ANALYSIS OF YARN UNEVENNESS BY USING A DIGITAL-SIGNAL-PROCESSING TECHNIQUE

This paper describes a microcomputer system using digital-signal proce ssing for yarn-unevenness analysis. The system converts the analogue s ignal from an Uster Tester into digital form and then analyzes the sig nal by using digital-signal-processing techniques. The yarn unevenness is described by four statistical parameters (statistical average, pro bability-density function, correlation functions, and power-spectral-d ensity function) as usually adopted for a steady stochastic process. T he probability-density function, known to be closely correlated with f abric-appearance quality, is derived in detail, and a new scheme for n umerical approximation of a shorter-term signal from a longer-term one is proposed. The system can be used to expand the use of the Uster Te ster, providing insight for the analysis of yarn unevenness.