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Sentry Data Specifics

ABE and Sentry routinely carry instruments of acoustic and photographic surveillance. They excel at surveys of bathymetry, its chemical emissions and its magnetic properties. ABE is the current de facto vehicle for NDSF operations. Sentry will replace ABE once it is certified to do so (expected in 2008).

The standard AUV package of data that is delivered to the chief scientist will consist of these types and formats for all science dives:

  1. Navigation
    • the log files as assembled by DVLNav, described here
    • the collection of positions, based on transponder-based long baseline ranges that have been augmented with Doppler Velocity Log and post-processed in the following manner:
      • The vehicle's compass is recalibrated on the first dive in each new area
      • Using the navigational record of the first dive, transponder bottom positions are refixed by minimizing least squares error for fixes with three or more ranges
      • LBL ranges are filtered to recover good range measurements
      • The refined fixes, the recalibrated compass, and the Doppler navigator data are recombined using a Kalman smoother, yielding timestamped positions in decimal degrees
  2. Digital still photographs

    Timestamped images in JPEG format, 1024x1024 pixels x 12 bits/pixel

  3. Bathymetry
    • ABE, with a Simrad SM2000 sonar. Deliverables are bathymetric data in the following forms:
      • Raw data file (.smb format)
      • The above processed to an XYZ point cloud (ASCII, lat-lon-depth)
      • Bathymetry grid at 5 meter resolution (netcdf .grd)
      • Image of gridded bathymetry for working purposes only, not publication quality (.tif format)
    • Sentry, with a Reson Model 7125 sonar. Deliverables are bathymetric data in the following forms:
      • Raw data file (Reson format)
      • The above processed to an XYZ point cloud (ASCII, lat-lon-depth)
      • Bathymetry grid at 5 meter resolution (netcdf .grd)
      • Image of gridded bathymetry for working purposes only, not publication quality (.tif format)
  4. Multicolumnar timeseries of vehicle and science measurements
    • Comma-separated values, .csv format
    • Co-registered with data fields from guest science subsystems
      • time, longitude, latitude, depth, pressure, altitude, heading, conductivity, temperature, optical backscatter
  5. Additional vehicle parameters:
    • Magnetometer x, y, z components;
    • Engineering logs with pitch, roll, heading.

Last updated: March 28, 2008