| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve precision of a calculation distance by calculating a distance on the basis of a propagation delay time from transmission of a pulse signal to receiving in the case where an integration value in which a reflection pulse signal is obtained to be successively integrated at constant intervals exceeds a threshold value, and judging whether it is the reflection pulse signal by a judgement means in the case where it does not exceed the threshold value. SOLUTION: A control part 15 searches whether the integration value of a threshold value Vt2 or less for judging the existence and absence of a reflection body exists. At some time, it is judged whether the integration point of the threshold value Vt1 or more of a noise level exists. Because a reflection pulse signal or the fluctuation of the noise level is judged since at some time the integration point is between the threshold values Vt1 -Vt2 , pulse signal transmission is stopped once. It is judged whether the integration point of the threshold value Vt1 or more of the noise level exists. In the case where it does not exist, it is judged that a receiving pulse signal exists, and pulse signal transmission is started. A judgement part searches the four peak values of the output of the integration value, these are connected by straight lines to make intersection points the peak points, and a propagation delay time, i.e., a distance up to the reflection body is obtained.</p> |
