| 摘要 |
PROBLEM TO BE SOLVED: To provide a distance measurement system suitable for a smart entry system in which a plurality of terminals exist, and effectively restraining electric power consumption.SOLUTION: Distance measurement signal transmitting-receiving parts 4a and 4b continuously transmit-receive radio transmission for measuring a distance between both. A distance calculation part 51 calculates the distance between both based on the transmitted-received time of the transmitted-received radio transmission. A representative setting part 52 sets a portable terminal 1b determined as entering in the first inside a predetermined range as a representative by a threshold value determination to the distance. In the terminal set as the representative, processing of the distance measurement signal transmitting-receiving part 4b is continued, and in the terminal not set as the representative, the processing of the distance measurement signal transmitting-receiving part 4b is stopped. |
