| 摘要 |
PCT No. PCT/JP80/00188 Sec. 371 Date Jan. 7, 1982 Sec. 102(e) Date Jan. 7, 1982 PCT Filed Aug. 20, 1980 PCT Pub. No. WO82/00727 PCT Pub. Date Mar. 4, 1982.An ultrasonic surveillance system which emits pulse-like ultrasonic waves to an area under surveillance, which statistically compares a reflected-wave pattern established by receiving ultrasonic waves reflected from the under surveillance with a predetermined reference pattern, and which produces an alarm signal when these two patterns are not in agreement. According to this system, the alarm signal is prevented from being erroneously produced by ultrasonic noises. |
