| 摘要 |
PROBLEM TO BE SOLVED: To optimally remove an interference, and accurately estimate a position even if there are a plurality of ultrasonic ranging apparatuses in an environment. SOLUTION: In a method for ultrasonic measurement, a plurality of ultrasonic waves spectrum-spread with different codes are received by a plurality of receivers so as to generate respective received signals. Signals having amplitudes of each threshold value or more are extracted from the received signals by using a plurality of the threshold values. After interference signals are generated so as to be different per threshold value and spread with ultrasonic codes other than desired ultrasonic code, the interference signals are removed from the received signals, the received signal from which the interference signals are removed are generated per threshold value and despread with the desired ultrasonic code. The maximum correlation value between despread received signals is obtained per threshold value. The threshold value for acquiring the maximum correlation value obtained per threshold value is determined. A travel distance of the desired ultrasonic wave is calculated from an arrival time when the received signal corresponding to the determined threshold value reaches the receiver. COPYRIGHT: (C)2009,JPO&INPIT
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