星载SAR中频数字接收机的FPGA设计与实现

在现场可编程门阵列(field programmable gate array, FPGA)中设计与实现了一种星载合成孔径雷达(synthetic aperture radar, SAR)中频数字接收机，并对数据形成技术进行了研究。考虑到FPGA乘法器资源有限，在详细分析了中频、采样率和抽取因子三者关系的基础上，实现了不同带宽信号的多相下变频优化结构。为减轻数据下传链路的压力，实现了压缩比可变的分块自适应量化(block adaptive quantization, BAQ)压缩模块。最后给出了设计实例，实验结果证明了方案的有效性：BAQ 8:3输出结果I、Q两路信噪比为14.6 dB，脉压后主瓣展宽只有2‰，积分旁瓣比达到了理论值的93%。

Design and implementation of space borne SAR IF digital receiver on FPGA

The design and implementation of a space borne synthetic aperture radar (SAR) inter frequency (IF) digital receiver including data formation on field programmable gate arrays (FPGA) is proposed. An improved polyphase frequency down converting structure of different bandwidth signals is implemented, considering the limited multipliers in FPGA and after carefully analyzing the relationships among IF, sampling frequency and decimation factor. To alleviate data downlink pressure, a block adaptive quantization (BAQ) module with a flexible compression ratio is developed. Finally the design instance is given and the properties are verified by experimental results. 2‰ mainlobe expansion and a 93% integral sidelobe ratio of theoretical value after matching filter are achieved with 8:3 BAQ compression ratio, 14.6 dB I/Q channel signal to noise ratio (SNR).