Echogram interpretation

The interpretation of echoes, represented by a progression of pings and samples, may not be easy. Transducer and electronic artifacts, can compete with signals from many types of biomass and the environment. The following images show examples of echogram interpretation:

Transducers

Examples of phenomena

Vertical mount

Acoustic beam deadzone - referenced Acoustic beam dead zone    
Attenuated signal Attenuated signal    
Bubbles from sediment+ Bubbles from sediment    
False bottom False bottom Simrad 120 kHz Ex60 data.

Intermittent noise
and false bottom

False bottom, renfree and Demer 2016. Simrad Ex 60 18, 38, 70, 120, and 200 kHz data

False bottom, Renfree and Demer 2016

 Fish aggregations, 2nd and 3rd echoes Fish aggregations, 2nd and 3rd echoes    
Impulse noise Impulse noise    
 Intensity steps+ Intensity steps    
Intermittent spike noise Intermittent spike noise    
 System noise+ System noise

 


 
 System noise electical

System noise electrical
and intermittent acoustic noise

System noise possibly
electrical

Side-lobe reflection from steep side of basin and tilted transducer mount+ Side-lobe reflection from steep side of basin and tilted transducer mount    

 

Signal from beam side lobes - referenced
   
Standard sphere calibration    
 Submerged vegetation - reservoir bottom     
Structure, targets heading in different directions+    
Transducer ring down, near field and far field working ranges    
Transducer tilted - diving fish+    

 

Transient noise
   
TVG-noise stripes    

Horizontal mount

Boat wake, fish and rock Boat wake, fish and rock
Imaging sonar - fish "arcing"
Multi-path reflections from fish when the beam is grazing the boundaries+
Wallowing fish+

+Screen shots of echograms displayed in BioSonics Visual Analyzer and the interpretations are included with the kind permission of Mr. James Dawson and Mr. Robert McClure of BioSonics.

See also

About echograms
About multibeam echograms