| The Voyage Data Recorder(VDR)is a device designed to record various data in a ship's navigation.After an accident occurs in the ship,the cause analysis can be performed based on the objectively recorded data in the VDR.Among them,the navigation radar image is one of the most important data,because it records the most detailed picture of the surrounding sea environment during the ship's navigation.Since radar image data is very large and requires real-time transmission backup,it is necessary to compress the radar image.This paper studies and implements the radar image recording and compression system.According to the requirements of IEC61996 and China Classification Society,this paper firstly designs the system.The design requirements for radar image acquisition based on HDMI digital interface and compression of radar image using high performance JPEG2000 lossless compression standard are determined.From the function division,the whole system is divided into three parts:acquisition,compression and transmission.In terms of function implementation,this paper adopts the means of software and hardware collaborative design and implementation,making full use of hardware and software resources and features,so that the system can efficiently run.Aiming at the problem of JPEG2000 compression algorithm with high computational complexity,this paper proposes a heterogeneous multi-core based JPEG2000 lossless compression implementation.After studying the JPEG2000 compression algorithm,this paper makes a reasonable division of software and hardware task assignment.The image preprocessing and wavelet transform functions are implemented in Programmable Logic(PL).The embedded Linux system is built in the Processing System(PS)and OpenMP is ported.Based on OpenMP,a parallel algorithm model is built for the EBCOT encoder in JPEG2000,and a pipeline design is added between the PL processing and the PS encoding,which achieves twice the compression speed and reduces the system power consumption.Because the system is implemented by software and hardware collaborative design,there is a large amount of data interaction between PL and PS.Based on AXI bus,this paper designs high-speed and low-speed communication methods for transmitting data and control information,and The driver is designed based on the Platform bus in the embedded Linux system to ensure the data interaction between the modules.In the aspect of radar image acquisition,the decoding and transmission of the HDMI protocol radar video source is realized by using PL,and radar image acquisition with a resolution of up to 1280x1024 can be realized.The data backup sends the compressed image to the data storage terminal for backup via Ethernet.The overall system was developed on the Vivado development platform and implemented on the Zynq7000 series Miz-701N development board.Finally,a test platform was set up to test the functions and performance of each module and the whole system.The test results show that the system can operate normally and stably,and the technical indicators meet the design requirements. |
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