Underwater Voice Communication System Based On OFDM-MFSK Technology And Its Implementation

With the deepening of human exploitation of marine resources,the demand for information and data transmission through underwater acoustic channels has greatly increased.Due to the inherent characteristics of underwater acoustic channels,underwater voice communication technology has been widely applied in military and civilian fields such as ocean scientific research,frog man diving,and submarine ship training.Therefore,starting from improving system performance and reducing system complexity,this article conducts research on an underwater voice communication system based on OFDM-MFSK technology.By designing a digital communication algorithm based on OFDM-MFSK technology,underwater long-distance digital voice communication can be achieved,enabling clear voice information exchange between underwater frogmen and surface deck units or other frogmen.Targeting the application requirements of high-performance long-distance digital voice communication MODEM.This article conducts design,implementation,and verification research on the hardware circuit and software algorithm of the underwater acoustic digital speech communication system.Firstly,according to the requirements of technical indicators,research and design related to the hardware of the underwater voice communication system were carried out.The hardware circuit of the system was designed based on the system’s working indicators and relevant parameters.Suitable digital processing chips and voice compression chips were selected,and the device selection and circuit diagram principle design of the receiving and transmitting hardware circuits were completed.Secondly,in terms of software algorithms,OFDM-MFSK communication technology is adopted,and processing processes such as channel encoding and decoding,symbol mapping,Doppler estimation and compensation are added.Based on this,communication performance simulations of the baseband and passband of OFDM signals are carried out;Due to the fact that OFDM-MFSK communication does not require channel estimation and equalization,the robustness of the system communication is improved and the complexity of the modulation algorithm is reduced;Completed the program design of the system’s receiving and transmitting parts,and also determined the frame structure of the OFDM transmission signal,completing the implementation process of voice signal transmission and reception.Then,a fixed-point DSP implementation of underwater voice communication algorithm was carried out on the hardware platform centered on TI company’s TMS320C6416 T,mainly including the reception and transmission of OFDM signals,as well as signal related modulation and demodulation,channel encoding and decoding,etc.At the end of this underwater voice communication MODEM design,key design parameters and waveform verification tests were conducted on the hardware circuits of each part of the system.The communication performance of the underwater voice communication system was verified through pool and field tests.The experiment shows that the software algorithm implemented in this design can work stably and reliably on the hardware circuit,and all software and hardware technical indicators meet the design requirements of the system.The designed communication MODEM can achieve long-distance digital speech signal transmission underwater,with good speech signal intelligibility and broad application prospects.