一种大测距动态范围高重频相干测距测速激光雷达(Ⅱ):信号调制  

A coherent range and range-rate detection Ladar with large ranging dynamic range and high-repetition-rate(Ⅱ) : Signal Modulation

作　　者：吴军[1,2] 洪光烈[1,2] 张鸿翼 李飞[1,2] 徐卫明 何志平[1,2] 舒嵘 

机构地区：[1]中国科学院上海技术物理研究所空间主动光电技术中科院重点实验室,上海200083 [2]量子信息与量子科技前沿协同创新中心,安徽合肥230026

出　　处：《红外与毫米波学报》2015年第3期321-332,共12页Journal of Infrared and Millimeter Waves

基　　金：国家自然科学基金863计划(2014AA7100012)~~

摘　　要：针对"双频双调制双本振(DFDMDL)"大测距动态范围高重频相干测距测速体制,分析了该体制信号调制需要考虑的调频线性度、发射光和本振光信号的"幅-频"特性、对称三角线性调频(STLFM)信号的周期稳定性等因素,通过参数的对比、仿真及实测,提出了适合本系统的信号调制方案.实测结果表明,采用声光移频器(AOFS)外调制提供高线性度STLFM信号,直接数字频率合成(DDS)驱动AOFS,通过DAC调节射频驱动源功率补偿AOFS非平坦的"幅-频"特性,以及基于FPGA的高精度时间测量系统监测STLFM信号周期及测量多个STLFM周期间的时间差,可以使该"双频双调制双本振"体制具有较高的距离测量精度,并为通过脉冲积累减小发射能量的途径提供了可能.For the 'dual-band dual-modulation dual LO( DFDM DL) 'range and range-rate detection ladar with large ranging dynamic range and high-repetition-rate,we analyzed the LFM modulator linearity of the signal,the'amplitudefrequency 'characteristic of the local and emitted light signal,the period stability of the symmetrical triangular linear frequency modulation( STLFM) signal,which are needed to be considered in the ladar design. The signal modulation scheme for the system was proposed by comparison,simulation and measurement of different parameters. In the desgin,we used the acousto-optic frequency shifter( AOFS) to provide external modulation for high linearity STLFM signal,and the direct digital frequency synthesis device( DDS) to drive AOFS. We also proposed and used the DAC to adjust the RF drive source power to compensate the non-flat'amplitude-frequency'characteristics of the AOFS,the High Precison FPGA based TDC measures the STLFM period and the time between multiple STLFM signals. The result demonstrated that the DFDM DL system has a high accuracy of ranging and has the potential ability of pulse integration by using this scheme.

关 键 词：相干激光雷达 双频双调制双本振 对称三角线性调频 声光移频器 DDS 高精度时间测量 

分 类 号：TN957.51[电子电信—信号与信息处理]