1 / 15

Adapting Passive Ideas

Adapting Passive Ideas. Passive Case:. From our Sonar. Target Strength describes the fraction of energy reflecting back from the target. Reverberation Noise. Reflections from non-target objects is greater that noise. Reverberation limited. Reverberation. Volume Reverberation. Surface

camilla-shaffer
Télécharger la présentation

Adapting Passive Ideas

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Adapting Passive Ideas Passive Case: From our Sonar Target Strength describes the fraction of energy reflecting back from the target

  2. Reverberation Noise Reflections from non-target objects is greater that noise. Reverberation limited

  3. Reverberation

  4. Volume Reverberation Surface Reverberation Sources of Reverberation Backscatter • Fish and smaller biological marine organisms • Entrapped air bubbles • Microthermal structure • Velocity microstructure • Variations in the characteristic impedance of the medium (e.g. dust and dirt) • Surface – air-water interface • Ocean bottom

  5. Solid Angle r r Since dA Similarly Solid Angle Units are Steradians There are 4p steradians in all directions

  6. Developing a Volume Reverberation Equation – Beam forming and Traveling to the Target Spherical Spreading

  7. Developing a Volume Reverberation Equation – Scattering Strength Scattering Strength – fraction of energy backscattered

  8. How thick is the Volume? c

  9. Developing a Volume Reverberation Equation – Scattering Strength c

  10. Developing a Volume Reverberation Equation – Traveling Back to Receiver c

  11. Developing a Volume Reverberation Equation – Receiver Beam Pattern c

  12. Reverberation Level - Volume

  13. Take a deep breath Volume Scattering Strength (dB) Equivalent two way beam width – Equivalent solid angle of the sending and receiving array

  14. Volume Scattering Strength Diurnal Migration Shrimp-like euphausids, squid and copepods Fish (gas filled swim bladder) – freq differences Higher frequencies – zoo plankton, phytoplankton fed on by small pelagic fish (siphonphones and cephlopods) Collectively called the DSL (Deep scattering layer)

  15. Equivalent two way beam width

More Related