Advertisement

Russian Journal of Nondestructive Testing

, Volume 55, Issue 8, pp 549–559 | Cite as

Using Pseudoorthogonal Signals to Reduce Noise Level in Ultrasound Testing of Highly Absorptive Materials

  • E. G. BazulinEmail author
  • V. K. Avagyan
ACOUSTIC METHODS
  • 13 Downloads

Abstract

To increase the signal-to-noise ratio when testing materials with a high level of absorption, it has been proposed to use complex signals, formed on the basis of code sets employed in Code Division Multiple Access (CDMA) technology, as probing signals. The code sequences in the code sets have a low level of cross-correlation function and a delta-like autocorrelation function. Echo signals are recorded by the double-scanning method, in which the elements of an antenna array sequentially emit unique probing signals phase-shift keyed according to the Kasami code, with the echo signals being recorded in each radiation cycle concurrently by all the elements in the antenna array. Since the shape of the “side lobes” of the compressed echo signals is different for each shot, reconstructing the image of reflectors using digital focusing of the antenna (DFA) reduces the level of the “side lobes”. As a result, when different code sequences of length 15 are used for each antenna-array element, this level may prove to be lower than when one sequence of length 63 is used for all the elements. Provided that a unique code set is used in each position, reconstructing the DFA image when scanning with an antenna array should further reduce the noise level and the level of the “side lobes”. The effectiveness of the proposed approach was demonstrated in a model experiment on reconstructing the image of side-drilled holes in a Plexiglas™ SO-1 calibration block, when using Kasami codes of lengths 15 and 63.

Keywords:

ultrasonic nondestructive testing double scanning triple scanning digital focusing with an antenna (DFA) maximum entropy method (MEM) C-SAFT whitening decorrelation Code Division Multiple Access (CDMA) 

Notes

REFERENCES

  1. 1.
    Advances in Phased Array Ultrasonic Technology Applications, Waltham, MA: Olympus NDT, 2007. http://www.olympus-ims.com/en/books/. Cited February 5, 2019.Google Scholar
  2. 2.
    Voronkov, V.A., Voronkov, I.V., Kozlov, V.N., Samokrutov, A.A., and Shevaldykin, V.G., On the applicability of antenna array technology in ultrasonic testing of hazardous production facilities, V Mire NK, 2011, no. 1 (51), pp. 64–70.Google Scholar
  3. 3.
    Bazulin, E.G., Vopilkin, A.Kh., and Tikhonov, D.S., Improving the reliability of ultrasonic testing. Part 1. Determination of the type of discontinuity in ultrasound testing with antenna arrays, Kontrol’ Diagn., 2015, no. 8, pp. 7–21.Google Scholar
  4. 4.
    Bazulin, E.G., Comparison of systems for ultrasonic nondestructive testing using antenna arrays or phased antenna arrays, Russ. J. Nondestr. Test., 2013, vol. 49, no. 7, pp. 404–423.CrossRefGoogle Scholar
  5. 5.
    Kovalev, A.V., Kozlov, V.N., Samokrutov, A.A., Shevaldykin, V.G., and Yakovlev, N.N., Pulse-echo method for testing concrete. Interference and spatial selection, Defektoskopiya, 1990, no. 2, pp. 29–41.Google Scholar
  6. 6.
    Bazulin, E.G., Utilization of double scanning in ultrasonic testing to improve the quality of the scatterer images, Acoust. Phys., 2001, vol. 47, no. 6, pp. 649–653.CrossRefGoogle Scholar
  7. 7.
    Chatillon, S., Fidahoussen, A., Iakovleva, E., and Calmon, P., Time of flight inverse matching reconstruction of ultrasonic array data exploiting forwards models, in NDT Natl. Conf., Canada, August 25–27, 2009.Google Scholar
  8. 8.
    Bolotina, I., Dennis, M., Mohr, F., Kröning, M., Reddy, K.M., and Zhantlessov, Y., 3D Ultrasonic imaging by cone scans and acoustic antennas, 18th World Conf. Nondestr. Test., Durban, South Africa, April 16–20, 2012.Google Scholar
  9. 9.
    Bazulin, E.G., Reconstruction of reflector images using the C-SAFT method with account for the anisotropy of the material of the test object, Russ. J. Nondestr. Test., 2015, vol. 51, no. 4, pp. 217–226.CrossRefGoogle Scholar
  10. 10.
    Varakin, L.E., Sistemy svyazi s shumopodobnymi signalami (Communication Systems with Noise-Like Signals), Moscow: Radio i Svyaz’, 1985.Google Scholar
  11. 11.
    Bazulin, E.G. and Kokolev, S.A., Increasing the signal-to-noise ratio in ultrasonic testing of repair welds using the technology of thinned antenna arrays, Russ. J. Nondestr. Test., 2013, vol. 49, no. 5, pp. 283–293.CrossRefGoogle Scholar
  12. 12.
    Kachanov, V.K., Application of orthogonal phase-shift keyed signals in ultrasonic flaw detection, Defektoskopiya, 1990, no. 9, pp. 39–46.Google Scholar
  13. 13.
    Kachanov, V.K., Kartashev, V.G., Sokolov, I.V., and Shalimov, E.V., Metody obrabotki signalov v ul’trazvukovoi defektoskopii / Uchebnoe posobie dlya studentov vuzov, obuchayushchikhsya po napravleniyam “Elektronika i mikroelektronika”, “Radiotekhnika” (Signal Processing Methods in Ultrasonic Flaw Detection / Textbook for University Students Enrolled in the Areas of “Electronics and Microelectronics”, “Radio Engineering”), Moscow: Moscow Power Eng. Inst., 2010.Google Scholar
  14. 14.
    Golay, M.J.E., Complementary series, IRE Trans., Inf. Th., 1961, vol. IT-7, no. 2, pp. 82–87.CrossRefGoogle Scholar
  15. 15.
    Kasami, T., Weight distribution formula for cyclic codes, Tech. Rep. no. R-285, Univ. of Illinois, April 1966.Google Scholar
  16. 16.
    Gold, R., Optimal binary sequences for spread spectrum multiplexing, IEEE Trans. Inf. Theory, October 1967, vol. 13 (4), pp. 619–621.  https://doi.org/10.1109/TIT.1967.1054048 CrossRefGoogle Scholar
  17. 17.
    de Bruijn, N.G., A combinatorial problem, Koninklijke Nederlandse Akademie v. Wetenschappen, 1946, vol. 49 pp. 758–764.Google Scholar
  18. 18.
    Chu, D.C., Polyphase codes with good periodic correlation properties, IEEE Trans. Inf. Theory, July 1972, pp. 531–532.  https://doi.org/10.1109/TIT.1972.1054840
  19. 19.
    Bazulin, A.E. and Bazulin, E.G., Deconvolution of complex echo signals by the maximum entropy method in ultrasonic nondestructive inspection, Acoust. Phys., 2009 vol. 55, no. 6, pp. 772–783.CrossRefGoogle Scholar
  20. 20.
    Zigangirov, K.Sh., Theory of Code Division Multiple Access Communication, New-York: IEEE Press, 2004.Google Scholar
  21. 21.
    Official website of EKHO+ company. http://www.echoplus.ru. Cited February 5, 2019.Google Scholar
  22. 22.
    Bazulin, E.G., The use of the inverse C-SAFT method for equalizing the spatial sensitivity of reflector images, Russ. J. Nondestr. Test., 2015, vol. 51, no. 2, pp. 108–119.CrossRefGoogle Scholar
  23. 23.
    Bazulin, E.G. and Vovk, A.S., Application of the maximum entropy method in ultrasonic flaw detection with allowance for the variable shape of echo signal, Nauchn. Tr. MEI, 2018, no. 5, pp. 111–119.Google Scholar

Copyright information

© Pleiades Publishing, Ltd. 2019

Authors and Affiliations

  1. 1.OOO NPTs Ekho+MoscowRussia
  2. 2.Moscow Power Engineering InstituteMoscowRussia

Personalised recommendations