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

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

Examples of phenomena

Vertical mount

Acoustic beam deadzone - referenced
Attenuated signal
Bubbles from sediment+
False bottom		Intermittent noise and false bottom	False bottom, Renfree and Demer 2016
Fish aggregations, 2nd and 3rd echoes
Impulse noise
Intensity steps+
Intermittent spike noise
System noise+
System noise electrical		System noise electrical and intermittent acoustic noise	System noise possibly electrical
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
Wideband ringing and side lobe return from a trawl body

Horizontal mount

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