Communication method of underwater digital voice

Abstract

The invention discloses a communication method of underwater digital voice and relates to a communication method. The communication method comprises the following steps of: at a communication transmitting end, sampling input simulated voice by using an analogue to digital (A / D) converter so as to obtain digital voice, performing mixed excitation linear prediction (MELP) low-speed compression coding on the digital voice so as to obtain voice data, grouping and performing Turbo coding on a voice data bit stream so as to obtain different groups of data, performing orthogonal frequency division multiplexing (OFDM) multicarrier modulation on every group of data and converting a modulated signal into a sound wave through an underwater acoustic transducer for transmitting in a sea underwater sound channel; and at a communication receiving end, performing underwater sound OFDM multicarrier modulation on a received signal after synchronization so as to obtain demodulation data, performing Turbo decoding on the demodulation data, performing MELP decoding on the data so as to synthesize the digital voice, converting the digital voice into simulated voice by using a digital to analogue (D / A) converter and outputting the simulated voice through a loudspeaker.

Description

technical field [0001] The present invention relates to a communication method, in particular to an improved low-rate speech coding algorithm using Mixed Excitation Linear Prediction (MELP for short), underwater acoustic Orthogonal Frequency Division Multiplexing (OFDM for short). ) Underwater digital voice communication method combining multi-carrier modulation and Turbo coding. Background technique [0002] Underwater voice communication has important application prospects in many aspects such as marine scientific research, marine resource exploration, frogman communication and diving entertainment. However, due to the rapid attenuation speed of radio waves and light waves in seawater media, sound waves must be used to achieve long-distance underwater communication. Early underwater voice communication equipment generally used analog SSB modulation technology, such as the AN / WQC-2A SSB voice communicator used by the US Navy. This analog modulation communication method is...

AI Technical Summary

Problems solved by technology

This method has the advantages of long communication distance, low communication rate requirements, and strong channel adaptability. However, its communication quality depends largely on the ability of speech recognition software to recognize different voices. At the same time, the synthesized voice is a standard voice, which cannot be distinguished. The speaker, this defect makes it very limited in the application of actual underwater voice communication; the latter sender first performs low-rate parameter compression coding on the input voice, and then uses the multi-ary phase shift key with a higher communication rate The empty (Multi-Phase ShiftKeying, referred to as MPSK) modulation method sends the coded data to the communication receiver, and the receiving end performs coherent demodulation on the received signal, and finally synthesizes and outputs the voice

The voice output by this method has the advantages of high intelligibility, naturalness and clarity. However, because underwater acoustic channels generally have relatively large multipath delays, the communication receivers usually need to use complex adaptive time delays. Domain channel equalization and error correction coding algorithm to achieve more reliable communication

Images