【摘要】 太阳射电观测系统提出信号频段跨度大、观测频点多且频率及频点带宽可变、高精度多通道信号时间同步等要求。在此研究并采用奈奎斯特中频采样、多通道并行数字正交解调、滤波抽取得到数字基带信号。给出适合高倍率抽取的级联高效滤波器结构和易于工程使用的CIC滤波器幅度补偿方法。采用可编程延迟器实现系统高精度时间同步要求。完成了基于FPGA的硬件编程与硬件资源评估,使用线性调频信号作为测试信号在评估板上进行实际测试。结果表明在不同工作模式下,400 MHz带宽信号在脉冲重复时间内可被滤波抽取输出16路带宽可变的窄带正交基带信号,通带幅度平坦度、相位正交度等指标符合系统要求。最后讨论了硬件资源使用情况和潜在的性能升级空间。更多还原

【Abstract】 Solar radio heliograph observation system is a multi-bandwidth,multi-mode and high precise multi-channel synchronization system. Nyquist IF sampling,multi- channel parallel digital quadrature demodulation,multi- rate decimating are used to acquire the base- band digital signal in this paper. A modified frequency response compensation approach suitable for CIC filter is presented. A programmable delay device is used to realize high precise multi-channel signal synchronization. VHDL programming and hardware resource assessment based on FGPA were achieved. The actual test on a evaluation board shows that the intermediate frequency signal with the bandwidth of 400 MHz can be filtered and decimated to 16-channel narrow quadrature baseband signal which bandwidth can be changed according to the system operation mode. The amplitude flatness and phase orthogonality of the output signal can satisfy the requirements of the system. At last,the consumption of the hardware resource and capacity of potential upgrade are discussed.更多还原