The report concerns seeing into rock by means of sonar. Because sound waves are coupled into rock by means of a fluid to avoid the transducer detecting transverse sound waves, and this fluid has a velocity lower than that of rock salt, the salt causes the original sonar beam to diverge. The result is that a large mass of rock is insonified leading to multiple signals which are difficult to interpret. A successful method is described to overcome this problem by producing a narrow beam in salt to determine the azimuth and elevation of the various targets seen in time. It involves the use of a high frequency transducer driven to two frequencies that causes the SALT itself to go nonlinear and generate the difference frequency which is comparable to that of the high frequency beam. It is believed that this breakthrough could drastically improve the ability of the sonar probing system to discriminate reflected signals in salt in azimuth and elevation. Unsuccessful experiments on attentuation measurements of sound in salt are described, as well as successful tests, to improve the signal to noise ratio of the signals reflected from discontinuities in the salt. Measurements on the amount of noise in salt as a function of frequency are briefly discussed.

  • Corporate Authors:

    Texas A&M University, College Station

    College of Geosciences
    College Station, TX  United States  77843

    National Science Foundation

    Engineeing and Applied Science, 1800 G Street, NW
    Washington, DC  United States  20550
  • Authors:
    • Unterberger, R R
  • Publication Date: 1979-9-30

Media Info

  • Pagination: 95 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00317951
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: NSF/RA-790255 Prog Rpt.
  • Contract Numbers: NSF-APR76-21764
  • Files: TRIS
  • Created Date: Jul 22 1980 12:00AM