速度识别能力的高低直接决定了激光探测系统性能的优劣，受探测器带宽限制，传统激光探测系统无法实现对数马赫目标的速度多普勒信号检测。提出的同偏振双频激光相干探测测速方案成功解决了该难题，极大提高了系统效能。基于双频激光相干探测原理，分析了在实际应用中的振幅扰动、相位扰动及频率扰动等时频扰动对该系统信噪比的影响并与单频系统进行了对比。结果表明：单、双频系统回波信号信噪比受振幅扰动的影响基本一致；而针对各种频率扰动和相位扰动，双频激光探测系统回波信号信噪比明显高于单频激光探测系统，如当相位扰动达0.5π时，单频激光探测系统信噪比接近0 dB，而双频激光探测系统信噪比仍高于18 dB。

The performance of laser detection system (LDS) is directly influenced by the velocity identification capability. Due to the bandwidth restriction of the receiver, the laser Doppler shift of the high speed targets can not be detected in LDS. A dual-frequency laser coherent detection (DLCD) system is introduced consequently, which has successfully solved the problem and enhanced the system capabilities obviously. Based on the theory of the DLCD, the signal-noise ratio (SNR) influenced by the amplitude disturbance, the phase disturbance and the frequency disturbance are analyzed, and the characteristics different from the signal-frequency laser coherent detection (SLCD) are illuminated. The simulation results indicate that the amplitude disturbance effect on the SNR of DLCD is consistent with that of the SLCD. For various kinds of frequency and phase disturbance, the SNR of DLCD is higher than that of the SLCD. When the phase disturbance increases to 0.5π, the SNR of SLCD is 0 dB, while the DLCD is still higher than 18 dB.