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在激光外差探测中,为了增强在频谱密度上对多普勒频移峰值的识别能力,提升对目标的探测概率,提出一种采用伪随机序列对连续激光进行调制的外差探测方法。应用伪随机序列的M序列码对发射激光和本振光同时进行频率调制,接收信号光和经时间延迟后的本振光相干叠加形成拍频信号。其特点是二进制码调制同时作用于发射信号光和本振光,使外差信号频谱上同时出现3个峰值,减小了外差探测时的虚警率,提高了探测的信噪比。通过模拟仿真计算,证明了此探测模型有着良好的抗干扰能力和较好的噪声滤除能力。
In laser heterodyne detection, in order to enhance the recognition ability of Doppler shift peak in spectral density and improve the detection probability of target, a heterodyne detection method using pseudo-random sequence to modulate continuous laser is proposed. The M-sequence code of the pseudo-random sequence is used to perform frequency modulation on the transmitting laser and the local light simultaneously, and the received signal light and the local light after the time delay are coherently added to form a beat signal. Its characteristic is the binary code modulation at the same time on the transmitted signal light and local light, so that heterodyne signal spectrum at the same time there are three peaks, reducing the heterodyne detection of false alarm rate, improve the detection of signal to noise ratio. Through simulation calculation, it is proved that the detection model has good anti-interference ability and better noise filtering ability.