bluezone group
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Sonar for Sewer Inspection
High frequency (2.25 MHz) short range sonars provide the answer for imaging and profiling sewer pipelines where visual methods (CCTV) cannot be used. With multi-frequency sonars, operators can generate highly detailed full-scale images with just one unit. Sonars can provide both internal pipe profiling within pipes of various sizes and imaging of areas of interest in the pipe.  Sonars are typically deployed on small robots such as crawlers, ROVs, and/or on flotation platforms which can be propelled or move with the flow.

The primary purpose of the imaging sonar is as a viewing tool that is used in place of CCTV when turbidity prevents obtaining a visual image.
For sonar imaging a fan-shaped sonar beam scans a given area. The beam's movement through the water generates points that form a sonar image of the given area. The different coloured points, representing the time (or slant range) of each echo return, plot a line on a video display screen. These visual images provide the viewer with enough data to draw conclusions about the environment being scanned. The operator will be able to recognize sizes, shapes and surface reflecting characteristics of the chosen target. 

The primary purpose of the profiling sonar is as a quantitative measuring tool.
The profiling process is the selection of the echo returns for plotting. The sonar selects the echo returns, typically one or two returns for each "shot", based on a given criterion for the echo return strength and the minimum profiling range. The information gathered from the selection criteria forms a data set containing the range and bearing information. The profile data is useful for making pen plots of bottom profiles, trench profiles, internal and external pipeline profiles.

 Profiling Sonar used to build a 3-dimensional view 
of a pipeline.
  Imaging sonar showing horseshoe pipe.
 The Pipe Profiling Sonar mounted at the forward end
of the sewer pontoon provides a full field of view.
 The sonar display is easily provided on a ruggedised 
laptop PC. 
 Profiling sonar data post-processed and point clouds 
extracted to create pipeline profile.