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一、前言在国内,把超高频(12GHz 频带)卫星广播的实用化作为目标,1978年发射了实验用的广播卫星,现在正继续进行着各种实验。并制订了在1983年发射实用卫星的计划。由于从卫星发出的电波到达地面时变成微弱的信号,因而有必要研究低噪声接收设备,为此进行了专门的研究。图1是 NHK 研制的超高频接收机的方框图。从卫星发射来的超高频信号,在下变频器 UHF 带(实用卫星的场合为1GHz 频带)直接变换,最后经调频-调幅
I. Preface At home, we aimed to put the UHF (12GHz band) satellite broadcasting into practical use. In 1978, we launched experimental broadcasting satellites and now we are continuing with various experiments. And plans were made to launch a practical satellite in 1983. Since radio waves emitted from satellites become weak signals when they reach the ground, it is necessary to study low-noise receiving equipment, and special studies have been conducted for this purpose. Figure 1 is a block diagram of a UHF receiver developed by NHK. Ultra-high frequency signals transmitted from satellites are transformed directly in the downconverter UHF band (in the case of practical satellites, the 1 GHz band), and finally, frequency-modulated