Hydrophone Data Acquisition and Diversion Mode

For hydrophone data products only (audio and spectrogram data):

Hydrophones that have both low and high frequency sensors will have the data acquisition mode option while the other hydrophones will have the data diverion mode option.

Diversion Mode

For security reasons, the military occasionally diverts seismic and acoustic data. Often the divert consists of splitting the data into a low and high pass filtered components with the file names appended with "-LPF" or "-HPF", respectively. Sometimes one-half of this diverted is available live, while the other component is withheld for review. Usually that withheld data is returned, after a delay of 3 days to 2 months. Withheld data is usually altered by band-pass filtering, often with decimation or resampling. In rare circumstances, withheld data is returned whole or only the missing LPF/HPF data is returned (this data is not labelled "-LPF" or "-HPF", but it should be). This returned data is not usually compatible with original/non-diverted data. Data diversion is further explained in the data diversion page.

Original Data

This option will cause the search to return results for original data only. Files labelled with "-HPF" or "-LPF" are excluded as well as any files that overlap in time with "-HPF" or "-LPF" files. For spectral probability density plots and spectrograms, 'Data Diversion Mode: Original Data' will appear in the plot title.

This is the default option.

Low Pass Filtered

This option will cause the search to return results for diverted data that has been low pass filtered only (only files with "-LPF" in the their file-names). For spectral probability density plots and spectrograms, 'Data Diversion Mode: Low Pass Filtered' will appear in the plot title.

High Pass Filtered

This option will cause the search to return results for diverted data that has been high pass filtered only (only files with "-HPF" in the their file-names). For spectral probability density plots and spectrograms, 'Data Diversion Mode: High Pass Filtered' will appear in the plot title.

All

This option will cause the search to return results for all data. For spectral probability density plots and spectrograms, 'Data Diversion Mode: High Pass Filtered' will appear in the plot title. This is only way to see data that overlaps in time with files labelled "-LPF" or "-HPF".

File-name mode field

"-LPF" or "-HPF" is added to the file-name when the quality option is set to high or low pass filtered data, i.e. ICLISTENHF1234_20110101T000000Z-HPF.wav. For spectral probability density data products, 'All' may be added to the file-name, as these plots can join LPF, Original and HPF data together into one plot if the spectral frequency bins are the same (data with different frequency content will make addition plots with labels indicating the frequency range). For brevity, 'Original' does not get added to the file-name.

Acquisition Mode

For hydrophones with both low and high frequency sensors. The low sampling frequency has a frequency of most likely 16 Khz and the high sampling frequency has a frequency greater or equal to then 128 Khz.

Low Sampling Frequency

This option will cause the search to return results for the low sample frequency data only (only files with the frequency -16Khz in their file-names). For spectral probability density plots and spectrograms, 'Data Acquisition Mode: -16 Khz ' will appear in the plot title.

High Sampling Frequency

This option will cause the search to return results for the high sample frequency data only (only files with the frequency -128Khz in their file-names). For spectral probability density plots and spectrograms, 'Data Acquisition Mode: 128 Khz' will appear in the plot title.

All

This option will cause the search to return results for both the low sampling frequency and high sampling frequency. For spectral probability density plots and spectrograms, the low and high frequency data will be plotted separately.