| 摘要 |
Interlaced or twisted yarn is passed between an optical transmitter and receiver to produce an original signal which varies in response to the changes in dimension of the yarn. Such original signal is compared using cross-correlation with an expected signal as produced by an ideally processed yarn to produce a processed signal indicating by its value the degree of matching of the original signal with the expected signal. The amplitude of the processed signal is noted relative to a predetermined threshold value representing an acceptably processed yarn. The expected signal is devised by performing a frequency analysis on the original signal to establish a peak frequency which is used to determine the distance between nodes in an ideally processed yarn.
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