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本文描述了采用LiTaO_3直接探测及电源调制的10.6μm通信系统,对系统的最小可探测功率及信噪比进行了分析和计算。提出了NEP及S/N的简便计算公式。并指出系统的NEP与工作频率的依赖关系。列出的典型测试数据表明,理论计算与实验数据基本符合。本文还分析了大气湍流对通信的影响,在本系统中主要表现为低频(100Hz以下)光强随机起伏。提出系统后续电路加AGC,并降低热释电探测器的低频灵敏度,基本上可克服大气湍流效应。文中特别强调采用10.6μm波段具有良好的穿雾霾能力,在洁净大气条件下可与可见、近红外相媲美,而在恶劣的气象条件下却优于上述波段。由于采用热释电探测器,致使系统不需要苛刻的致冷技术,操作、维修尤为方便。用于沿海岛屿、江河两岸、边防哨所定点通信,具有特殊的实用价值。该系统在2km、5km试用实验中,已接入市话网,话音清晰、工作可靠。
This paper describes a 10.6μm communication system that uses LiTaO_3 direct detection and power modulation to analyze and calculate the minimum detectable power and SNR of the system. Proposed simple calculation formula of NEP and S / N. And points out the dependence of system NEP and working frequency. The typical test data listed shows that the theoretical calculations are in good agreement with the experimental data. The paper also analyzes the impact of atmospheric turbulence on the communication in the system mainly for low-frequency (100Hz below) light intensity fluctuations. The system follow-up circuit plus AGC is proposed and the low-frequency sensitivity of the pyroelectric detector is reduced, which can basically overcome the atmospheric turbulence effect. In particular, the article emphasizes the use of 10.6μm band has a good fog haze ability, under clean atmospheric conditions comparable with visible, near infrared, but in adverse weather conditions is better than the above band. Due to the use of pyroelectric detectors, resulting in the system does not require harsh refrigeration technology, operation and maintenance is particularly convenient. For the coastal islands, rivers and lakes, border posts sentinel communications, has a special practical value. The system in 2km, 5km trial experiment, has access to the local network, voice clear, reliable work.