| 摘要 |
PURPOSE:To select an installation place when radio wave interference can be evaded by previously selecting the installation place by providing a lamp which indicates the radio wave interference. CONSTITUTION:In the receiving circuit 120 of a slave equipment, a detecting circuit 126 supplies a signal CDET indicating whether or not there is an intermediate frequency signal Si to a CPU 140. When it is judged from the signal CDET that there is a carrier, the CPU 140 performs a terminating process on condition that its ID is detected. When its ID is not detected, the disturbing wave presence lamp 133 illuminates and a 4-second timer starts counting. When the carrier presence state exceeds four seconds, it is judged that a down control channel can not be used. Further, when there is not carrier or when a carrier continues within four seconds even if it is present, the master equipment is called from the slave equipment. When there is no answer from the master equipment, it is judged that there is the disturbing radio wave on an up control channel. Then the disturbing radio wave presence lamp 133 continues to illuminate.
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