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312IV型载波机是上海邮电器材一厂产品之一,它是由ZM312IV型终端机和ZR312IV型增音机组成的成套的通信设备.在线径3.0～4.0毫米、线距20厘米的一对架空铜线上,装置312IV型载波机后,可以增加十二个双向电话通路.此外,还可以同时在这一线对上装置202型三路载波电话机,使再增加三个双向电话通路.连同原来的一个音频电路,共计可获得十六个电话通路,因此每个电话通路的平均建设费用就大大地节省了.如果每隔70～130公里装置一个ZR312IV型增音机,则两个终端机间的最大通信距离
312IV carrier is one of the products of Shanghai No.1 Posts and Telecommunications Equipment Factory, which is a set of communications equipment composed of ZM312IV type terminal and ZR312IV type of repeater .A pair of overhead copper with diameter of 3.0-4.0mm and wire spacing of 20cm In addition, up to twelve two-way telephone lines can be added to the line after the addition of a Type 312IV carrier, and an additional two two-way telephone lines can be added to this pair at the same time. An audio circuit, for a total of sixteen telephone channels, provides a significant savings in the average construction cost per telephone channel. If a ZR312IV repeater is installed every 70 to 130 kilometers, The maximum communication distance