针对线性调频(LFM)体制雷达中目标的运动会造成一维距离像的时移问题,提出了利用LFM 信号的时延-多普勒耦合特性,在中频混频时额外增加多普勒耦合项,用现场可编程门阵列的直接数字式频率合成器(DDS)核实现运动补偿的方法。首先,对运动目标的线性调频回波信号建立了模型;然后,基于该回波模型推导了运动补偿时需增加的多普勒耦合项,DDS 的控制字公式;最后,针对该理论进行了仿真和实验。仿真和实验结果表明:采用该方法进行运动补偿后的积累峰值分别提高了3. 66 dB 和2. 68 dB,旁瓣抑制比分别提高了7 dB 和5. 92 dB,因而该方法有效且可用。

The problem that the movement of the target in linear frequency modulation(LFM) radar system should cause one-dimensional image time-lapse, the method that exploiting the signal delay of LFM Doppler coupling characteristics to mix the Doppler frequency additionally in intermediate frequency mixing and using the direct digital synthesizer (DDS) of field programmable gate array to achieve motion compensation are proposed. Firstly, the model of chirp echo from a moving target is presented. Then, the additional Doppler coupling term, control word formula of DDS is derived based on this model. Finally, some simulation and experiments are carried out for this theory. Simulation and experimental results indicate that the accumulation peak value after motion compensation with this method increased by 3. 66 dB and 2. 68 dB respectively. The side lobe suppression ratio increased by 7 dB and 5. 92 dB respectively. Experimental results prove the effectiveness and availability of the method.

TN958.2