低杂散复杂线性调频的实现

Approach to the lower spurs and complex LFM based on FPGA and NCO

针对采用脉冲压缩体制高性能超视距雷达的应用场合,提出了一种应用现场可编程逻辑阵列(FP-GA)和数控振荡器(NCO)相结合实现低杂散复杂线性调频(LFM)方法。该方法利用FPGA编程灵活和提高D/A量化位数,降低量化离散杂散的特点,在分析现有直接数字合成的不足以及量化离散杂散与D/A量化位数关系的基础上,通过FPGA内形成数据接口、时序分配和双重叠加相位累加器的方式控制(NCO),实现低杂散的复杂线性调频。给出了实现的原理图、FPGA内部逻辑图和试验结果,通过硬件验证了该方法的有效性。

A method is presented for using field programmable gate array （FPGA） and numerical control oscillator （NCO） to approach a lower spurs and complex linear frequency modulation （LFM）. It described the relationship between direct digital synthesize （DDS） spurs and D/A converter digits which is based on noise floor and spurs analyzing, and achieved a lower spurs and complex LFM via a date interface, timer sequence distribution and two phase accumulations in FPGA. It improved the quality and adaptability for baseband signal in radar and communication system.