Research on the Statistics of Grain Lattice Echoes and Their Use in Grain Size Estimation and Grain Echo Suppression.
Abstract
In NDE, a need exists for signal-to-noise ratio enhancement for noisy materials like centrifugally cast stainless steel, composite materials, some types of welded joints etc., because, the echoes of interest in the signal will be sometimes completely obsured by noise. Split spectrum processing is a signal processing technique for the signal-to-noise ratio enhancement in ultrasonic signals. The method utilizes the frequency dependent response of the interfering coherent noise produced by unresolvable scatterers in the resolution range cell. It is implemented by 'splitting' the frequency spectrum of the received signal by using Gaussian, overlapping bandpass filters and hence the name. Results of signal-to-noise ratio enhancement in signals obtained from real samples of centrifugally cast stainless steel, Carbon-Epoxy composite material and a 1020 steel welded joint are presented. The influence of various processing parameters on the performance of the processing technique is also discussed. An empirical algorithm, 'Polarity Thresholding', which provides an excellent signal-to-noise ratio enhancement when used in conjunction with 'Minimization' is also presented.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1986
- Accession Number
- ADA176996
Entities
People
- Robert C. Disque
- V. L. Newhouse
Organizations
- Drexel University