of the audio transmission may be identified including a second subset of the symbols in the second subset of the symbols may be corrected based on the movement speed between the transmitter and the receiver.

A receiving apparatus includes: M receivers configured to receive signals based on sound waves propagating in water; M FIR filters configured to perform waveform operation on the signals received by the receivers; a combiner configured to combine output signals of the M FIR filters; and a filter coefficient calculation portion configured to calculate a tap coefficient of the M FIR filters so as to reduce an error of the output signals combined by the combiner. The M FIR filters have a tap length that is shorter than a delay spread that is a possible range between a time of arrival of a direct wave and a time of arrival of a delayed wave of the sound waves.

A receiving apparatus includes: M receivers configured to receive signals based on sound waves propagating in water; M FIR filters configured to perform waveform operation on the signals received by the receivers; a combiner configured to combine output signals of the M FIR filters; and a filter coefficient calculation portion configured to calculate a tap coefficient of the M FIR filters so as to reduce an error of the output signals combined by the combiner. The M FIR filters have a tap length that is shorter than a delay spread that is a possible range between a time of arrival of a direct wave and a time of arrival of a delayed wave of the sound waves.

In an approach for detecting and processing multiple audio signals simultaneously, an audiometric receiver system comprises a transmitter, wherein the transmitter comprises a digital signal processor, and wherein the digital signal processor comprises a quality check component, an amplifier or attenuator component, mixer component, a modulator component, and an encrypter component; and a receiver, wherein the receiver comprises a decrypter component, a demodulator component, a splitter component, and a second amplifier or attenuator component.

A device may include a processor, a receiver, and a transmitter. The receiver may be configured to receive a content signal. The transmitter may be configured to transmit the content signal. The transmitter may be configured to transmit an associated inaudible signal. The content signal, the associated inaudible signal, or both, may be transmitted to one or more electronic devices. Each of the one or more electronic devices may be configured with audio interfaces. The receiver may be configured to receive a respective message from each of the one or more electronic devices. Each respective message may be based on the associated inaudible signal. Each respective message may include a respective electronic device identifier. The transmitter may be configured to transmit one of the respective messages.

A device may include a processor, a receiver, and a transmitter. The receiver may be configured to receive a content signal. The transmitter may be configured to transmit the content signal. The transmitter may be configured to transmit an associated inaudible signal. The content signal, the associated inaudible signal, or both, may be transmitted to one or more electronic devices. Each of the one or more electronic devices may be configured with audio interfaces. The receiver may be configured to receive a respective message from each of the one or more electronic devices. Each respective message may be based on the associated inaudible signal. Each respective message may include a respective electronic device identifier. The transmitter may be configured to transmit one of the respective messages.

Provided are an ultrasonic human body communication method and a device thereof, the method including dividing serial information into blocks, and each information block includes modulation bits and index bits; each transmission frame is divided into multiple groups; performing an index modulation on the groups of each transmission frame, determining activated group sequence numbers; performing a digital modulation on the modulation bits of each information block, and mapping the digitally modulated modulation bits to activated groups; for the multiple information blocks processed in parallel, performing a parallel/serial conversion, a pulse shaping, and an ultrasonic conversion in sequence to obtain a transmission signal, and transmitting the transmission signal in a human body through a transmission frame; on a receiving node, receiving a received transmission signal propagated by the human body, and demodulating the received transmission signal to obtain the index bits and the modulation bits.

Provided are an ultrasonic human body communication method and a device thereof, the method including dividing serial information into blocks, and each information block includes modulation bits and index bits; each transmission frame is divided into multiple groups; performing an index modulation on the groups of each transmission frame, determining activated group sequence numbers; performing a digital modulation on the modulation bits of each information block, and mapping the digitally modulated modulation bits to activated groups; for the multiple information blocks processed in parallel, performing a parallel/serial conversion, a pulse shaping, and an ultrasonic conversion in sequence to obtain a transmission signal, and transmitting the transmission signal in a human body through a transmission frame; on a receiving node, receiving a received transmission signal propagated by the human body, and demodulating the received transmission signal to obtain the index bits and the modulation bits.

An acoustic transponder provides information related to the transponder when the transponder is receiving an acoustic interrogating signal. The transponder includes a power supply, an electronic circuit connected to the power supply, and one or more transducers receiving and emitting the acoustic signal. The electronic circuit includes a sequence generator. The transponder further includes an amplification and modulation unit, an extraction filter, and a suppression filter. The extraction filter is adapted to extract the received acoustic interrogating signal and suppress other signals prior to being input to the amplification and modulation unit which are configured to modulate the received acoustic signal according to a sequence generated by the sequence generator and to amplify the modulated signal. The suppression filter is adapted to suppress the received acoustic interrogating signal from the amplified and modulated signal. The amplified modulated signal is transferred through the one or more transducers of the transponder and/or through other transducer(s).