Raw variables derived from Navico Group Lowrance (sonar log) data files

This page describes the variables that Echoview can derive from Navico Lowrance data files.

*.slg data
*.sl2 data
*.sl3 data
Using raw variables from Navico Group Lowrance (sonar log) data files

Data processing
Calibration settings
Fileset date and time
Downscan, Sidescan and Sidescan left/right raw variables
Track course raw variables

See also

*.slg data

Derived raw variable may include:

heading data
position GPS fixes
line data sounder detected bottom
unspecified dB single beam pings Primary
unspecified dB single beam pings Secondary

*.sl2 data

Derived raw variable may include:

heading data
track course data (channel n)
position GPS fixes
line data sounder detected bottom
unspecified dB single beam pings Primary
unspecified dB single beam pings Secondary
unspecified dB single beam pings Downscan
unspecified dB single beam pings Sidescan (channel n)
unspecified dB single beam pings Sidescan left (channel n)
unspecified dB single beam pings Sidescan right (channel n)

*.sl3 data

Derived raw variable may include:

heading data
track course data (channel n)
position GPS fixes
line data sounder detected bottom
unspecified dB single beam pings Primary
unspecified dB single beam pings Secondary
unspecified dB single beam pings Downscan
unspecified dB single beam pings Sidescan (channel n)
unspecified dB single beam pings Sidescan left (channel n)
unspecified dB single beam pings Sidescan right (channel n)

n is an integer for the channel ID.

Using raw variables from Navico Group Lowrance (sonar log) data files

Data processing

Many operators in Echoview do not process the unspecified dB format raw variables read from Lowrance data files.

Use the Type conversion operator to convert from unspecified dB to another format. For example, to TS before single target detection or target tracking.

Note that Bottom classification and vegetation analysis features are not available for Lowrance data.

Read the Downscan and sidescan raw variables section below before undertaking data processing with these raw variables.

Calibration settings

The sample values for the raw variables read from Lowrance data files may exceed the threshold for Echoview's operators.

Use the CalibrationOffsetUnspecifieddB and PulseDuration (e.g., 0.1 ms) calibration settings to adjust the sample values for use with Echoview's operators.

Fileset date and time

Lowrance data files do not record a start date and timestamp for the fileset. Specify the start date and timestamp using the Fileset Properties dialog box.

Downscan, Sidescan and Sidescan left/right raw variables

If available, Echoview reads Downscan and Sidescan raw variables from the data file, and dervies Sidescan left/right raw variables from the latter. However, these are mainly for visualization or experimentation only.

In particular, Sidescan raw variables extend from negative to positive ranges, making them incompatible with many of Echoview's operators.

In deriving the Sidescan left and Sidescan right variables, Echoview assumes that the two sides are symmetric and centered at 0 m in range. Echoview inverts the sample range and depth for Sidescan left variables so that they are positive.

Track course raw variables

This is heading data.