Ocean Instruments SoundTrap ST640, Руководство пользователя

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Compatible hydrophones can be obtained from High Tech Inc USA with model code:
HTI-96-MIN/3V/Low Noise/SoundTrap/-165dB .
This model has bandwidth of 30 kHz. For higher frequency models we recommend discussing your
requirements with HTI.
Is is critical that unused channel connectors are protected with dummy wet plugs. Failure to do so
will result in damage.
3.4 Clock details
SoundTrap’s clock is synchronised to your PC whenever you click on the ‘deploy’ butto n, with an
accuracy of +/- 0.5s.
Internally the clock is maintained in UTC time. When files are offloaded to the PC file times are
converted to local time (using the PCs location settings) for population of the filenames. This means
that the dates and times in the filenames are always in the time zone of the PC that was used to
offload the files. This can be important where files are offloaded in a region other than that in which
they were recorded. Alternatively, filenames can be assigned UTC times by selecting the ‘Use UTC
time’ option under the tools menu.
Like most electronic devices, SoundTrap relies on a crystal oscillator for time keeping. The oscillator
used in the ST600 has an accuracy of +/- 5PPM, or +/- 0.44 seconds per day. The audio sample rate is
derived from the same oscillator, meaning the sample rate is subject to the same accuracy. The
oscillator will drift with temperature with this range. For more information on the clock accuracy
please see documentation for the oscillator - SiTime part SIT1552AC-JE-DCC-32.768D.
Sampling rate accuracy is also subject to occasional sampling gaps. The nature of SD flash memory
cards is such that occasional the memory card will fail to keep up with sampling, thereby resulting in
dropped samples. When this occurs, an entry will be written to the log (xml) files in the format
“sampling gap X us at sample Y”. There is an experimental option under the Tools menu ‘Zero Fill
Dropouts’. This function will attempt to fill any sampling gaps with a series of zeros. This may be
useful where more precise sampling timing is required.
3.5 Deployment hardware