Concept Validation and Detectability Limitations for Direct-Sequence Spread-Spectrum Ultrasonic Evaluation System
Direct-Sequence Spread-Spectrum Ultrasonic Evaluation (DSSSUE) technology has now taken a practical shape . Two independent prototype instruments have been designed with different approaches, a hardware and a software implementation. The instruments record the aggregate acoustic state of the test object and the associated measurement system in the form of “ultrasonic correlation signature” [1,2]. These correlation signatures are compared with the signatures obtained at a later point in time (or from an identical object) to detect if the test object has undergone any change in its geometry, composition and homogeneity etc. The DSSSUE instruments have been undergoing concept validation and detectability verification for the ultrasonic testing of both large structures and small piece parts. This paper reports on the results of these tests, the detectability limitations that apply to practical scenarios are described, including limitations due to processing time, sampling granularity, and transducer placement. Various tradeoffs associated with implementation of the DSSSUE technique are addressed.