echosounder-class {oce} | R Documentation

## Class to store echosounder data

### Description

Class to store echosounder data, with standard slots `metadata`, `data` and `processingLog`. The `data` slot is a list containing

- An infrequently updated record of the intrument position, in `timeSlow`, `longitudeSlow` and `latitudeSlow`. These are used in plotting maps with `plot.echosounder`.

- An interpolated record of the instrument position, in `time`, `longitude`, and `latitude`. Linear interpolation is used to infer the longitude and latitude from the variables listed above.

- `depth`, vector of depths of echo samples (measured positive downwards in the water column). This is calculated from the inter-sample time interval and the sound speed provided as the `soundSpeed` argument to `read.echosounder`, so altering the value of the latter will alter the echosounder plots provided by `plot.echosounder`.

- The echosounder signal amplitude `a`, a matrix whose number of rows matches the length of `time`, etc., and number of columns equal to the length of `depth`. Thus, for example, `a[100,]` represents the depth-dependent amplitude at the time of the 100th ping.

- A matrix named `b` exists for dual-beam and split-beam cases. For dual-beam data, this is the wide-beam data, whereas `a` is the narrow-beam data. For split-beam data, this is the x-angle data.

- A matrix named `c` exists for split-beam data, containing the y-angle data.

- In addition to these matrices, ad-hoc calculated matrices named `Sv` and `TS` may be accessed as explained in the next section.

### Methods

Accessing values. Data may be accessed as e.g. `echosounder[["time"]]`, `echosounder[["depth"]]`, `echosounder[["a"]]`, etc. Items in `metadata` must be specifield by full name, but those in `data` may be abbreviated, so long as the abbreviation is unique. In addition to the actual data, some derived fields are also available: `echosounder[["distance"]]` calls `geodDist` to compute calculate distance along the ship track, `echosounder[["Sv"]]` returns a matrix of backscatter strength in DB, and `echosounder[["TS"]]` returns a matrix of target strength in dB.

Assigning values. Everything that may be accessed may also be assigned, e.g. `echosounder[["time"]] <- 3600 + echosounder[["time"]]` adds an hour to time.

Overview of contents. The `show` method (e.g. `show(echosounder)`) displays information about the object.

### Author(s)

Dan Kelley

### See Also

A file containing echosounder data may be read with `read.echosounder`, and a echosounder object can also be created with `as.echosounder`.

Statistical summaries are provided by `summary.echosounder`, while `show` displays an overview. The `findBottom` function infers the ocean bottom from tracing the strongest reflector from ping to ping.

Echosounder objects may be plotted with `plot.echosounder`.

The contents of `echosounder` objects may be altered with `subset.echosounder`, or with the the `[[]]` scheme discussed in the previous section; skilled users may also manipulate the contents directly, but this is not recommended because it is brittle to changes in the data structure.

[Package oce version 0.9-18 Index]