S. R. More, V. H. Patankar, V. M. Joshi, K. R. Gopalakrishnan Electronics Division, BARC, Bombay 400 085
Keywords: Ultrasonic Imaging, Scan, SAFT, TOFD
ABSTRACT
An advanced Ultrasonic Imaging System has been developed for NDT/NDE of fabricated assembly parts, welded joints etc. The system is based around a personal computer IBM PC/AT 386 (or upwards) or compatible. All the major components of the system viz. Pulser/Receiver, Echo Data Acquisition Unit, Signal Processing-Conditioning Hardware have been configured in the form of PC-AT Add-on boards thereby converting the host PC into an Advanced Ultrasonic Imaging system. The Pulser provides a narrow spike (100 nsec. wide) with a 350 V peak amplitude @ variable P. R. F. The data can be acquired either with a single probe (Pulser/Echo mode) or using two probes (T/R or TOFD modes). The echo signals are amplified with a software selectable gain of 0- 40 dB in 0.25 dB steps. An 8 bit flash encoder digitizes the amplified unrectified (RF) echo signals with a software selectable sampling rate upto a maximum of 100 MSPS. On-line averaging of sampled echo streams permits enhancement of SNR. the system control software is fully menu driven and allows the operator to optimally select all the parameters of data acquisition for best utility of the system. A variety of signal processing routines such as SAFT, 1D filtering, 1DFFT etc. have been provided for processing & analysis of echo data. The B-Scan image (@ 512 x 512 x 8 bit resolution) is displayed on the SVGA monitor either in Pseudo colours or B/W with 64 gray shades. The display features also include
only an A-mode display with
Scroll facility and
On line cursors for distance/depth and amplitude measurements;
B mode display with a cursor and corresponding A-trace
C mode display
. A two axes stepper motor driven immersion scanning mechanism has also been developed for automated inspection.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 4, pages 2071 - 2074 Publisher:Ashgate Publishing Company
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