short transients and so give poorer detection of delphinids) or an intermediate value which will tend
to reduce sensitivity to both short and long transients but not by much.
Blanking time:
Time that must then elapse after a detection before another detection can be made.
Useful to avoid detecting echoes from a click or to prevent detecting a large number of clicks if an
animal is buzzing near the recorder.
Store Snippets:
Select to enable storage of detection snippets.
Snippet pre- and post-trigger durations
: The time with respect to the detection at which the snippet
will be taken. The snippet starts
pre-trigger
seconds before the detection and ends
post-trigger
seconds after the detection. These are both limited to 1.5 ms maximum which is more than long
enough to cover odontocete clicks. The number of samples saved per snippet is determined by the
sum of the pre- and post-trigger times. With the maximum settings, 1728 samples will be saved per
snippet.
4.1.4
Output File formats
The ST click detector produces two additional output files per recording with suffixes 'bcl' and 'dwv'.
These are in addition to the .wav and .xml files generated normally. The Pamguard interface
automatically interprets these files when displaying detection and continuous recording results. For
users interested in accessing the data using other interfaces, the details of the file formats are given
below:
•
xml
This is the metadata file produced by SoundTrap to document each recording. The
ST detector adds metadata about the detector and the user settings to this file.
•
wav
This is a Microsoft WAV format file containing the decimated continuous sound
recording produced in parallel with the detector. The sampling rate is selected by the user
but would typically be 48kHz or 96kHz to maximize recording time. By default, sound data is
compressed in the SoundTrap using the lossless X3 compressor but this is transparent to the
user: the .wav file contains the reconstituted uncompressed data.
•
dwv
This is a Microsoft WAV format file containing the wideband sound snippets for each
detection. The sampling rate is 576 kHz and the snippets are arranged contiguously with a
constant number of samples per snippet. The size of each snippet is set the by the pre- and
post-trigger user parameters. The snippet size in samples will be close to
round((pre+post)*576e3) but the precise sample count can be found in the .xml file (see the
Matlab tools for an example of how to extract this information automatically). By default,
