直接数字合成技术（DDS）可以灵活地产生点频、线性调频、频移键控等多种信号，越来越多的DDS芯片被应用于射频系统设计中。为了获得更高的距离分辨率，机载合成孔径雷达（SAR）需要更大的信号带宽。受限于DDS芯片的调频转换速率，在大带宽下，DDS产生的线性调频信号相比理论信号可能存在频率失真。讨论了主流DDS芯片的选择和信号产生方案的设计。利用MATLAB软件仿真了调频转换速率对脉冲压缩的影响，并在实际系统中验证了仿真结果。该方法可以评估在给定硬件条件下信号产生方案的可行性，对信号产生的频率和器件选择有一定的

As DDS can generate conveniently single-tone, chirp, FSK, etc. DDS chips are used in more and more RF systems. In order to obtain higher range resolution, the airborne SAR needs larger signal bandwidth. Compared to the theory signal, the chirp produced by DDS under large bandwidth, may have frequency distortion due to the limited chirp-rate. Discuss the selection of leading chips and the design for signal generation. Apply the MATLAB software to simulate the influence of chirp-rate in the pulse compression, and validate the simulated results in a real system. The method can evaluate the feasibility of a design for signal generation under a given hardware, also give some suggestions to frequency or chip selection for design.

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