Title: SENDAS: AN APPROACH MODULAR DIGITAL SIGNAL PROCESSING FOR AUTOMATED NDE

Abstract:
Automated Non Destructive Evaluation (ANDE) by ultrasound requires high quality acoustic images obtained at high scanning speeds. Although Digital Signal Processing (DSP) would help to increase image quality by improving signal to noise ratio, dynamic range, lateral and axial resolution, feature enhancement, etc., the time spent by computations, has prevented the extensive use of many well known algorithms in the hard real time environment of ANDE.

This paper describes a different approach, based on modular DSP, which constitutes one of the key concepts of the SENDAS' architecture. In SENDAS, algorithms are mostly implemented at the hardware level by Processing Modules (PMs), making extensive use of high density programmable logic and specific digital signal processors. Each PM is specialized on a given task or algorithm. Several PMs can be chained in a pipeline and all of them operate concurrently at high speed (currently at 10 MS/s, independently of the algorithm performed).. All PMs adhere to an electrical and mechanical standard so tbet many configurations are possible. This allows system evolution by incorporating both, new methods and technology advances in PMs, while keeping invariant the overall support and concept of the architecture. The high level of integration achieved allows up to six PMs to be fitted on a single PC board.

The SENDAS concept includes both, analog and digital signal processing. A final step of data reduction, provides a small set of qualified data to the evaluation computer. This allows complex processing at high scanning speed {more than 8000, 1024 points A-scans every second). Currently developed processing modules include digital and spatial filtering, EMI noise cancellation, deconvolution, split spectrum processing, multigated multi-peak detectors, envelope extraction, data reduction, etc. as well as linear and logarithmic amplification (covering 100 dB of dynamic range), multi-DA C generators, programmable pulsers and channel multiplexing.

Some relevant results using the SENDAS concept are presented in this work, which shows an increase of orders of magnitude in processing speed of the proposed approach over the conventional software based methods.

Keywords: Non Destructive Evaluation, Real-time digital signal processing, deconvolution, digital filtering, acoustic image enhancement, computer architecture.

1) SENDAS: stands for the Spanish: Sistema pare Evaluacion No Destructive de Arquitectura Segmentada.

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]