Title: REMOTE SENSING AND PROCESSING IN AUTOMATED NON DESTRUCTIVE EVALUATION

Abstract:
Automated Non Destructive Evaluation by ultrasound is frequently carried out by means of a scanning robot which is remotely located from the evaluation site. Usually signals are sent in analog form, perhaps after passing through a head amplifier. Multichannel systems require several long shielded cables to reach the computer, where they are digitized and processed. Apart from the cable count, this has the shortcoming of noise sensitivity, which can degrade the dynamic range and signal integrity.

To overcome this drawback, this paper presents a new approach, where signal acquisition and processing is done locally near the transducer by a multichannel remote system, and usually only a reduced set of digital data is sent to the evaluation computer. Signal processing is supported by a pipeline architecture where a wide variety of complex algorithms are performed in real time by dedicated digital processors at a sustained rate of 10 Msamples/s. This results in reduced data sets containing all the relevant information for the evaluation task, which are transmitted to the central computer through a full duplex, 5 Mb/s, point to point serial communication line. Several remote stations can be served from a single central computer.

This approach has several advantages. First, the simplicity of wiring, specially when arrays of transducers are employed in the inspection process. Second, it provides a quite high noise immunity with low installation costs (a single coaxial cable). On the other hand, complex computations can be performed in real time, and most controlling operations of the NDE equipment are decentralized from the evaluation computer which only takes care of robot movement and synchronism. As a result, an increase of the scanning speed and an improvement of image quality are obtained. Results show the performance of arrangements for different applications.

Source: Proceedings of the 'NDE applied to Process Control of Composite Fabrication' - Conference, 1-2 Oct 1996 St. Louis, Missouri. Publisher and Organizer: Nondestructive Testing Information Analysis Center (NTIAC) Texas Research Institute Austin, Inc. Austin, Texas [http://www.ntiac.com] [Buying the Proceedings]