Design Of Remote Control Multi-point Underwater Acoustic Transmission System

In recent years,with the goal of building a Marine power,the country has increased the research investment in underwater acoustic technology and put forward higher requirements for underwater sound sources.Acoustic wave is the only known form of energy suitable for longdistance propagation in sea water,so underwater sound source is widely used in underwater target detection,underwater acoustic countermeasures and other fields.Based on this background,a remote-controlled multi-point underwater acoustic transmission system is developed in this paper.The system is divided into four subsystems:remote control subsystem,low frequency sound source subsystem,beacon subsystem and signal control subsystem.The remote control sub-system is divided into control unit and control unit.The control unit is installed on the mother ship,while the control unit and the other three sub-systems are installed on the unmanned boat.When the height of the radio antenna frame on the mother ship and the unmanned boat is more than 3.5 meters,the remote control subsystem on the mother ship can stably realize the control of the subsystem carried by the unmanned boat within a radius of 10 kilometers with itself as the center.After the control unit of the remote control system issues the command,the low frequency sound source subsystem and the control unit of the remote control subsystem respond respectively.The low frequency acoustic source system directly analyzes the parameters of the transmitted signal and transmits the specific underwater acoustic signal.Signal types include continuous single frequency signal,CW pulse,LFM pulse and file waveform stored in SD card.In order to realize underwater acoustic countermeasures,the delay time can be set by command to control multiple low frequency acoustic source subsystems to simultaneously transmit underwater acoustic signals.After receiving the instruction,the control unit of the remote control subsystem forwards it to the signal control subsystem.Signal control subsystem controls the mechanical structure of the beacon into the water subsystem.The beacon sub-system is equipped with a high-precision cesium atomic clock synchronization module,which can complete the synchronous timing and high-precision punctuality functions with the GPS receiver.Meanwhile,it is equipped with a high-precision pressure sounding module,which can receive pressure parameters in real time.After the beacon subsystem enters the water,it reads the instruction information pre-stored by F-RAM,and analyzes the type of transmitting signal,signal parameters,precise time of transmitting signal and water depth pressure of transmitting signal.After reaching the set threshold,multiple beacon subsystems simultaneously transmit underwater acoustic signals at a specific time or depth.Finally,the whole system is tested.The remote control subsystem successfully realizes the remote control distance of more than 10 km,and verifies that the limitation of remote control distance can be solved by using short message communication of Beidou shipborne terminal.The low-frequency sound source sub-system can accurately receive the command information sent by the remote control sub-system,and accurately transmit underwater acoustic signals and file waveforms stored in the SD card.The beacon sub-system can read the data of cesium atomic clock synchronization module and sounding pressure module in real time.When the set time or depth pressure is reached,the underwater acoustic signal can be accurately emitted.After impedance matching of the power amplifier circuit board,the conversion efficiency can reach90%.In the pool experiment,the low-frequency sound source sub-system and beacon subsystem are connected to the power amplifier and the underwater acoustic emission transducer for joint test.The beacon sub-system meets the technical index of sound source level greater than 180 d B,and the systems can work for a long time,stably and reliably.