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约在1947年,荷兰开始大规模地敷设了有12个星形四线组、导线直径为1.3毫米(40磅)的载波电缆.该电缆原来的传输频带为12～204千赫,可开通48个话路.当时所采用的方法及其依据,作者已在从前发表的文章中详细讨论过.为使本文更加完整,现将该文的要点在下面追述一下.当时要传输更高的频率似乎会因串音而带来麻烦.但是,能保证电缆在12～552千赫范围内传输120路的简单方法,在那时就已经有了发展.在这里要详细说明一下这种方法.
Around 1947, the Netherlands began large-scale laying of a 12-star four-wire carrier cable with a wire diameter of 1.3 millimeters (40 pounds). The original transmission band was 12 to 204 kHz and was switched on 48 The way the word was adopted at that time and its rationale was discussed in detail in a previously published article by the author.For the sake of completeness of this article, the main points of this article are recalled below. Can cause trouble due to crosstalk, but simple methods of ensuring that the cable can transmit 120 lines in the range of 12 to 552 kHz have been developed at that time, and a detailed explanation of this method is provided here.