LINE INTERRUPT MONITOR
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专利名称：LINE INTERRUPT MONITOR
发明人：FUDA HITOSHI,KOBAYASHI EIICHI,TORII SHINJI
申请号：JP4321190
申请日：19900223
公开号：JPH03247025A
公开日：
19911105
专利内容由知识产权出版社提供
摘要：PURPOSE:To monitor line interrupt stably by superimposing a pilot signal onto a main signal at a sender side and suppressing the component of the pilot signal at a receiver by calculation. CONSTITUTION:A pilot signal (b) is superimposed on a main signal (a) and sent by a sender side coupling circuit 3 and a receiver side monitors a level change in the pilot signal (b) to discriminate the presence of line interruption. Then a signal whose level and frequency are equal to the pilot signal (b) superimposed on the main signal (a) and whose phase differs therefrom by 180 deg. is obtained and an adder circuit 6 is used to add the obtained signal to the pilot signal (b) or a signal whose level, frequency and phase are equal is subtracted from the pilot signal (b) to obtain a signal (e) not including the pilot signal (b) in the received output signal. Thus, the line interruption is monitored stably without giving effect onto the transmission of the substantial main signal.
申请人：NEC CORP,NEC ENG LTD
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