| 摘要 |
PURPOSE:To enable detection of deficiency of equipment which generates a deficiency sound only instantaneously by continuously determining an average within a fixed time of the frequency spectrum from an object to be inspected so as to compare a frequency spectrum with the current average spectrum. CONSTITUTION:A noise of a motor 1 is taken into a frequency analyzer 10 through a microphone 2 and an amplifier 3 and a frequency spectrum A corresponding to the noise is determined continuously to be applied to a differential device 11 and an averager 20 with which an average within a fixed time in terms of frequencies is determined based on the spectrum A and the average spectrum B is applied to the differential device 11 as comparison input. The spectrums A and B are compared with an arithmetic mechanism to determine a deviation value. In other words, after a comparison with the differential device 11, deviation value are totalized with a totalizer 14 through an absolute value circuit 13 and the total sum G applied to a discriminator 15. The discriminator 15 compares the total sum G with the set value and judges the object to be good when the total sum G is below the set value while to be defective when it exceeds the specified value. |
