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前言相干通信似乎正在进入商品化系统的研制阶段,其进展速度之快超过了人们一年前的预计。约在两年前,人们对商品化系统在90年代末期的目标曾持极为不同的看法,而现在,这种目标提前到了90年代中期,对此人们却无多大的争议。相干技术有希望大大提高接收机的灵敏度和选择性,由于这种吸引力,美国、英国、西德、丹麦以及日本这5个国家中,至少已有10个实验室正在研制利用其国产设备的相干通信系统。其中有3个研究集团似乎正致力于开发商品化产品:他们是位于Allentown,Pa的AT&T贝尔实验室的试制工厂、英国电信研究室的试制工厂和NTT公司的试制
Preface Coherent communications appears to be entering the stage of development of a commercial system that is progressing faster than people expected a year ago. About two years ago, people took a very different view of the commercialization system’s goal in the late 1990s, and now it is not until the mid-90s that there is much controversy over this goal. Due to the attractiveness of coherent technology, which greatly enhances receiver sensitivity and selectivity, at least 10 laboratories in the United States, the United Kingdom, the West Germany, Denmark and Japan have been developing their home-made equipment Coherent communication system. Three of the research groups appear to be working on the development of commoditized products: trial production at AT & T Bell Laboratories in Allentown, Pa, trial production at BT Research and trial production by NTT