| 摘要 |
<p>PROBLEM TO BE SOLVED: To determine the presence/absence of radio interference from responsiveness of a radio part.SOLUTION: In an intercom system, a habitable room unit 2 includes: a habitable room unit radio interference detection part 21 for detecting the presence/absence of radio wave radiation from external peripheral equipment before starting radio communication to a handy terminal 4; a habitable room unit radio transmission part 22 for transmitting a test signal to the handy terminal 4 by means of a radio signal on a predetermined channel when the radio wave radiation is not detected by the habitable room unit radio interference detection part 21 and, on the other hand, transmits the test signal on a predetermined channel that does not influence the radio wave radiation, in timing delayed from the timing of transmitting the test signal to the handy terminal 4 by a predetermined back-off time when the radio wave radiation is detected; a habitable room unit radio receiving part 23 for receiving the test signal from the handy terminal 4; and a time measuring part 24 which is started in the timing when the detecting operation is performed for the first time by the habitable room unit radio interference detection part 21, and measures a loop-back time until the habitable room unit receiving part 23 receives the test signal.</p> |
