| 摘要 |
PROBLEM TO BE SOLVED: To provide an intercom system that adjusts an intercom to a suitable speech communication switching level according to the environment wherein the intercom is installed. SOLUTION: The intercom system enters a speech communication switching adjustment mode wherein suitable speech communication switching is performed without reference to an ambient noise level and an installation place state, and transmits a frequency spread signal whose audio band frequency is spread from a master unit CPU of a master unit to an automatic alternate speech communication circuit when entering the speech communication switching adjustment mode. The intercom system inputs a speech signal from a master unit microphone to the automatic alternate speech communication circuit, compares the frequency spread signal with the speech signal to transmits a state signal from the automatic alternate speech communication circuit to the master unit CPU, and varies through a fist electronic variable resistor the speech level input from the master unit microphone so as to vary a level of switching in response to the state signal. Then, the speech level from the master unit microphone which has been adjusted through the first electronic variable resistor is varied through a second electronic variable resistor to be equal to a speech level to a predetermined slave unit, thereby achieving suitable automatic alternate speech communication. COPYRIGHT: (C)2011,JPO&INPIT
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