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前面两讲,我们分析了卫星电视广播系统的基本原理及卫星电视接收机的性能,得出了很多对设计接收机极为有用的公式。本讲就运用以上知识对接收机的技术参数进行计算。并对接收机的总体方案进行分析。一、变频次数及中频选择接收机的干扰主要是邻近频道干扰、镜象干扰及中频干扰。采用二次变频对抑制邻近频道干扰及镜象干扰有利,但电路复杂,故多用
In the previous two talks, we analyzed the basic principles of satellite television broadcasting systems and the performance of satellite television receivers and found many formulas that are extremely useful for designing receivers. This lecture on the use of the above knowledge of the receiver’s technical parameters are calculated. And analyze the overall scheme of the receiver. First, the number of frequency conversion and IF receiver interference is mainly adjacent channel interference, image interference and IF interference. The use of secondary frequency conversion to suppress adjacent channel interference and image interference is beneficial, but the circuit is complex, so the use of