| 摘要 |
Provided is a distance measurement system in which power consumption is minimized in an effective manner, the distance measurement system being suitable for applications such as a smart entry system in which a plurality of terminals are present. Distance measurement signal transmission/reception units (4a, 4b) transmit and receive, in a continuous manner, a radio signal for measuring the distance therebetween. A distance calculator (51) calculates the distance between the distance measurement signal transmission/reception units (4a, 4b) on the basis of the times at which the transmitted/received radio signal is transmitted/received. A representative setting unit (52) sets, as a representative, a portable terminal (1b) identified as having first entered a predetermined range by performing threshold value determination on the distance. In the terminal set as a representative, the process performed by the distance measurement signal transmission/reception unit (4b) is continued, and in a terminal that has not been set as a representative, the process performed by the distance measurement signal transmission/reception unit (4b) is stopped. |
