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:


  • Single beam echosounder
  • Split beam echosounder
  • Dual beam echosounder
  • Multibeam sonar
  • Imaging sonar
  • Scanning sonar

Examples of phenomena

Vertical mount

Acoustic beam deadzone - referenced Acoustic beam deadzone    
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 electrical

System noise electrical
and intermittent acoustic noise

System noise possibly

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
Standard sphere calibration    
Submerged vegetation - reservoir bottom    
Structure, targets heading in different directions+    
Transducer ringing Not to be confused with the Near-field depth.  
Transducer tilted - diving fish+    


Transient noise
TVG-noise stripes    
Upward facing transducer Upward facing transducer    
Wideband ringing and side lobe return from a trawl body    

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
Using Echoview: Key concepts
Data processing workflow