| 摘要 |
PROBLEM TO BE SOLVED: To dispense with exchange of alarms and change-over signals between both indoor and outdoor units, to reduce a cable, to simplify arrangement work, to reduce cost and to facilitate maintenance by individually issuing alarm in each units, when a fault occurs and executing change-over into a reserve machine. SOLUTION: When a fault occurs in the modulating parts 3a and 3b of a transmission side indoor unit IDU, a fault detecting signal is generated, alarm is issued, a change-over control signal is generated, a change-over switch SW 4 is controlled and change-over is executed into the reserve machine. When a fault occurs in the transmission modulating parts 7a and 7b and/or the transmission high frequency parts 8a and 8b of the outdoor unit ODU, alarm is issued similarly, SW 9 is controlled and change-over is executed into a reserve machine side. In the meantime, when the fault occurs in the demodulating parts 18a, 18b of IDU at a reception side and the reception modulating parts 14a, 14b and the reception high frequency parts 13a and 13b of ODU, alarm is respectively issued similarly and change-over is made into the reserve machine side by controlling signal distributors (HYB) 17 and 12.
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