| The flight recorder sank into the sea after the plane crashed into the sea.The acoustic beacon on the flight recorder starts working once beacon immerses in water.The acoustic beacon' sound source level is low,operating frequency is high,acoustic energy decays quickly,working life is short.These disadvantages make it difficult to find the beacon in the sea.Due to high signal frequency and large amount of data,complex signal processing algorithm is difficult to be applied to sonar system.In this paper,aiming at this problem,a real-time underwater sonar positioning system with high operating performance and stability is designed.Moreover,the system has the characteristics of small size and light weight.It can be carried by an underwater unmanned vehicle and dive down to 2?6km for accurate positioning.The software and hardware design of the system platform is completed.The system platform is divided into three parts: analog receiver,signal acquisition system and signal processing module.First,according to the functional requirements of the system platform,the overall design of the signal processing platform is proposed.The analog receiver part adds a gain control function,and the single-chip microcomputer is used in conjunction with the digital potentiometer to achieve arbitrary change of the receiver amplification within the controllable range.For the real-time and stability requirements of the system platform,the digital part of the platform is built with a rugged and reliable Compact RIO controller and a powerful DSP C6678 for signal processing.As the signal acquisition system of the platform,the Compact RIO controller performs signal acquisition,real-time preprocessing,data storage,data network transmission,and serial data receiving functions independently.The data preprocessing performs beamforming algorithm and signal downsampling.The signal processing module consists of two C6678 s,which respectively process the data of two hydrophone arrays.C6678's powerful signal processing capability can complete the real-time operation of a large amount of data.The data transmission of the two DSPs is implemented by high-speed interface SRIO.Its high bandwidth characteristics greatly reduce the transmission delay and lay a solid foundation for the parallel processing of the two DSPs.In this paper,the gain control circuit design,signal acquisition circuit design and SRIO interface interconnect backplane design are completed,and the gain control,signal acquisition,data preprocessing,data storage,network transmission and SRIO interface data transmission functions are realized.After the completion of the software and hardware design,the hardware circuit and partial function is debugged in the laboratory.Finally,the overall feasibility,real-time performance and stability of the system platform are verified experiments in ponds and lakes. |
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