The two transpolar shortwave time signal circuits,Moscow and Irkutsk to the Great Wall Station in Antarctica, are used to study the fading characters for shortwave long circuit.

为了研究过极区长电路落特性，在南极长城站收测莫斯科、依尔茨克授时台信号，并给出各频率对应落、落率、落平均持续时间等参数统计特征和落幅分布曲线。