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  • Diversion of Hydrophone and Seismometer data
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Seismometers

  • Initially sampled at 100 SPS (H..) and 1 SPS (L..)
  • During divert high rate channels dropped, maybe later returned
  • Currently sampled at 200 SPS (H..) and 8 SPS (M..)

Hydrophones

Hydrophone Listing

Hydrophone WAV audio file data product documentation

Arctic

Ocean Sonics icListen HF Hydrophone

  • No Navy intervention
  • FFT (Fast Fourier Transform) data sampled at 256 kHz
    • Sent continuously
  • wav data sampled at 64 kHz
    • We only get limited amount of wav files per day in "realtime"
    • All data will be recovered on next site visit

NEPTUNE

Naxys

  • Sampling at 96 kHz (002, 003 low gain problems)
  • Potential problems with dropped samples/timing
  • Changes in file size (53.33 s in the beginning, longer files mostly 5 minutes later on)
  • No divert
    • 5 minute files full bandwidth files without mode modifier
  • Divert
    • 5 minute files highpass filtered transition 6-6.5 kHz; mode HPF
    • Exception for VPS hydrophone at some point HPF transition 3-3.5 kHz; mode HPF
  • Return (after Navy assessment)
    • Historically: down-sampled to 12 kHz (12.000 SPS) file length 11 minutes 22 seconds (essentially 6 kHz lowpass data); no special mode that tells you that it's not original data
    • Currently should no longer be down-sampled

Ocean Sonics icListen HF Hydrophone

  • Sampling at 64 kHz
  • Filesize always 5 minutes
  • Future: 256 kHz FFT data that will not be diverted
  • No divert
    • 5 minute files full bandwidth files without mode 
  • Divert
    • in the beginning: 5 minute files highpass filtered transition 6-6.5 kHz; mode HPF
    • Currently: at some point HPF transition 3-3.5 kHz; mode HPF
  • Return (after Navy assessment)
    • in the beginning: Down sampled to 12.8 kHz (12.800 SPS) file length 5 minutes (essentially 6.4 kHz lowpass data); no special mode that tells you that it's not original data
    • Intermediate: Down sampled to 6.4 kHz (6.400 SPS) file length 5 minutes (essentially 3.2 kHz lowpass data); no special mode that tells you that it's not original data
    • Currently should no longer be down-sampled

Ocean Sonics icListen LF Hydrophone

  • Sampling at 4 kHz
  • Filesize  5 minutes except for returned data 10 minutes (to be fixed) 
  • No divert
    • 5 minute files full bandwidth files without mode 
  • Divert
    • Currently: no realtime data
    • Issue: WHY can we not have filtered data during divert (LPF filter requires a lot of computational power...)
  • Return (after Navy assessment)
    • Historical: Full data 10 minutes; no special mode that tells you that it's not original data
    • Currently: Full data 5 minutes

VENUS

IOS

  • Array with 3 elements not synchronized until recently: Sampling at 44.15, 120.12, 50 kHz in succession, 50 kHz seems to be optimum
  • Filesize  highly variable, currently 5 minutes
  • Return
    • Historical: No data returned/recorded during divert
    • Currently: high-pass filtered data returned

Ocean Sonics icListen HF Hydrophone

Ocean Sonics icListen LF Hydrophone

  • Sampling at 4 kHz
  • Filesize  5 minutes 
  • No divert
    • Full data; no mode
  • Divert
    • Sample rate changed to 250Hz on hydrophone, then Lowpass filtered 3-4Hz transition; mode LPF
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