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312 IV型十二路载波电话设备 312 IV型载波电话设备系上海邮电器材厂产品,它包括ZM312IV型终端机、ZR312IV型增音机,是成套长途明线12路电话复用设备.这种设备用在一对架空铜线上可以增加12个优质双向通话电路,并可利用部分话路供传输调幅或调频电报、开放会议电话以及传输广播和传真电报之用.每一增音段平均距离为70～130公里,装设足够数量的增音机后,可使每转接段的直达通话距离延伸到1200公里.
312 IV-type 12-channel carrier telephone equipment 312 IV-type carrier telephone equipment is the Shanghai Posts and Telecommunications Equipment Factory products, which includes ZM312IV-type terminals, ZR312IV-type amplifiers, is a set of long-distance Ming line 12 telephone reuse equipment. Twelve high-quality two-way telephone circuits can be added to a pair of overhead copper lines and some of the telephone lines can be used for transmission of AM or FM telegraphy, open conference calls and transmission of broadcast and fax telegrams with an average distance of 70 ~ 130 km, after installing a sufficient number of amplifiers, the direct call distance per extension can be extended up to 1200 km.