Algorithm and Implementation of Motion Compensation in PD Radar Based on DDS

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.