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本文分析了LiTaO_3器件在高频宽带红外通信接收系统中的噪声模型,并进行了相应的计算。在使用条件下系统的噪声以前放输入级FET的电源噪声及输入电阻R_g的热噪声为主。并与实测数据作了比较,实测与理论计算符合较好。为改善热释电探测器的高频衰落,系统采用话音信号的高频提升及接收机前放的频率补偿技术,前者对改善高端信噪比有利。文中还提出增大前放级FET的工作电流,适当选择较小输入电容的场效应管,以达到全面考虑系统的信噪比和频响特性。为改善信号受大气湍流调制的低频起伏,降低了放大器输入电阻R_g(5×10~7Ω→10~8Ω),极大地降低了探测器的低频灵敏度,获得了较好的效果。根据大气通信距离方程考虑大气湍流强度的起伏效应,在2km距离计算了探测器光敏
This paper analyzes the noise model of LiTaO_3 device in the high-frequency broadband infrared communication receiving system and carries out the corresponding calculation. The noise of the system under the condition of using previously puts the power noise of the input stage FET and the thermal noise of the input resistance R_g mainly. Compared with the measured data, the measured and theoretical calculations are in good agreement. In order to improve the high-frequency fading of the pyroelectric detector, the system adopts the high frequency of voice signal and the frequency compensation technology of the receiver. The former is good for improving high-end signal-noise ratio. The paper also proposed to increase the operating current before the release of the FET, the appropriate choice of smaller input capacitor FET in order to achieve full consideration of the system’s signal to noise ratio and frequency response characteristics. In order to improve low frequency fluctuation of the signal modulated by atmospheric turbulence, the input resistance R_g (5 × 10 ~ 7Ω → 10 ~ 8Ω) of the amplifier is reduced, which greatly reduces the detector ’s low frequency sensitivity and achieves good results. According to the atmospheric communication distance equation considering the fluctuation of the atmospheric turbulence intensity, the detector photosensitivity was calculated at a distance of 2 km