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简述猫头鹰(Owl)卫星电视摄象机系统和采用二次电子电导管(SEC)的几种独特的设计特点。分析信噪比对扫描速度的依赖关系,对于一个应用低噪声场效应管的放大器,信噪比可以做到最大限度。最佳扫描速度对应于一个8KHz带宽的放大器和一个超过250MΩ阻值的栅极偏置电阻。为了满足最佳扫描速率和低数据遥测带宽的需要,采用一间歇的扫描方法,用这种方法扫描,扫描电子束仅在一部分扫描时间达到靶的非扫描区域。这个扫描方法综合了低噪声电平和在单扫中高效擦除电荷的优点。单曝光扫描有降低电视系统效率的缺点,只要在光敏面上提供一小的偏置照明,就可避免由于扫描电子束的速度分布而引起的低效率。
A brief account of the owl satellite television camera system and several unique design features using a secondary electron tube (SEC). Analyzing the dependence of signal-to-noise ratio on scan speed, the signal-to-noise ratio can be maximized for an amplifier using a low-noise FET. The best scanning speed corresponds to an 8KHz bandwidth amplifier and a gate bias resistance of more than 250MΩ. In order to meet the need of optimal scanning rate and low data telemetry bandwidth, an intermittent scanning method is adopted. In this method, the scanning electron beam reaches the non-scanning area of the target only during a part of the scanning time. This scanning method combines the advantages of low noise level and efficient erase charge in single sweep. Single-exposure scanning has the disadvantage of reducing the efficiency of the television system by avoiding the inefficiencies caused by the velocity distribution of the scanned electron beam as long as a small bias illumination is provided on the photosensitive surface.