Digital scientific echosounder

Digital scientific echosounder is a type of scientific echosounder used in hydroacoustic research. In a digital scientific echosounder system, the returned acoustic signal is digitized for improved performance.

Collected acoustic data is "stamped" with geographic information for precise positional information (coordinates and time). This enables analysis and incorporation of the results into a Geographic Information System (GIS) for further analysis, correlation with other variables, mapping, and display.

Currently, the only three manufacturers of scientific-quality digital echsounders commonly used for resource assessment are BioSonics, HTI (Hydroacoustic Technology, Inc.) and Simrad.

Features of modern digital scientific echosounder technology include:

• Low side-lobe transducers
• Simple data collection
• Low system noise
• Wide dynamic range
• High system stability
• High accuracy
• Easy system expansion
• Multiplexing systems (multiple transducers can operate simultaneously on the same system)

Scientific software for analysis of hydroacoustic data

Specially written software is available for analysis of hydroacoustic data for assessment of underwater physical and biological characteristics. "Fish" here can apply to any "target" in the water column, e.g., fish, plankton, squid, mammal. All results can be imported into a GIS for additional analysis, correlation with other variables, mapping, and display.

Bathymetry 

the depth (range) of the bottom of the river, lake, or ocean below the transducer.

Range 

the distance between the transducer and the "target". This is determined by precise timing from sound generation to sound reception (by the transducer).

Bottom type; Seabed type; Substrate type; or Sediment type 

can be assessed and classified (e.g., sand, rock, soft mud, hard mud).

Fish quantity 

can be estimated and reported as numbers of fish or biomass.

Fish size 

can be determined in a relative manner, based on acoustic "target size".

Fish behavior 

can be assessed through a combination of instantaneous and temporal measures and observations. Spatial distribution, size distributions, diurnal activity, predator-prey relationships, migration rates, temporal activity, etc. can be observed and quantified.

Submersed aquatic vegetation; Submerged aquatic vegetation; or SAV 

can be detected and assessed for location, density, and height.

Fish passage 

can be quantified for fish movement past a fixed-location hydroacoustic monitoring system. Examples include: Migrating salmon or fish entrained by water intakes.