oce (version 0.9-18)

echosounder-class: 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, intimeSlow,longitudeSlowandlatitudeSlow. These are used in plotting maps withplot.echosounder.
• An interpolated record of the instrument position, intime,longitude, andlatitude. 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 thesoundSpeedargument toread.echosounder, so altering the value of the latter will alter the echosounder plots provided byplot.echosounder.
• The echosounder signal amplitudea, a matrix whose number of rows matches the length oftime, etc., and number of columns equal to the length ofdepth. Thus, for example,a[100,]represents the depth-dependent amplitude at the time of the 100th ping.
• A matrix namedbexists for dual-beam and split-beam cases. For dual-beam data, this is the wide-beam data, whereasais the narrow-beam data. For split-beam data, this is the x-angle data.
• A matrix namedcexists for split-beam data, containing the y-angle data.
• In addition to these matrices, ad-hoc calculated matrices namedSvandTSmay 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.

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.