Localization at the Lime Kiln acoustic observatory

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In 2009, a new hydrophone array was deployed in Lime Kiln State Park. Here we describe the array and track our efforts to localize sounds within it.

The array consists of two experimental nodes: a northern one with hydrophones mounted on cement-filled tires and spaced ~8m apart; and a more rigid southern one also with 4 hydrophones, but located ~400m along-shore. The north node also hosts a Reson hydrophone that is calibrated and has a flat response over the full range of frequencies in killer whale calls, whistles, and clicks.

Photo gallery | Admin tasks and field notes (Google spreadsheet)


  • July 19, 2009: deployed hydrophones 3 and 4 of the north array
  • July 20, 2009: secured new intertidal cable protectors
  • July 25, 2009: deployed hydrophones 2 and 1 of north array (blog post)
  • August 09, 2009: deployed 4 hydrophones on south array structure (slack ~13:30-14:00)
  • August 12, 2009: localization experiments with Chuck Greene, Adam Frankel, and bioacoustics course

Locations (WGS84)

Coordinates in lat/lon and UTM

Array geometry worksheet (Google spreadsheet)

  • North Array located (actually our estimate of element #4) ~ N 48.51571, W 123.15294 Remember: hydrophone 4 is closest to shore; 1 is furthest out at end of 4-element array (see July 25, 2009 blog post for depths and bearing between hydrophones)
  • South Array located ~ N 48.51306, W 123.15011
  • Lime Kiln light house ~ N 48.51578, W 123.15261
  • Distance between N and S array is ~ 360.8 meters at a bearing of ~ 144.7 degrees

Lime Kiln coastline

  • [GPX file downloaded from Val's Garmin III]
  • [Coastline track lat lon table from GPX file]
  • [Coastline waypoints lat lon table from GPX file]

Localization and calibration

Lime Kiln bathymetry

The blue line represents the average bathymetric profile off-shore of the Lime Kiln lighthouse. The red trace is the bottom from a single pass with downward looking 200kHz Biosonics echosounder. Bob Otis says that orcas typically are 100-300m offshore when they pass the lighthouse. LK-bathy.png