| 摘要 |
PURPOSE:To sufficiently display the monitor function even in the case of trouble in plural positions by providing a means which decide an effective communication channel and discriminating it in each monitor station section whether the input signal from a current channel or a stand-by channel is used. CONSTITUTION:An information processing part 10 receives signals, which are received by a current up signal reception part 11' N and a stand-by up signal reception part 11' E, and checks validity of signals. A control signal 110a as the check result is sent to an up reception signal selecting part 13' to select normal one of a current up communication channel 7 and a stand-by up communication channel 9. The processing part 10 operates the selecting part 13' by its own decision to send the normal signal on the current up communication channel 7 or the stand-by up communication channel 9 to a host station through an up signal distributing part 14' and both of channels 7 and 9. Thus, it is substantiated that this signal is the effective signal by the local station.
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