Intermediate Frequency Data Collection And Storage System Based On Embedded Platform

As a digital navigation system,AIS(Maritime Automatic Identification System)is used for ship collision avoidance and recognition,and it has played a great role in improving the safety of maritime traffic.The location information of AIS system is provided by the GNSS(the Global Navigation Satelite System).In order to improve the reliability of the AIS system,a land-based positioning system is now under study in the maritime field as the backup system of GNSS.The Navigational Research Institute of Dalian Maritime University has developed a ship autonomous positioning system based on AIS shore station.In order to analyze and deal with real-time signal information of AIS and GNSS in the process of systematic research,intermediate frequency data of AIS and GNSS needs to be collected and stored,which is conducive to analyzing the signal propagation characteristics and providing raw data for equipment performance testing,having very important practical value and research significance.This paper designs an IF data acquisition and storage system based on embedded triple-core platform,which can realize the acquisition and storage of IF data.The hardware platform includes the acquisition module,Xilinx Spartan-6+OMAPL13 8 triple-core platform and storage device SATA.The ADS830E collector which implement the acquisition of AIS signals send data to the three-core FPGA I/O port through the interface adapter module.The NJ1006A RF receive signals from the GPS antenna and connect with level conversion module,which powerd by the power supply module.Then connect the output of the level conversion module to the FPGA I/O port of the triple-core platform,and finally save the data to the SATA hard disk.The software of the system is divided into acquisition,transmission,storage three parts.Collection part of the program used to control the collector timing and data reception,written by Verilog language,running in the FPGA.The program of the transmission part includes the DMA receiving uPP data of the DSP and the access of the dual-core data in the shared memory.The DSP runs the SYS/BIOS real-time operating system,the ARM runs the Linux operating system,and uses TI's SYSLINK dual-core communication component to implement the data interaction.The final data is stored as a single file per 2M bytes into the SATA.After the completion of data storage,testing and verification of the system are necessary.The AIS intermediate frequency digital data is drawed in the Matlab,and the FFT is performed to compare waveform and the center frequency in the oscilloscope to verify the accuracy.Then check the GPS waveform' consistency with the program' logic through CHIPSCOPE to verify its accuracy.