| 摘要 |
PURPOSE:To raise the safety, and also, to increase a processing speed by detecting a passing position of a projectile from a time difference for reaching plural impulse wave detecting means provided on the same plane. CONSTITUTION:Plural pieces, for instance, for pieces of impulse wave detecting means 1 are installed on the same plane. When a projectile passes through the inside or the outside of the target surface, each impulse wave detecting means 1 detects its impulse wave. Each time difference of the time when each impulse wave detecting means 1 has detected the impulse wave is measured by a time difference measuring means 2. An arithmetic processing part 3 determines a passing position of the projectile from the time difference which has been measured by this time difference measuring means 2.
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