8mm脉冲磁控管测云雷达测速多普勒化

Dopplerizing an 8 mm Pulsed Magnetron Cloud Radar

8mm磁控管发射样本中频信号的起始相位随机分布，脉间频率抖动范围为±2MHz，脉内频率变化为500kHz。为了克服这些问题，提出了一种适合于国内第一套毫米波脉冲磁控管测云雷达的测速多普勒化算法，幅度信息从回波数字下变频经低通滤波器后直接提取，相位信息由零中频回波IQ信号与发射样本IQ信号进行复卷积提取，并算法仿真结果表明多普勒频率误差不超过4Hz。基于FPGA技术实现了测速多普勒化算法，利用高速缓存的设计思想实现了复卷器的优化，利用CORDIC算法实现了幅度与相位的高精度提取，并完成了算法在实际雷达系统中的测试，雷达的脉冲重复频率为1000Hz，多普勒频率在-496～500Hz范围内，雷达终端显示的速度值与理论值一致；回波信号幅度值为-76～6dBm，得到的速度值与理论值一致。经过该算法处理的地物杂波回波的多普勒速度在零值附近分布，云体目标的回波速度图清晰可见。该算法已经成功应用于8mm脉冲磁控管测云雷达系统。

Transmitter sample IF（ Intermediate Frequency） signal of 8mm pulsed magnetron has a random starting phase. Its frequency chirps at ± 2 MHz during pulse, and 500 kHz in pulse. To overcome these problems, a novel modified coherent-on-receiving processing algorithm is presented for the first set of domestic pulsed magnetron MMW（ Millimeter Wave） cloud radar. The amplitude information is extracted directly after a low-pass filter（LPF）. The phase information extraction is from convolution processing between zero IF echo IQ signal and transmitter IQ sample signal. The algorithm simulation results show that Doppler frequency error is less than 4 Hz. The algorithm is implemented based on FPGA. The complexity convolution processor is optimized by designing high speed caches. High precision amplitude and phase extraction processing are realized with Coordinate Rotation Digital Computer （CORDIC） algorithm. The test of the algorithm in actual radar system is also completed. When radar pulse repetition frequency（RPF） is 1 000 Hz, Doppler frequency in - 496～ 500 Hz, radar terminal velocity value is correct in theory. Echo signal amplitude values in - 76～6 dBm, the calculated velocity value conforms to the theoretical one. Processing ground clutters by this algorithm show that the velocity of the return signal is disturbed near zero, the echo velocity pictures of cloud targets are available. The modified coherent-on-receiving processing unit has been used in 8 mm pulsed magnetron cloud radar system.