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大家知道,收音机接收信号强弱的变化是客观存在的矛盾,而这些矛盾产生的原因是多种多样的。例如,广播电台发射功率大小的不同,距离的远近,接收地点环境、气候的变化以及由于短波信道中存在的衰落现象等等,都会使到达收音机输入端的信号电平具有很大的起伏。根据实际测量,一般慢衰落的深度可达14dB 左右,而快衰落的深度可达30dB。若收音机的增益是不可调整的,那么,接收弱信号
As we all know, changes in the strength of radio reception signals are objective contradictions, and the causes of these contradictions are manifold. For example, the difference in the size of the transmitted power of radio stations, the distance, the reception site environment, the climate change, and the fading present in short-wave channels all contribute to the large fluctuations in the level of the signal arriving at the radio input. According to the actual measurement, the depth of general slow fading can reach about 14dB, and the depth of fast fading can reach 30dB. If the radio’s gain is not adjustable, then the weak signal is received