About interval and layer values in export files
Exports of cell analyses, including analysis by cells and analysis by regions by cells, typically contain Interval and Layer variables. You must specify grid settings in the Show time/distance grid and Show depth/range/Line-referenced grid sections on the Grid page of the Variable Properties dialog box. The numbering system that is used to identify intervals ad layers in the export file depends on the time/distance and depth/range units that were used to define the grid.
Note: Preview the interval and layer cell coordinates on an echogram using the Ctrl+L shortcut key.
Interval numbering
The Interval variable in an export is the span between vertical grid lines.
Select any of the following from the Show time/distance grid section of the Grid page of the Variable Properties dialog box. The start interval number 0 or 1 may vary with interval type. Use Start interval numbering from the first ping in the echogram to assign the first Interval a value of 1.
|
Grid type |
Description of Interval |
|
None |
Export not available. |
|
Time (minutes/hours/days) |
The first Interval is the time of the first ping represented as the number of spans from 1970-01-01 00:00 (see Unix time). Specify the span for these, and between each subsequent Interval in Time between grid lines (minutes/hours/days). |
|
GPS distance (nmi/m) |
The first Interval corresponds to the first GPS fix. Specify the span between each subsequent Interval in Distance between grid lines (nmi/m). |
|
Vessel log distance (nmi) |
The first Interval corresponds to the first vessel log distance. Specify the span between each subsequent Interval in Distance between grid lines (nmi). |
|
Ping number |
The first Interval is 1. Specify the span between each subsequent Interval in Number of pings between grid lines. |
|
Water current distance (m) |
The first Interval corresponds to the first water current distance (see About speed data). Specify the span between each subsequent Interval in Distance between grid lines (m). |
Layer numbering
Layer numbering is determined by:
-
the units selected in the Show depth/range grid list on Grid page of the Variable Properties dialog box, and
-
whether depth mode or range mode is selected in the Echogram mode list on the Echogram page of the EV File Properties dialog box.
Notes:
- The same layer in an echogram can be numbered differently if you change between depth and range mode.
- Pre-Echoview 5, the SimradDraftLogging may have affected layers and export results.
- Additional layer-related information is available for export in the form of optional analysis variables in the Analysis Domain group on the Export page of the EV File Properties dialog box.
|
Depth/range/Line-referenced units |
Echogram mode |
Numbering system in export file |
|
Surface (depth of zero) |
Depth |
Measured from Surface (depth of zero), nominally the water surface. The first layer (from the water surface to the first grid line) is layer 1. Where data exists above the water surface the first layer above the water surface is layer 0 and subsequent layers are numbered negatively (-1, -2, -3 ...). |
|
Transducer face (range of zero) |
Range |
Measured from Transducer face (range of zero). The first layer (from the transducer face to the first grid line) is layer 1. Layer numbers below the transducer are positive, layer numbers above the transducer are negative. |
|
Line-reference |
Depth or Range |
Measured from a selected line in the EV file. The first layer above the Line-reference is layer 0. Layers above the first layer are negative. Layers below the Line-reference are positive. |
See also
About depth, range and altitude
About exporting analyses
Exporting integrations