| 摘要 |
PURPOSE: A multifamily video phone system is provided to modulate signals transmitted to a lobby phone and a video phone of each house, and to demodulate the received signals, then to switch input/output paths of the signals, thereby transceiving voice signals, video signals, and data through 2-line wiring. CONSTITUTION: A lobby phone(10) comprises as follows. A central processing unit(12) generates call data when a call button is inputted from a visitor, outputs a control signal, and switches a state of a relay(18) by controlling a relay driver(13). A buffer(11) temporarily stores input/output data. A pickup unit(16) photographs an image of the visitor. A modulator(15) modulates an image signal of the pickup unit(16), transmits the modulated image signal to a specific video phone(20), and modulates a voice signal of the visitor. A demodulator(14) demodulates a voice signal of a user transmitted through the video phone(20), and transmits the demodulated voice signal to the visitor through a handset(17). The video phone(20) is applied with the call data, and generates a calling sound.
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