基于ADV212的探空火箭图像采集与压缩系统

针对探空火箭遥测带宽低、图像监控通路多、系统小型化等设计难点，本文提出了一种基于ADV212的图像采集与压缩系统设计方案。采用可以同时支持无损和高压缩比有损压缩的JPEG2000图像压缩标准，提出适用于箭上图像采集特点的通道切换和中断处理策略，并以“乒乓”操作的流水线作业方式实现多路图像通道数据吞吐，通过两个实时发送通道和一个缓存发送通道向火箭遥测链路发送图像数据。提出了一种具有动态帧频和压缩比的图像压缩方案，解决了探空火箭遥测带宽有限这一问题。本设计以Virtex-4系列FPGA作为系统控制核心，采用ADV7182和ADV212分别完成图像的采集和压缩，分别采用SRAM和SDRAM实现图像的实时传输和缓存传输。通过比较图像间的PSNR值，试验并分析了适用于CCD图像的压缩滤波器和小波变换级数，得到了较为满意的图像质量。设计较好地满足了本次空间环境垂直探测探空火箭的图像采集任务。

Image capture and compression system based on ADV212 for sounding rocket

To design image system for sounding rockets faces many difficulties such as the limited telemetry bandwidth, multiple camera channels and a limited size, therefore an appropriate image capture and compression system based on ADV212 has been proposed. The images are compressed as JPEG2000 standard which supports both lossless and high ratio compression, so acceptable quality images can be transmitted through the limited-bandwidth telemetry channel. An effective channel switch and interrupt processing method which is suitable for on-board design has also been proposed. The image data is transmitted by assembly line based on ping-pong operation and sent to the telemetry module on sounding rocket via two real-time channels and one buffering channel. The images compression scheme, which supports both dynamic frame frequency and dynamic compression ratio, is proposed to deal with the limited telemetry bandwidth. The whole system is controlled by a Virtex-4 FPGA, and images are decoded by ADV7182 and compressed by ADV212. The real-time data transfer is approached by SRAM, while the buffering data transfer is approached by SDRAM. The suitable choices of compression filter and wavelet transformation level for CCD images are analyzed through experiments by comparing PSNR between images. This image compression system fully satisfies the image monitor mission of space environment vertical exploration sounding rocket.