摘要
MSM激光距离成像雷达将微波雷达中调频测距原理应用到激光雷达,采用一个线性调频的射频副载波调制激光输出强度。本文提出了雷达中调频信号发生器产生宽带线性调频信号的设计思路,并着重阐述DDS+PLL实现宽带线性调频的过程。首先建立四阶二型锁相环架构,分析其对DDS产生的线性扫频信号实现频率稳态跟踪的可能性,然后进行锁相环锁频的初步仿真并得到环路基本参数,最后在输入DDS产生的线性扫频信号前提下仿真环路的频率跟踪性能。仿真结果表明四阶二型锁相环实现了对DDS产生的线性扫频信号的频率跟踪及频带扩展,满足了雷达距离精度对线性调频信号的宽频带要求。
MSM laser radar（ladar） adopts the same frequency modulation（FM） ranging principle as the microwave radar does.The ladar′s laser power is amplitude modulated with a radio-frequency subcarrier which itself is linearly frequency modulated.In this paper,the scheme of wideband linearly FM signal generator is presented,and the detail of realizing linearly FM signal with a direct digital frequency synthesis（DDS） and phase-locked loop（PLL） is illustrated specifically.The architecture of type-Ⅱ fourth-order phase-locked loop is established and its possibility of steadily tracking linear frequency sweeping signal which is produced by DDS is also analyzed and simulated.Simulation results show that the type-Ⅱ fourth-order PLL can achieve frequency bandwidth expansion of linearly FM signal and meet the requirement of linear FM broadband signal.That′s the foundation to guarantee the range precision of MSM ladar.
出处
《激光与红外》
CAS
CSCD
北大核心
2010年第9期945-949,共5页
Laser & Infrared
