OFDM-based acoustic communications system

摘要

Disclosed is an orthogonal frequency division multiplexing (OFDM)-based acoustic communications system. At an acoustic transmitting end, original data is modulated through channel coding into an acoustic signal of a data frame formed by multiple OFDM symbols and the acoustic signal is transmitted through a loudspeaker; at an acoustic receiving end, after a microphone receives the acoustic signal, and the acoustic signal is restored to the original data through demodulation and channel decoding. In a communication process, symbol synchronization is implemented through pilot information, and data frame synchronization is implemented in a manner of inserting baker codes, thereby simplifying processing, having a low bit error rate, improving acoustic communication efficiency, promoting development of acoustic communication, and having a good application prospect.

主权项

1. An orthogonal frequency division multiplexing (OFDM)-based acoustic communications system, comprising an acoustic transmitting end and an acoustic receiving end, wherein the acoustic transmitting end comprises a channel coding module, a signal modulation module, a D/A conversion module, and a loudspeaker that are connected in sequence; the acoustic receiving end comprises a microphone, an A/D conversion module, a signal demodulation module, and a signal decoding module; the channel coding module is configured to receive original data; the signal decoding module is configured to output the original data; and data transmission is performed between the loudspeaker and the microphone through a communications channel of less than 24 kHz,
the channel coding module comprises a first BCH coding unit, an interleaving unit, and a second BCH unit that are connected in sequence, to extend the original data to obtain extended data; the channel decoding module comprises a first BCH decoding unit, a de-interleaving unit, and a second BCH decoding unit, to restore the extended data to the original data; the signal modulation module modulates the extended data based on OFDM, divides a channel into multiple orthogonal sub-channels, converts an extended data signal into concurrent low-speed sub-data streams, and modulates the sub-data streams onto each sub-channel for transmission, and comprises a symbol mapping unit, an IDFT unit, and a signal extension unit that are connected in sequence, wherein the symbol mapping unit receives the extended data output by the channel coding module, and the signal extension unit outputs a digital voice signal to the D/A conversion module; and the signal demodulation module demodulates the received digital voice signal based on the OFDM, divides one channel into multiple orthogonal sub-channels, converts the digital voice signal into extended data, and demodulates the extended data onto the converted channel for transmission, and comprises a DFT unit, a synchronization capturing unit, and a symbol inverse-mapping unit that are connected in sequence, wherein the DFT unit is configured to receive the digital voice signal output by the A/D conversion module, the symbol inverse-mapping unit outputs the extended data to the signal decoding module, and if failing in capturing a data signal, the synchronization capturing unit returns a feedback to the DFT unit through a sliding unit.