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一、引言全国范围内的地下矿区所采用的音频(AF)呼叫式电话和低频(LF)铁道流动运输车通信系统已有二十年之久了。我们高兴地看到,在这期间由于新技术、新设备高效发展,系统已发生了很大变化。从长远的观点出发,我们采用了大量
I. INTRODUCTION The audio (AF) calling phones and the low frequency (LF) rail mobile communications systems used in underground mines nationwide have been in existence for two decades. We are pleased to see that there has been a great change in the system during this period due to the efficient development of new technologies and new equipment. From a long-term point of view, we use a lot