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.
a connection or a character string giving the name of the file to load.
sequence number of channel to extract, for multi-channel files.
sound speed, in m/s. If not provided, this is calculated
(35,15,30,eos="unesco"). (In theory,
it could be calculated using the temperature and salinity that are stored
in the data file, but these will just be nominal values, anyway.
character string indicating time zone to be assumed in the data.
a flag that turns on debugging. Set to 1 to get a moderate amount of debugging information, or to 2 to get more.
if provided, the action item to be stored in the log, typically only provided for internal calls.
An echosounder object.
Only the amplitude information (in counts) is determined. A future version of this function 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.
Various echosounder instruments provided by BioSonics are
described at the company website,
document listed as reference 1 below was provided to the author of this function in
November 2011, which suggests that the data format was not changed since
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.
The documentation for echosounder explains the
ctd objects, and also outlines the other functions
dealing with them.
Other things related to echosounder data: