produced on the trace from the transducer on the opposite side of the fish 

 from the wall (this is also referred to as cross talk) . 



32. Circular-shaped vertical features such as steel sheet pile cells 

 can result in image artifacts called diffraction hyperbolae. Often, cavities 

 and cracks can be recognized as dark traces perpendicular to the otherwise 

 unbroken dark/light linear boundary resulting from the wall face. Cavities of 

 rectangular shape may cause points of high reflectance due to the "corner 

 reflector" phenomenon, i.e., returns are reflected directly at the transducer 

 over a range of incident angles. Refer to Morang (1987)* for a more detailed 

 discussion and examples of these phenomena. 



* Morang, A. W. 1987. "Side-Scan Sonar Investigation of Breakwaters at 

 Calumet and Burns Harbors on Southern Lake Michigan," Miscellaneous 

 Paper CERC-87-20, US Army Engineer Waterways Experiment Station, Vicksburg, 

 MS. 



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