| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve a distance resolution without increasing memory and detect an intruder positively by comparing a row of compression data of a row of data detected by an ultrasonic wave and its partial row of data and then a row of compression data when no intruder exists in a monitoring space and its partial row of data. SOLUTION: An ultrasonic wave transmission part 4a transmits an ultrasonic wave S4 at each specific time, an ultrasonic wave reception part 4b receives an ultrasonic wave S5, and a writing part 8 compresses a row of data and writes detection compression data into a detection compression data storage part 7b. In that case, when an intruder exists in a monitoring space, a distance between an ultrasonic sensor and an object for reflecting the ultrasonic wave S4 becomes shorter. A comparison part 9 reads a row of background compression data that is stored in a background compression data storage part 7a with a row of detection compression data stored in a detection compression data storage part 7b and compares both successively from data being stored at the start of the memory. The comparison part 9 judges that there is an intruding object in the monitoring space if both differ.</p> |
