Underwater Acoustic Communication Device Based On Multi-Channel Receiving And Transmitting

In recent years,due to the increasingly serious environmental damage and rapid consumption of resources,people gradually focus on the ocean.As countries around the world carry out various activities on the seabed,such as resource exploration,military activities,and biological surveys,this has led to further development of underwater acoustic communication technology.However,the bandwidth of underwater acoustic communication is narrow,which limits the channel capacity and communication rate.Compared with land-based communication,the underwater acoustic communication environment is also more complicated and harsh,and is vulnerable to factors such as temperature,tides,and salinity.The multi-channel receiving and transmitting technology can increase the channel capacity and communication rate under the condition of the same bandwidth,and reduce the bit error rate.Therefore,the underwater acoustic communication device based on multi-channel receiving and transmitting has been become a research focus.At the same time,because the communication device is used to work underwater for a long time,its standby power consumption should be as low as possible.In response to these situations,and referring to the relevant theories and circuits,a multichannel and low-power underwater acoustic communication device is designed in this thesis,which meets the requirements of small size and long-distance communication at the same time.In this thesis,the scheme analysis and circuit design of digital processing circuit,dual channel transmitter and eight channel receiver are carried out,and the feasibility of the hardware of the communication machine is verified by experiments.The main work of this thesis is as follows:1.This chapter is used to introduce the hardware system framework of the hydroacoustic communication machine and explain its basic principles.Aiming at the requirement of multichannel data processing capability,a digital processing circuit of FPGA+ARM+DSP is designed.At the same time,in response to the requirement of low power consumption,a twolevel watch circuit is proposed.The watch circuit has a two-level detection circuit.The secondlevel detection circuit is used to detect the amplitude of the wake-up signal,when the received signal is greater than the receiving threshold,then low-power processor MSP430 is awakened.Subsequently,the first-level detection circuit is activated by the processor,the wake-up signal is collected and analyzed,and then the communication machine is awakened.In this circuit scheme,the standby power consumption of underwater acoustic communication machine is as low as 18 m W,which greatly improves the standby time of communication machine.2.This chapter is used to introduce the signal chain of the transmitting circuit and the specific circuit implementation in detail,and the dual-channel transmitter is designed.At the same time,the transmitter circuit is separated from other circuits in the system,and the dualchannel transmitter is made into a modular circuit to facilitate the expansion of the transmission channel.In addition,to improve the efficiency of the traditional class D power amplifier circuit,a new class D power amplifier circuit is adopted.Then,impedance matching is used to match the underwater acoustic transducer to further improve the efficiency of the transmitter.3.This chapter is used to analyze the receiving circuit of the communication machine,the signal chain of the receiving circuit is introduced in detail,and the eight-channel receiver is designed.At the same time,the receiver circuit is separated from other circuits in the system,and the eight-channel receiver is made into a modular circuit to facilitate the expansion of receiver channels.In addition,in view of the problem that the gain of different channels of the receiver is not independent and discontinuous,four AD605 dual-channel analog gain chips are used to design the automatic gain amplifier circuit.The gain of the receiving channel is independent and continuous by using this scheme,and has a dynamic gain range of up to 48 d B.4.Physical production and experimental verification.The physical production is made according to the circuit diagram,and then the whole machine was jointly debugged.In order to verify the performance of the circuit,the relevant indicators of the transmitter and receiver are tested.Finally,the underwater acoustic communication machine is tested in the pool and Wanlv lake,which further verified the feasibility of the communicator and the communication distance of up to 8 kilometers.