EM710 backscatter Processing - Normalizing the Outer Beams Traces

This research used EM710 multibeam data in the EDBS65 mode. The narrow beams (1 degree) and reduced swath (130 degrees) produce outer beams recovering only ~7% of the total swath width. But, systems capable of emitting more than one crosstrack profile per transmission started to be developed, which will allow surveyors to extend their swath again (150 degrees) without loosing alongtrack superposition. Despite the lower quality of outer beams (>65 degrees) to bathymetric purposes due to the refraction problem, the capacity of logging them can be useful for seafloor classification applications. Therefore, normalization of outer beams still represent a good solution for newer sonars. The figures below show the trace patterns for the entire swath and for the first beam:

Backscatter Intensities of the Entire Swath

Backscatter Intensities of the Beam 0

Following, some images from backscatter processing are presented. Visually, the improvements seem to be irrelevant because backscatter correction of ~6dB (12 DN_value) is blurred in the gray-level scale used to represent the data. But, this normalization still is important to increase the quality of algorithms used for seafloor classification.

Raw Backscatter
Beam Pattern Normilized
Outer Beams
Trace Pattern Normalized

Last updated January 26, 2007 by Aluizio at omg.unb.ca