Page History

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