| 摘要 |
PROBLEM TO BE SOLVED: To provide a collective housing intercom system that can detect a visitor without installing a sensor such as a human sensor at the common entrance of a collective housing, and further notifies the visitor of visitor video information during being absent and the like if the visitor is a resident who has just come back.SOLUTION: A resident carries around a mobile terminal 5 for performing communication using a 60-GHz band, and a collective entrance device 1 is provided with a 60-GHz band radio communication unit 1b for communicating with the mobile terminal 5. The 60-GHz band radio communication unit 1b includes: a transmission unit 15 for transmitting a radio wave to the mobile terminal 5; a reception unit 16 for receiving a radio wave; a transmission/reception control unit 17 for controlling transmission and reception; and an approximation determination unit 20 for determining the presence or absence of a visitor. The transmission/reception control unit 17 turns off data communication baseband units 18, 19 in a standby state to repeatedly transmit a carrier radio wave not modulated in the 60-GHz band at prescribed intervals, detects the phase of a reflection wave of the carrier radio wave received by the reception unit 16, and determines that there appears a person at a common entrance on detecting the reversal of the phase.SELECTED DRAWING: Figure 2 |
