read.echosounder: Read an Echosounder File

Description

Reads a biosonics echosounder file. This function was written for and tested with single-beam, dual-beam, and split-beam Biosonics files of type V3, and may not work properly with other file formats.

Usage

read.echosounder(file, channel = 1, soundSpeed = swSoundSpeed(35, 10, 50), tz = getOption("oceTz"), debug = getOption("oceDebug"), processingLog)

Arguments

file

a connection or a character string giving the name of the file to load.

channel

sequence number of channel to extract, for multi-channel files.

soundSpeed

sound speed, in m/s. (The documents on Biosonics instruments suggest that this could be inferred from values in the file header, but test files proved this to be false.)

character string indicating time zone to be assumed in the data.

debug

a flag that turns on debugging. Set to 1 to get a moderate amount of debugging information, or to 2 to get more.

processingLog

if provided, the action item to be stored in the log, typically only provided for internal calls.

Value

An object of class "echosounder" with standard slots metadata, data and processingLog that are described in the documentation for the object echosounder-class.

Bugs

Only the amplitude information (in counts) is determined. A future version of this funciton may provide conversion to dB, etc. The handling of dual-beam and split-beam files is limited. In the dual-beam cse, only the wide beam signal is processed (I think ... it could be the narrow beam, actually, given the confusing endian tricks being played). In the split-beam case, only amplitude is read, with the x-axis and y-axis angle data being ignored.

References

Various echousounder instruments provided by BioSonics are described at the company website, http://www.biosonicsinc.com/. The document listed as [1] below was provided to the author of this function in November 2011, which suggests that the data format was not changed since July 2010.

[1] Biosonics, 2010. DT4 Data File Format Specification. BioSonics Advanced Digital Hydroacoustics. July, 2010. SOFTWARE AND ENGINEERING LIBRARY REPORT BS&E-2004-07-0009-2.0.