| 摘要 |
PURPOSE:To activate together all devices in each room, by providing a general calling device near front gate devices, detecting an emergency alarm signal transmitted from a device in a room and operating all modulators for the front gate devices. CONSTITUTION:Video, sound and control signals from a front gate device 1c are modulated at a modulator 6c and demodulated at a demodulator 8c at a room device 4c via a distributor 2 and a branching device 3, transmitted to the room device 4c, and a transmission signal from the room device 4c is informed to the front gate device 1c through the reverse path. Since the frequency is different depending on ducts 5a-5d, the simulataneous calling between each gate device and rood device is attained. If an emergency alarm signal is transmitted from the room device 4c, the signal is modulated by a modulator 9c, transmitted to a general calling device 10 in a carrier frequency (f), demodulated and modulated again at the modulators 6a-6d and informed simultaneously to the room devices 4a-4d. |
