| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress the attenuation of voice signals at a simultaneous broadcast targeting a plurality of dwelling units. <P>SOLUTION: A dwelling unit 2 includes a second voice transmission circuit 26b having higher impedance than input and output impedance of a lobby intercom 1 or a management room intercom 3. At the simultaneous broadcast, a trunk line L1 is connected to a simultaneous broadcast route including the second voice transmission circuit 26b. Thus, the attenuation of the voice signals can be suppressed even when a plurality of dwelling units 2 are connected, because the input impedance on the dwelling unit 2 side is higher than the input and output impedance of the lobby intercom 1 or the management room intercom 3. <P>COPYRIGHT: (C)2012,JPO&INPIT |
